Testing Metals? Don’t Over Strain Yourself!

When testing metals, the rate at which the specimen is being strained can affect important material properties, and thus affect important results such as offset yield and even tensile strength. Major metals testing standards such as ISO 6892 or ASTM E8 specify certain strain rates at which tests should be run. Pull a metal specimen at a constant rate throughout the test…sounds easy enough right?

In fact, achieving a constant strain rate can be difficult due to system compliance. As a continuously yielding specimen is being pulled in tension, the entire load string (frame, grips, load cell, adapters, etc.) are also deforming due to the typically high load seen in metals testing. Once the specimen yields the stiffness of the load string changes again and since the load plateaus, the deformation of the load string also plateaus. Once this occurs, all of the movement of the frame crosshead is translated into specimen elongation.

It is important for a testing machine to compensate for the changing stiffness seen in the load string throughout a test. If you are interested in learning more about strain control and how it can affect your testing results, please leave a comment below. 

Also, please stay tuned to for a video showing a strain control test in accordance to ISO 6892! Read more

Why Automatic Extensometry?

When testing the mechanical properties of a specimen, being able to accurately and repeatedly measure the strain the specimen sees is crucial. Many testing standards require that a separate device, commonly known as an Extensometer, be used to ensure the most accurate strain data possible.

So before you run a test, attach a device onto the specimen to measure the strain… that doesn't sound bad, now does it? Now think about having to test hundreds of specimens. Odds are, manually attaching an extensometer to every specimen will add significant time to your testing process. This is where an automatic extensometer should be used.

Automatic extensometers allow the user to simply place their specimen into the grips that are being used during the test and hit “start”. You don’t have to worry about attaching the extensometer and removing it once the test is done; it’s done for you! Automatic extensometers can save time, increase repeatability, and reduce operator influence on results.  If you are interested in automatic extensometry, check out the AutoX 750. Read more

What is R-Value?

R-value (also known as “Plastic Strain Ratio”) is a measurement of the drawability of a sheet metal. Simply put, it measures the resistance of a material to thinning or thickening when put tension or compression. R-value is a very important material property to understand for materials that will be formed into various shapes in their end use. When testing in accordance to popular standards such as ISO 10113 or ASTM E517, R-value is required.

There are two methods to calculate R-value, a manual version and an automatic version. We can assume that the volume of the specimen during the test remains constant to make the calculations easier (see below for details). The manual version of calculating R-value requires that the user measure the initial and final width and length of the specimen using calipers. The automatic method requires the user to measure the axial strain (as opposed to the strain along the thickness of the specimen) and transverse strain to calculate R-value.

The best range over which to calculate R-value is after yield point elongation and before ultimate tensile strength. The benefit of using the automatic method of measuring R-value is that the specimen can be pulled until failure, thus allowing the user to calculate properties such as ultimate tensile strength or strain at break. However, in the manual method, you are to pull the specimen beyond yield-point elongation, but the strain should not exceed the strain at ultimate tensile strength. Once you pull the specimen to this point, you are to unload the specimen to take the final measurements with your caliper. 

The equation to calculate R-value is shown below:

Since it is difficult to measure the thickness of the material as it is plastically deforming, we can assume that the volume of the specimen remains constant and thus:

To learn even more about R-value, check out ASTM E517 or ISO 10113.

Have any questions about plastic strain ratio? Leave a comment below and I'll respond to you soon~

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Plastics for Life

The interface between engineering and medicine has been expanding in recent decades - universities are now offering dedicated bio-engineering degrees. One particular application of modern engineering in medicine is the use of polymers as implants in order to aid in the healing process or replace damaged tissue.

Cranial Implants
Head injuries can be life-changing in a way that few other injuries can. Treatment can involve implantation of a skulls prosthesis, which is quite understandably a very delicate procedure requiring the utmost care and attention. However, it is also critical to select appropriate materials, for purposes of production and bio-compatibility. This is where plastics are proving to be extremely useful. In a recent research project, a team of dedicated professionals has created a process for manufacturing bespoke cranial implants with precision, speed and at minimal cost. The patient is taken for an MRI scan and the results are converted by a computer into a 3D model. Using a 3D production method like laser sintering, the implant is then generated. The whole process could take out a great deal of time and complexity involved in the surgical procedure.

Tracheal implants
Similar bio-technology is being used in throat repair. The Trachea is a long tube that connects the lungs to the mouth. When it becomes damaged, it can be very difficult to repair, and implanted materials can cause problems for the patient’s immune system. But using a 3D printed scaffold seeded with the patient’s own stem cells, an implant can be devised that is 100% compatible with the patient’s body. This technology is very transferable into many structures in the body, as the basic manufacturing technique is very flexible and the patient’s own cells are integrated into the implant. The bio-compatibility of the polymer structure ensures that the body integrates the implant, rather than rejecting it
.
However, implantation of any foreign device is a risky procedure, and the doctors and engineers responsible need to be 100% certain of success before engaging in a procedure. Implants should be thoroughly tested on a quality basis in order to prevent deployment of deficient products.

With a combination of Tensile, Compressive, Fatigue and Impact machines (among many others), we have a slew of solutions for a variety of bio-mechanical tests. In particular, we have a well-established history in stent testing and experience with a number of other bio-medical applications. We also have a unique environmental control unit for testing at 37 degrees.

Why not contact us to find out about the testing capabilities that we can offer? Read more

Happy Holidays

To share a little holiday cheer, I've worked with some of our blog authors (aka application specialists) to put together a fun montage of testing various types of holiday materials from wrapping paper to ornaments to garland ....

Enjoy and happy holidays!

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Bluehill Updates

Parasar Kodati, our Bluehill^® Product Manager, wrote an exciting post on our Bluehill blog about new updates to the software, as well as announces a new product that makes managing and analyzing results so much easier.

Check it out~ Read more

Question from a Customer

Q. What is the difference between percentage of full-scale and percentage of reading?

A. The accuracy of a device describes how close a measurement is to the actual value. It is usually presented in one of two forms: percentage of full-scale or percentage of reading.

Percentage of full-scale, usually shown as %FS, is a fixed error, and therefore, has a greater influence at lower measurement values. For example, if a load cell has a 200 lbf capacity and an accuracy of 0.3%FS, the error is 0.6 lbf throughout the measurement range. Therefore, at a measurement of 20 lbf, the 0.6 lbf error is 3% of the reading. This is outside of the ASTM E4 requirement that measurements should be within 1% of reading.

Percentage of reading is usually shown as %RO. For example, if a load cell has a 200 lbf capacity and an accuracy of 1% RO, then at a measurement of 20 lbf the error is 0.2 lbf or 1% of the reading, and within ASTM E4 requirements. Devices that specify accuracy as a percentage of reading typically have a wider range of use, since this is a more difficult specification to meet. Read more

Balancing the Load Cell

We are often asked how frequently an operator should balance the load cell during testing. Many lab managers require the operator to balance a load cell before the start of a new sample; others require balancing the load cell before testing every specimen. We believe that either procedure is acceptable, as long as you follow one major rule:

 

Never balance the load cell when there is a specimen clamped in both grips

Instron load cells can detect a change in load as a result of simply gripping the specimen. If the load is balanced after a specimen is gripped, you risk zeroing out a real load. This real load will be subtracted from or added to reported results, thereby falsely increasing or decreasing actual values depending on whether or not there was a compressive or tensile load on the specimen before the load cell was balanced.

If you notice a change on the load channel display after gripping, you can remove the load using automated software features such as preload or specimen protect, or by manually adjust the position of the crosshead. Read more

Measurement Uncertainty in Calibration

Instron’s reputation depends upon the quality of its products, the accuracy of its measuring devices, such as load cells and extensometers, and its services to regularly verify that those devices are performing to a required standard. For many years, the tag line “The Difference is Measurable” has shown our commitment to this accuracy. But how do we show it in practice?

A measurement offers a quantitative value to a property of an item. How heavy is it? How long is it? How hot is it?

No measurement can be said to be completely accurate. There is always some degree of doubt about the result of a measurement. For example, there may be some degree of inaccuracy in the measuring device itself or there may be differences in how people perform or read a measurement. That doubt is called the uncertainty of the measurement.

Good practices, such as regular maintenance and traceable calibrations, careful calculations, regular training, and accurate and consistent record keeping all help to maintain system performance and increase measurement accuracy. However, to properly judge the quality of any measurement, we need to quantify and report the uncertainty associated with that measurement.

We need to know two things: the width, or interval, of the margin of uncertainty, and how confident we are that the true value is within that margin. For example, we might say that the gauge length of a specimen measures 25 mm, having an uncertainty of measurement of 0.11 mm with a 95% confidence level. This

means that we are 95% sure that the gauge length is between 24.89 mm and 25.11 mm. The uncertainty statement is an indication of the quality of the measurement.

In short, any measurement result is only complete when a statement of the uncertainty in the measurement accompanies it. When the uncertainty in a measurement is evaluated and stated, you can properly evaluate the quality of the measurement.

Instron’s calibration standards and processes in North America and Asia are accredited by the National Voluntary Laboratory Accreditation Program (NVLAP). NVLAP is a program administered by the National Institute of Standards and Technology (NIST), the National Metrology Institute (NMI) of the United States. NVLAP regularly assesses Instron’s competence in performing accurate calibration and verification processes including the accuracy of the equipment used in those processes.

There are many different accreditation organizations worldwide, and several in the USA. To ensure that the different accreditation organizations harmonize their standards and processes so that they can accept each other's accreditations internationally, the International Laboratory Accreditation Cooperative (ILAC) was established and has now more than 70 accreditation bodies worldwide as signatories to their Mutual Recognition Arrangement (ILAC-MRA).

In 2010, ILAC published the ILAC Policy for Uncertainty in Calibration to harmonize the expression of uncertainty of measurement on calibration certificates and on scopes of accreditation of calibration laboratories. One of the major requirements of this policy is that each calibration verification
measurement should be accompanied by the associated uncertainty measurement.

Take a look at your last calibration certificate. If you have a certificate issued from another calibration laboratory, you may see only a general statement relating to uncertainty of measurement. However, if the Instron Calibration Laboratory has issued your certificate, you will see that each individual result is accompanied by an uncertainty measurement that has been calculated with that result.

Instron has long considered the reporting of uncertainty of measurement to be good metrological practice and has been reporting measurement uncertainties that are consistent with the new ILAC requirements for many years. Instron’s commitment to offering quality products and services shows in many ways. The accurate reporting of measurement uncertainty with every calibration result is one more reason why we say:
The Difference is Measurable. Read more

Grip Penetration Effects

How To Determine Effective Gauge Length

If gripping pressure on the clamped specimen is not uniform throughout the clamped area, a certain amount of specimen extension may take place within the grips. When this happens, if the elongation is measured from the test curve and a calculation of precentage elongation is based on the separation between the grip at the start of the test, the resulting figure will be in error.

Extension of the specimen within the grips is referred to as "grip penetration". It may not be apparent from examining the load elongation curve whether grip penetration has occurred since it will not produce a stick-slip effect, but it is proportional to the applied load. As grip penetration is proportional to load, the load elongation curve will remain smooth and apparently normal.

A method for determininng the presence and magnitude of possible grip penetration is to plot elongation against gauge length for a given force (Fx). If the resulting line, when extrapolated to zero gauge length, does not pass through the origin, but gives a positive displacement on the elongation axis, then this is the restult of grip penetration. It is essential when performing these tests to always test the specimen at the same strain-rate since certain materials are strain-rate sensitive. For example, the longer the gauge length, the faster the required crosshead speed, and the ratio between the gauge length and the crosshead speed will be constant.

Calculating Effective Gauge Length

The intercept gives a value (Ej) representing elongation within the grip at a specified load. The quantity AE represents the true elongation for a corresponding gauge length or grip separation. When calculating elongation from a load versus strain graph, the value Ej should be subtracted from the total elongation before dividing this value by the gauge length or grip separation figure. Read more

Looking After Your Grips

Any successful gripping solution can be adversely affected by poor maintenance. Many common gripping techniques rely on friction or local surface deformation of the specimen to function. If the gripping surfaces become worn or contaminated, a loss in gripping efficiency occurs. Ultimately, this causes the specimen to slip, leading to an invalid test.

The first response to slippage is often to increase the gripping force by over-tightening the mechanical grips or to increase the pressure of pneumatic or hydraulic grips. Although this may temporarily solve the slippage, it can also bring new problems:

• Simple screw action grips are often tightened with a spanner or wrench. It's very easy to exert high torque loadings to the load cell unless care is taken. Excessive tightening can easily damage low force load cells. Taken to extremes, it's possible to damage the grips themselves. Using a small torque wrench will allow you to achieve consistent gripping force.
• Increasing the pressure applied to the specimen by the gripping system can also increase the chances of influencing the mechanical properties. This is especially true of materials that are weaker in compression than in tension. We find that increases in jaw breaks often accompany increases in the gripping force.

Poor maintenance can result in uneven or inconsistent gripping. High-frictional losses in screw grips reduce the clamping force on the specimen for a given tightening force. Friction effects in wedge grips can induce bending if the faces move unevenly.

Here are some golden rules for reliable gripping:

• Regularly clean and lubricate moving parts with the correct grades of lubricant as advised by the manufacturer. This is especially important for wedge action grips, which rely on the smooth sliding of the jaw faces along an inclined plane for their correct function.
• Periodically inspect the grips for defects, such as cracks or leaks in hoses.
• Periodically verify that the pressure gauges are accurately registering air or oil pressure to the gripping system.
• Replace jaw faces when the surfaces become worn, damaged, or contaminated. Some jaw faces, such as rubber-coated types, can degrade over time simply due to exposure to air and light. This degradation can accelerate if the jaw faces are used under non-ambient conditions in an environmental chamber.
• Do not use more gripping force than necessary to provide reliable, slip-free gripping.
• Old grips don't necessarily work with new materials or specimens. You may find that special grips or different jaw face surfaces are needed. You can try a variety of things to modify existing gripping methods including emery cloths, sticky tape, etc.

Read more

Trends In Hardness Testing

Recently, Bill O'Neill - Director of Business Development and Sales for Hardness Americas - wrote an article for inclusion in Quality Magazine. Focusing on various methods to improve productivity, accuracy, and efficiency, we've included a short insert below. 

Consistent with the unprecedented advancing technology we all benefit from in just about anything related to computers, communication, digital vision, and hardware engineering, hardness testing has rapidly evolved in technique—more so in the past 20 years than any previous developments since the inception of this important materials test method. Limitations in regards to material geometry, surface finish, productivity, efficiency, data manipulation, and results reporting have been mitigated while continually undergoing enhancement. The result is increased ability and dependence on “letting the instrument do the work,” contributing to substantial increases in throughput and consistency, while freeing up the advanced operator for other responsibilities or allowing less experienced operators to handle hardness data acquisition. With the myriad of fully integrated systems now available, the labor intensive, subjective and error-prone processes of the past are virtually eliminated. More sophisticated, accurate and productive processes can quickly, reliably, and with extreme precision provide useful, material critical information.

Materials testing, including hardness testing, are useful processes for analyzing component properties and can be accomplished through a multitude of methods and techniques. Determining material hardness can provide valuable insight into the performance, durability, strength, flexibility, and capabilities of a variety of component types — raw materials to carefully prepared specimens to finished goods. In today’s extremely competitive global market, with high expectations on accuracy and productivity, quality and productivity errors have serious consequences. Manufacturing, research, and quality control now more than ever must depend heavily on new and evolving techniques to revolutionize more traditional processes if they want to maintain a competitive pace.

You can find the entire article here. Read more

Making Bricks

With Christmas fast approaching, many parents minds will be turning to toys for their children. The market is pretty cramped these days, but I'm particularly fond of an old household favourite: Legos. It feels like you can make anything from Legos now, with kits allowing the 'child' to build anything from municipal buildings to starships. But how are the bricks themselves made? How is the same excellent level of quality assured in every single brick?

The answer involves Injection Moulding; a commonly used technology for high quality, high demand products. Injection moulding uses plastic granules which are heated together into a thick ‘melt’. The melt is then forced under enormous pressure into finely detailed moulds, ensuring a supreme degree of accuracy.

But putting together an injection moulding process is no mean feat. One of the principal challenges of process design is matching the machinery with the raw material. Knowledge of the flow characteristics and thermal conductivity of the melt are invaluable in preventing poor mould filling and defects, which are both linked to poor product quality. In short, the mould designer needs to know how viscous, or thick, the material is and how quickly it cools. Once the process is designed and optimised, tests can be performed to ensure that incoming raw materials are of the appropriate quality.

The plastic used in Lego is known as Acrylonitrile Butadiene Styrene, or ABS for short, and has excellent mechanical properties. For simulating the injection moulding of ABS, or many other plastics besides, the SmartRheo range of Capillary Rheometer systems can be used. The machinery is adaptable and can readily be converted to perform rheology (flow), pvT (pressure, volume and temperature) or thermal conductivity testing as needs arise.

Just to finish, I’m going to leave you with some awe-inspiring Lego projects from around the internet!

Jet Turbine model

A REALLY tall tower

Chess board

Two-storey house

Custom printer Read more

Are Materials Testing Systems Potentially Hazardous?

They certainly can be. Material testing involves inherent hazards from high forces, rapid motions, and stored energy. You must be aware of all moving and operating components that are potentially hazardous, particularly the actuator in a servohydraulic testing system or the moving crosshead in an electromechanical testing system.

Whenever you consider that safety is compromised, press the Emergency Stop button. This will stop the test and isolate the testing system from hydraulic or electrical power.

Ensure that the test set up and the actual test you will be using on materials, assemblies or structures constitute no hazard to yourself or others. Make full use of all mechanical and electronic limits features. These are supplied to enable you to prevent movement of the actuator piston or the moving crosshead beyond the desired region of operation.

Your best safety precautions are to gain a thorough understanding of the equipment you are using by reading the instruction manuals, to always use good judgment, and to observe all Warnings and Cautions. You will find more specific warnings and cautions in the manuals whenever a potential hazard exists. Read more

Puncture Test on Pharmaceutical Bottle Seal

The Food and Drug Administration requires that many consumer goods, such as over-the-counter pharmaceutical bottles, be covered by an air-tight seal. This seal prevents harmful liquids, gasses, bacteria, and sometimes light from damaging the contents of the bottle. These seals need to be protective, but still easy for the consumer to open.

Although there have been many advancements to theses seals over the years, some are just down-right difficult to break open. Many times, without the help of a sharp object, users resort to poking the seal with a thumb or index finger - which, if you've tried it, can be rather difficult. Just how difficult is it to poke through these seals?

We put a few bottle seals to the test in our Applications Lab - watch this video! Read more

Impact on a Cosmic Scale

Instron makes enough impact machines that go bang not to be blown away by any old catapult, spud gun or ‘accelerator’. But there are some truly awe-inspiring projects out there that occasionally catches my interest, and I’d just like to show you a choice selection.

First off, VERA (Variable Energy Research Accelerator) is an advanced 'spud gun' that can deliver energies of up to 2.25 megajoules. That’s enough energy to fire a fully laden London bus over a five storey building! VERA functions using a combination of compressed air and combustion, which it contains using enormous tanks. 

Moving on, the Shock Compression Lab at Harvard University simulates impacts between celestial bodies. That’s right, they’re mocking up collisions between planets, moons and other space debris. The gas gun fires projectiles at 6000 miles per hour, and the resultant shock waves are studied in order to better understand cosmic scale collisions and their after-effects.

Moving onto our final offering for today, Punkin Chunkin is an annual effort for technically minded types to outdo one another – in the field of Pumpkin throwing! Machines are pitted against each-other by enthusiasts from all over the world and come in a number of varieties – a quick Google image search will give you a rough idea of the wealth of designs that come through. The competition is well into its 26^th year, and in that time the 'Chunkin' machines have grown increasingly capable – the record has steadily risen from a meagre 126 feet to over 4,400 feet in recent years! 

Our range of impact testing operates in a much more controlled manner, and can be used to analyse the process of impact and failure using strain gauges and high-speed data acquisition systems. Models are available for Quality Control and Research purposes and range all the way up to 1800 Joules. Check out more information on our drop towers our pendulums. Before embarking on an impact project, please make sure that proper safety precautions are in place. 

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Bandwidth & Data Rate: Whitepaper

We have discussed bandwidth and data rate a few times on the blog, but we find that it's an important topic to cover...

The US National Security Agency (NSA) collects surveillance data from satellites and by other means. The NSA supercomputers sort through billions of phone calls, faxes, emails, and radio transmissions; it has been estimated that five million emails are transmitted each minute and 35 million voice communications are completed each hour. Unfortunately, it takes some intelligence to cut through all the “chatter” – otherwise, you have inaccurate information and the results could be disastrous.

A similar situation exists in the data acquisition world. By definition, data acquisition systems are designed to gather and store data. However, this definition has led many managers and engineers to spend large amounts of money on systems that do just that - gather data - but are good for little else ...

Frank Lio, Support Manager for our Electromechanical Business, wrote a whitepaper on Bandwidth and Data Rate, and we have it here for you to download.

Topics included:
- The True Purpose of Data Acquisition
- Measurement Noise and Filters
- Bandwidth and Data Rate
- Bandwidth Effects on Accuracy, Repeatability and Reproducibility

What other topics would you find useful if covered in a whitepaper? Read more

Blogging from Birmingham

This week has seen Instron in attendance at ‘The Composites Engineering Show’. Held annually at the NEC in Birmingham (UK), it’s a great opportunity to showcase the combined talents of the Composites industry. This year exhibitors presented a range of technologies from rapid prototyping to CADCAM and robotic systems. Also in attendance were cars from the Red Bull racing and Honda Yuasa teams.

The star performer at our stand was the ElectroPuls™, which spent much of its time fatigue testing a rubber aeroplane from the Westmoreland stand! Supporting the ElectroPuls were the 9310 drop tower and the 5969 static testing frame. Respectively, these machines represent our Cyclic/Fatigue, Impact and Tensile/Compressive testing capabilities.

During the course of the event, we were approached about testing anything from car doors to concrete. To my mind, this perfectly demonstrates the breadth and diversity of the materials testing industry, and I think it’s a credit to the versatility of our machines that we talk about such a wide range of applications positively and with experience. If you have a testing requirement that needs filling, why not leave us a comment below and we’ll contact you?

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Advantages of a Twin-Bore Capillary Rheometer

Capillary rheometers allow users to better understand the processability of a thermoplastic prior to extruding or injection molding. This improves yields and reduces recycling/regrinding.  Also, the rheometer enables users to perform process optimization to improve productivity by better understanding a thermoplastic’s rheological behavior under specific test conditions.

These rheometers are available in single- and twin-bore configurations. The twin-bore systems offer some important advantages:

• First, the ability to perform two simultaneous and independent rheological tests at once increases testing throughput, which is invaluable in quality control testing.
• Second, it allows for the direct comparison of the behavior of two lots of the same material, or two different materials, which is of benefit to both the quality control tester and the researcher.

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Q. What is GR&R?

A. Gauge Repeatability and Reproducibility (GR&R) is the determination of the accuracy of a measurement by ascertaining its repeatability - the consistency of measurements taken by the same operator - and reproducibility - the consistency of measurements taken by different operators.

There are five major elements of a measurement system that contribute to errors in a measurement process: the standard, the part being measured, the instrument, the operator, and the environment. All of these elements affect the measurement reading obtained. Overall measurement errors are minimized if the errors contributed by each of these elements are minimized.

There are various ways by which the GR&R of a measuring system may be assessed. A common method is to first measure variations due to the measuring equipment. Variations are calculated from measurement data obtained by the same operator taking measurements using the same equipment under the same conditions. Subsequently variations are calculated from different operators taking measurements using the same equipment under the same conditions. Variations may also be calculated from measurement data obtained from several different parts. An overall GR&R value, called the %R&R, is calculated from these combined variations.

The measuring system is considered satisfactory if the %R&R is less than 10%. A %R&R between 10% and 30% may also be acceptable, depending on what it would take to improve the system variability. A %R&R of more than 30%, however, should prompt an investigation into how the R&R of the measuring system could be further improved. Read more

Biomimetics - Material Structure in Nature

The natural world is full of inspiration for the materials scientist. Many researchers are working in the field of biomimetics trying to develop synthetic materials that equal or even outperform materials found in nature. Many of these synthetic materials, while attaining similar specifications to the natural material, sadly fall short in performance comparisons. However, scientists are discovering that nature’s high performance is not due just to the basic material properties, but to the structure and form of the materials. Two cases in points are the scales of the Arapaima fish and the exoskeletal cuticle of insects.

Arapaima

The Brazilian Arapaima is a huge fish weighing up to 300 lb. It lives in lakes alongside the better-known Piranha. So how come it doesn’t become Piranha food?

This was the question that intrigued researchers at the Jacob’s School of Engineering at UC San Diego. They found that, as much as the Piranha would have enjoyed snacking on the Arapaima, their needle-sharp teeth were unable to penetrate the scales of this massive fish.

Investigation of the fish's scales structure showed that they are composed of an outer layer of a hard, mineralized biomaterial with an inner layer of softer collagen fibers. In other words, the fish is “case hardened”, offering a hard outer surface with a flexible inner core. The researchers carried out hardness testing on the scales using an indenter that held an actual piranha tooth at its tip. The tooth was able to penetrate partway through the scale, but it fractured before it would have damaged the underlying muscle of the fish. Further, the outer layer of the scales is corrugated giving the hard scale the ability to bend with the movement of the swimming fish.

Insect Cuticle
Researchers at the Wyss Institute for Biologically Inspired Engineering at Harvard University have been investigating the properties and the structure of insect cuticle.

Insect cuticle is a composite material comprising layers of chitin (a polysaccharide polymer) and fibroin (a protein). These materials are arranged in layers, similar to plywood. Mechanical and chemical interactions between these layers and the different materials give the cuticle unique mechanical and chemical properties. The researchers have developed a thin, clear film from similar materials and with a similar layered structure as insect cuticle. The material is composed of fibroin protein from silk and from chitin extracted from discarded shrimp shells. It is thin, clear, and flexible, and the researchers claim it is as strong as aluminum at half the weight. They have called the new material Shrilk.

One of the biggest advantages of this new low-cost synthetic material is its biodegradability. Shrilk could one day replace plastic for degradable consumer products, such as trash bags, packaging, and diapers, and be used safely in a variety of medical applications, such as sutures or scaffold for tissue regeneration.

Nature has always been an inspiration for materials scientists. Early man used natural materials, such as wood, bone, sinew, and leather to manufacture tools, clothing, and structures. Synthetic materials have improved on the properties of many of these basic materials, but for some of them the limits of their performance have been reached. Research into how nature constructs natural materials, as well as into their basic chemistry, offers the promise of attaining even higher performing synthetic materials in the future.

Images:

Arapaima image courtesy of George Chernilevsky in the public domain.

Grasshopper image courtesy of Gilles San Martin under a creative commons license.

Sources:

Piranha Vs. Arapaima: Engineers Find Inspiration for New Materials in Piranha-Proof Armor. Science Daily, Feb 8, 2012

Arapaima fish scales inspire new materials. robaid.com, Feb 9, 2012

Inspired by Insect Cuticle, Wyss Researchers Develop Low-Cost Material with Exceptional Strength and Toughness. Wyss Institute for Biologically Inspired Engineering at Harvard University, December 12, 2011

As Strong As An Insect’s Shell. Harvard Gazette, Alvin Powell, February 2, 2012

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Say it With a Video

Videos have a way of making testing tips tangible .... They bring to life the mundane step-by-step bullets on how to install grips properly or how to run a test. I'm not saying that bulleted lists or whitepapers are not a necessity when it comes to materials testing and learning; I'm simply pointing out that if you can "say" it with a video, then you should!

We have a dedicated YouTube page that hosts more than 65 Instron videos on biomaterials/biomedical, composites, metals, and plastics, as well as software and holiday-themed testing.

As we add to our video library throughout the year, I'd appreciate your feedback on what you'd like to see covered in a video or webinar. Read more

A Day of Caring

We find it important to stay active in our communities, to do what we can as individuals and as a company to help those in need. Over the course of  two days, we had 18 employees take a leave from work and assist a local organization - Girl's Inc. - in converting their living room into a technology center.

"This new technology center will allow Girls, Inc to run classes surrounding cyber bullying, social media safety, and math/science/engineering," said Christina McMahon, Instron Assistant Controller. "The first day of our project was a huge success. The passion, leadership & teamwork I witnessed are a fundamental reason why I love working at Instron."

Girl's Inc has been providing mentoring and the building blocks for young women to succeed and be “strong, smart, and bold” for 100 years.

Does your organization participate in community events? We’d love to hear your stories ……… Read more

Geometry and Stiffness: What's the Connection?

Last month we posted a blog article on compression testing various eggs and compared the findings of these eggs to each other. Although we were testing to see how much load an egg could uphold before cracking, I recently read an article were researchers at MIT, as well as a team of researchers at the University of Lyon in France, are using "experimental and theoretical methods to better understand how the geometry of nonspherical shells relates to their stiffness."

Read the article ...

Have you ever tested specimens to understand how their shape impacts their properties? Read more

The New Alchemy

Scientists are trialing transmutation for the modern age. No, not lead into gold, and no Philosopher’s stone is involved. A simple bacterium is proving to be an effective, yet peculiar agent in producing high-quality plastics ideally suitable for medical and disposable applications.

Previously, the bio-plastic PHB has been grown in glucose by microbes with disappointing results. However, trials using waste cooking oil instead of glucose as a raw material have shown a tripling in yield in the same time period. This is great news for the waste recycling industry and the environmental community, firstly because un-recycled waste oil can be a major hazard to freshwater wildlife, but secondly because PHB has very useful properties. This makes it suitable for use in a variety of applications and attractive to the polymer industry. Interestingly, some sources claim that PHB can be used as a component in bio-degradable sutures that do not need to be removed, but dissolve harmlessly.

Producing bio-polymers, such as PHB, in the past has been expensive due to the use of glucose as the feedstock. But given the relatively low-cost of waste cooking oil, the production process is not only more effective than with a Glucose feed-stock, but also much cheaper. This makes the production of PHB from waste cooking oil a breakthrough for the 21st century - environmentally friendly, but also economically viable.

This blog-post was inspired by an article posted here. Read more

Making an Impression... or Not

Every few years, scientists come up with a wacky new material with properties that defy all sense. As a case in point just look at the eerie ferro-fluids – liquids that respond to magnetic fields; or aerogels that can support the weight of a brick but weigh only 2 grams. Well, the latest ‘fad’ (if you can call it that) in ‘out-there’ science projects is a little something called a hydrogel. Hydrogels have been around since the sixties, but are more recently coming into their own in the bio-medical sciences. They hold a variety of potentially useful properties including the ability to self-heal and can be made from a range of polymers. But you’ve yet to see the most astonishing thing of all.

I should say first of all that we’ve seen plenty of impact tests. Our drop-towers will rip through many common household and industrial materials. But I was surprised to see this video. Ordinarily, testing a film (in plastics testing, any polymeric material less than 1mm thick is a film) is a somewhat delicate operation.

But not with this mysterious concoction of compounds, which can absorb impacts of 9,000 joules per square meter and stretch up to 20 times its original length without breaking. Just to give you some perspective – if a bag of sugar weighed 1 kg, and you had just a square meter of this hydrogel – you could drop the bag of sugar onto the hydrogel from nearly a kilometre above and not penetrate it.

We’ve already seen hydrogels performing well in a variety of applications including contact lenses, tissue engineering and nappies (of all things!), but until now their lack of sufficient mechanical properties limited their versatility for widespread use. But with recent developments producing promising results, the future is looking bright for hydrogels.

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Composite Cars?

Professor Dan Adams (University of Utah, Salt Lake City) has been at the forefront of the effort to bring composite materials into the automotive industry. The main driver behind this (no pun intended!) is the need to make cars lighter overall in order to reduce fuel consumption, all while maintaining or increasing safety.

Adams has been working with international organizations to develop unique and novel new “crashworthiness” tests and fixtures to better understand how composite materials will behave under impact conditions.

Check out this article… Read more

The Future of Green Fuel

Hemmed in by strong oceanic currents forming a ‘gyre’, the Great Pacific Garbage Patch is a stretch of relatively still water in which plastic waste gathers, floating just under the surface. Estimates of its extent vary from Hawaii-sized right up to twice the size of the United States. The ambiguity arises from complications in the sampling process and definitions of the problem area. Definitions are typically based on ‘above normal’ levels of pollution – although there is some sadness in acknowledging any level of pollution as normal, with the potential association that normal is therefore acceptable. The problem is also somewhat counter-intuitive; larger matter like bottles and containers are broken down by photo-degradation, due to exposure to the ultraviolet light found in sunlight. You might think this would help to dissolve the plastic but in reality, this only cuts down the size of the particles. The plastic, once broken down into millimetre-sized pieces can then take hundreds of years to decompose. Meanwhile, at the millimeter scale, the plastic is unfortunately perfectly sized and placed to find its way into the bodies of animals as diverse as Jellyfish, Sea Turtles, and Albatross. Often the plastic particles wash up on shore and ruin picturesque landscapes while causing a hazard to native wildlife.

Aside from ecological concerns, there are other serious issues facing the global community. In particular, the world economy is predominantly driven by crude oil, which is rapidly running out. Some estimates predict as little as 40 years of oil remaining. Wouldn’t it be great if we could solve both problems of ocean pollution and oil depletion with one sweeping motion? Project Kaisei seems to think so.

This non-profit organization is focused on the research of marine debris, particularly in the Pacific ocean. One of their long-term goals is to create technology to ‘harvest’ the waste plastic from the ocean so that it can one day become a useful resource. The idea of waste plastic as a resource could serve as a vital incentive to the world’s industry captains to clean up the seas. What happens when the material is actually harvested? This is where companies like Cynar come in. Cynar has developed highly successful technology for transforming used-up plastic waste into useful diesel fuel. So successful, in fact, that adventurer Jeremy Roswell is planning to fly from Sydney to London on 100% recycled fuel. But how does this process actually work?

First the recyclate is collected together in bales and sent to the central processing plant. There it is ground into small flakes, approximately 15 mm in diameter. Now the plastic must be transformed from a heap of flakes into a consistent fluid melt for processing at later stages. In practice this is achieved with an extruder, a machine fed by a hopper of plastic flakes that drives material through a heated screw mechanism. It is at this point that our testing machines come in to play. To achieve optimum efficiency and quality of product, the ground recyclate must be adequately tested so that the best extrusion conditions can be determined. This is particularly true in the recycling industry where the raw material can vary significantly in composition. The CEAST Series of Melt Flow Testers are well positioned to deliver this testing. Ranging from basic budget models all the way up to advanced, automated premium variants, our machines are easy to use and conform to the main international melt flow standards.

Once the material is melted, it is pumped by the extruder into the Pyrolysis chamber. Pyrolysis is a process of breaking down the long chain hydrocarbons into small constituent molecules similar to the raw crude oil from which the plastics were made. In order to do this, the polymers are heated at temperatures of up to 420° in the absence of Oxygen to prevent burning. The primary product of this process is a high-quality diesel fuel. Cynar produces 800 liters of diesel per ton of recycled plastic and even uses gases harvested from the process to power the process. The ‘synthetic’ diesel produced burns more ‘cleanly’ than regular diesel with a much better rate of emission production.

Could we see waste differently in the future? Could today’s eye-sores and environmental disasters be tomorrow’s gold-mines? Only time will tell. Read more

The Evolution of String

Taking a look at the evolution of string: From the legendary days of Robin Hood and his ability to handle a bow and arrow made out of hard wood and strings made from rawhide, linen or hemp to the bows and arrows of today, which are made from advanced composite material and synthetic fibers. 

Crary Brownell (Brownell & Co.) was one of the first to take a look at alternative materials for making bow string, both because he enjoyed the sport and because he owned a textile manufacturing facility. It is desirable to have a very strong and durable string with minimal stretch so that all of the bow power can be used to propel the arrow.

In 1928, Brownell introduced a string made from linen that was durable and had a low stretch. In 1957, he revisited the archery market and thought of improving the string performance by making it out of Dacron, which was a synthetic fiber made by DuPont. After some trial and error, Brownell was able to successfully use Dacron fiber to make strings for bows called Brownell’s B-50, which became the standard bowstring material well into the 1980s.

In 1985, Allied Signal introduced Brownell to a new fiber called Spectra and asked that they should try to use it to make their string. Spectra is much lighter and strong as steel, exhibiting very little stretch. Although it was a challenge to get Spectra to work well, Brownell’s engineers succeed, testing to ASTM Standards F1752 (Standard Test Method For Archery Bow Component - Cord Material) and ASTM F1648 (Standard Test Method for Archery Bow Component - Serving String Material). This product, Fast Flight, was introduced in 1986.

Over the last few years, Brownell  has been using High Modulus Polyethylene (HMPE), which is sometimes also referred to as Ultra High Molecular Weight Polyethylene (UHMWPE). This material has similar characteristics, but is lighter, stronger, and tends to be more durable. Additionally, Brownell developed blended fiber products from both HMPE and Vectran (a product of Kuraray Co LTD). Read more

What is the Bagley Correction and Why do I Need to Perform One?

When testing using a capillary rheometer, it is desirable to know the pressure drop along the capillary. Realistically, it is not possible to test for this inside the die itself, and pressure transducers are typically located just above the die. While this makes the machine design much simpler and more budget-friendly, it does introduce a very particular kind of error that affects readings of pressure drop, shear stress, and viscosity.

When the melt is pushed through the die, there are two drops in pressure that it experiences. First of all, the pressure drop due to the ‘entrance’ effects experienced at and around the die-mouth. This is related to the shape and size of the die and the compaction of the melt from a large to a small geometry. Additionally, there is a second pressure drop experienced between the start and end of the capillary. It is this second quantity that we are really interested in, and the separation of the two quantities is the product of the Bagley correction. The Bagley correction is unique for each configuration and set of parameters; it is only changed in die length that does not require a new correction to be performed.

Performing a Bagley correction might seem daunting, but it’s actually rather simple involving two basic rheology tests. Each test should be set up with identical parameters (a simulation of the anticipated testing conditions) and dies of the same geometry, but differing lengths. The analysis then consists of a mere pinch of high school algebra. Essentially, the two tests (ideally performed simultaneously on a dual bore machine) produce data that can be expressed as simultaneous equations:

E + A = x   (1)

E + B = y   (2)

Where E is the pressure drop due to entrance effects; A and B the drop in pressure in each barrel due to the lengths of the dies; x and y the pressure drop recorded by the transducers in each barrel. 

Then:

B = cA   (3)

Because:
1. The ratio of the length of one die to the other is known (c).
2.  The drop in pressure across the die is proportional to the shape, size and length of the die.
3.  The dies have the same shape and size.
4.  Thus the ratio of the die lengths is also the ratio of the pressure drops between the two dies.

Then taking equation 2 from equation 1:

A – B = x – y   (4)

A – cA = x – y   (5)

As c, x and y are known, you can now work back through the equations and calculate A, B and E. Software can be used to automatically perform the necessary calculations and execute a Bagley correction on all data collected following the procedure.

Having said this, if the data is purely for Quality Control purposes, then you won't need to perform the Bagley correction. As long as each test is executed using strictly the same equipment in the same configuration, then the results are comparable. 

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How Many Ways Can You Break an Egg?

This is the question we recently pondered with Ken Zuckerman of Pete & Gerry's Organic Eggs.

We tested 3 types of their eggs: Organic, Nellies Cage Free, and Marans Heirloom. Testing with a electromechanical testing system using compression platens the breaking force ranged from 37 lbf to 62 lbf. The Organic eggs broke with the least force - 37 lbf, while the Nellies broke with an average of 54 lbf. The mahogany Marans heirloom eggs were the strongest no matter which way we tested them.

Take a look at the video to see the tests. Read more

Question from a Customer

Q. How should I approach rheological testing with a new polymer?

A. The optimization of rheological tests is iterative; the best way to determine the most ideal testing conditions is to experiment with the material. That said, there are some basic questions that we can ask ourselves about the polymer in order to speed up the optimization process:

1. Is it thermoplastic or thermosetting? I would have serious reservations about performing a test on a thermoset; great care should be taken to discover the conditions that bring on thermosetting and then to meticulously avoid those conditions while testing.

2. Do we know the optimum temperature range for processing of the polymer? Many materials are listed in tables of Melt Flow Rate data, and temperature information from these tables is transferrable for use in a Capillary Rheometer. The key is to enable stable flow while imposing the intended processing conditions. If the material flows in an unstable manner, the temperature should be raised; if the material shows degradation, the temperature should be lowered. Temperature change should be of the order of 5-10 degrees per attempt and the selection of optimum processing temperature should be made on the basis of satisfactory performance of the extrudate. This may take several attempts.

3. How viscous is the material? Highly viscous polymers will need a large diameter capillary so that the test is not confined to a very low shear rate by the limitations of the pressure transducer. Conversely, low viscosity polymers, such as PVA, require the use of a much smaller die so that the barrel is not emptied before the test is complete. Often MFR data can help in making these decisions.

4. What pressure transducer shall I use? Until the first test is complete, it won’t be clear how much pressure the fluid will exert under test conditions. The most highly rated pressure transducer should be fitted; if the chosen transducer is too delicate it may be damaged. The results of this test will be of very low resolution, but will be accurate enough to determine a more appropriate choice.

5. What if I want to do a Bagley correction? A Bagley correction is a test using two barrels that calibrates the machine against the effects of barrel-die geometry. Because the Bagley correction is specific to the testing parameters under which it is performed, it is worth waiting until appropriate testing conditions are agreed upon before performing one. Additionally, initial tests should be run on a single bore. This in case the testing conditions prove to be inappropriate and the test must be aborted. Having filled only one barrel, only one barrel of material is wasted and less cleaning is required. Read more

Finding the Right Test Type

Part two of Why Test Composites touches on finding the right test type for your application. We cover the basics in this article; if you have more specific questions you'd like answered, leave us a comment below.

Composites are complex structures made from a variety of different plastic, metal, and ceramic materials. The mechanical and chemical integrity of composite materials are affected by many variables making property prediction and analysis challenging. Testing is a vital adjunct to analysis, as well as being essential for quality control. 
Rheology
The study of the rheological behavior of thermo-plastic based composites is very important for fabrication of end products and plays an important role in determining the material performance related to deformation and flow under the processing conditions. Capillary Rheometers measure the rheological behavior of thermoplastic polymers and composites under processing conditions. Melt Flow Testers measure, with great accuracy, the MFR and MVR - basic data required for thermoplastic quality control in the raw materials field.

Thermo-Mechanical
HDT & VICAT systems are used to characterize the behavior of plastic materials at high temperatures, measuring the heat deflection temperature (HDT) and the Vicat softening temperature (Vicat). These thermal testing systems range from very simple units for quality control labs to more advanced and automated systems.

Tensile     
Tensile testing of composites is generally in the form of basic tension or flat sandwich tension testing in accordance with standards such as ISO 527-4, ISO 527-5, ASTM D 638, ASTM D 3039 and ASTM C 297. A range of proven gripping solutions is available for ambient, sub-ambient, and high temperature testing. The gripping mechanisms include manual, pneumatic, and hydraulic actuation. A range of jaw face patterns are available to provide effective gripping of tabbed and un-tabbed specimens. This allows for no slipping under load and no premature failure caused by stress concentrations in the jaws. Hydraulic grip solutions for non-ambient testing place the hydraulic components outside the temperature chamber, for safety and reliability. Adapters are available to allow other accessories, including compression platens, and bend fixtures, to be attached while leaving the grips in place.

Compression
Compression tests can be conducted on plain or “open/filled hole” specimens.  Common testing standards include: ASTM D 695, ASTM D 3410, and ISO 14126. Compression fixtures are designed to meet the unique requirements of composite materials providing precise alignment and precision guidance to prevent buckling.

Compression After Impact
Significant advances in damage tolerant composites include the addition of sheets between plies and additives to the resin. A Compression After Impact (CAI) test helps develop and prove these damage tolerant composites and also the repeatability of their performance. A drop tower is required to provide the impact before a compression test is conducted on a testing machine. Standards include: Airbus AITM 1.0010, ASTM D 7136 and D 7137, SACMA 2R-94, and Boeing BSS 7260. Watch a video on CAI.

Flexure
The most common flex testing of composites is 3-point and 4-point bend testing to ISO 14125, ASTM D 790, and ASTM D 6272. 

Shear
Interlaminar, rail, in-plane Iosipescu, and flat sandwich in-plane shear tests can be performed to meet standards: ISO 14129, ASTM C 273, ASTM D 5379, and ASTM D 4255. ASTM D 2344 and ISO 14130 can also be met using an interlaminar flexural and shear testing fixture.

Fatigue
An extensive range of dynamic systems accommodates loads from < 1 - 2500 kN, ideal for meeting the  fatigue and fracture testing requirements of composite materials – especially in demanding applications such as aerospace and wind power. It’s important to note that the load frames need to provide high stiffness and exceptional alignment that composite testing demands.

Other Mechanical Tests
A variety of other standardized mechanical tests on composite materials are available. Examples include bearing strength tests to ASTM D 5961 and interlaminar fracture toughness tests to ASTM D 5538. Read more

Why Test Composites?

Composite materials are being used in an ever-increasing variety of products and applications as more and more industries realize the benefits and advantages that these materials offer as they strive to manufacture structures that are lighter, stronger and offer greater corrosion resistance than those made from traditional materials. As the demands for light-weight structures for the aerospace and automotive industries develop, along with environmentally sustainable energy systems, the physical and mechanical testing requirements for materials and components extend too. Composite materials and components require a range of physical mechanical testing, under a range of environmental conditions, including high-force tension and compression, impact, flexure, shear, rheology, and fatigue.

Mechanical testing instruments are configured with a range of fixtures that have been developed to provide various ways of testing composite materials depending on the type of material and its intended end-use. Most of these fixtures are designed to meet specific materials testing standards. These standards have been developed over the years by leading manufacturers and research organizations, and then made their way into ASTM, ISO, EN, and other standards. In addition, auditing bodies, such as Nadcap, dictate performance criteria, for example alignment for the testing equipment.

Material Properties – structural variables such as fiber orientation, fiber volume fraction, laminate thickness, and core density; and processing variables such as layup accuracy, curing temperature and pressure can have a dramatic effect on the mechanical properties of composite materials. Mechanical and process testing is necessary to understand the effect these variables have on the finished material or component.

Reliability – for use in high-performance applications in the aerospace, automotive, and motorsport industries, material testing is required to prove the reliability and repeatability of component properties.

Damage Tolerance – testing is necessary to simulate real-life conditions such as tool drops, minor accidents, and manufacturing imperfections.

Research and Development – testing is performed to investigate variables that will effect mechanical properties, damage tolerance, and provide data for finite element analysis. Read more

Developing Employees & Solutions

Accelerating the development of current employees not only instills confidence within that employee, but it adds so much value to the company. The Gordan Engineering Leadership Program "broadens the employees skill set and gives them a deeper understanding of your company's position in the market".

One of our newest engineers, Morgan Galaznik, attended this program at Northeastern University, graduated in August, and became Instron's first Gordon Fellow - congratulations Morgan!

Find out more about the challenges Morgan faced and the solutions she developed for Instron. Read more

Video: Capabilities in Materials Testing

Materials testing is an interesting field of science - discovering the potential of multiple materials for use in such a wide range of industries: academic, automotive, biomedical, construction, defense, healthcare, and more. Everything we use in today's world is, at one point, tested for durability, strength, and resilience. Take a peek inside the world of materials testing at Instron.

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Jostling in Judo

Judo, a martial arts represented at the Paralympic games, is more dramatic and competitive than normal when you consider that in the Paralympic version, the Judoka (the original Japanese word for exponents of Judo) are blind or visually impaired. Its system of throws, grapples, and take-downs lends itself to athletes who are visually impaired, but otherwise have no physical disability. With Judo mats that are typically textured, this helps aid the athletes in orientation around the arena.

It is these mats that provide the stability, traction, and impact absorption properties required to enjoy the sport safely. After all, take-downs hurt. Throws are as dramatic as being tossed over a shoulder, and sometimes, Judoka simply fall on their faces. To ensure that participants aren't injured during bouts, judo mats must be rigorously tested.

Read here to find out more about how martial arts equipment, in particular Judo mats, could be tested to international standards. Read more

Slamdunk Safely

After the second World War, many veterans returned with injuries that prevented them from leading the lives that they had led before the war. However, rather than allow this to stand in their way, a number of American veterans founded the sport of Wheelchair basketball as part of a program of rehabilitation.

Using very similar rules and regulations to basketball, Wheelchair basketball is every bit as intense and dramatic. The wheelchairs are specifically designed for resilience to the intense conditions seen on the court, but often last only six months. Even more significant is the risk of injury from competing in such conditions. Mouthguards are only recommended in the international rules, rather than required as mandatory wear. Without one, however, a simple fall could result in broken teeth and tongue injuries.

Even if an athlete does wear a mouth guard, how do they know that it will protect their teeth and tongue during falls and collisions? Read here for more on how drop towers could help. Read more

Blades of “Steel” - Carbon Fiber Rowing Oars

With more than 500 athletes racing down the course with precision during the 2012 Olympic Rowing Competition, each stroke of the carbon fiber oars are vital as the boats soar significant distances to the finish line.
Introduced in 1976, carbon fiber oars have significantly enhanced the sport of rowing. These oars enable crews to push their boats to faster speeds and to perform with extreme precision. Originally, crews used wooden oars that were bulky, stiff, and heavy (weighing 14 kilograms). Carbon fiber oars are lightweight (only weighing 5 kilograms) and can be tailored to athlete's specific needs.

Carbon fiber blades are produced by compression molding, which utilizes extreme heat and pressure to generate high-strength objects. First a fabrication of carbon fiber, pre-impregnated fiberglass and syntactic foam are poured into a heated compression mold (like a giant waffle iron). Then the mold is closed with nearly 6,350 kilograms of force. Once the blade has cooled, it is trimmed, painted with a design, and finished with coat of epoxy. Finally, the blade is tested for strength, flexibility, and durability to ensure maximum power and precision on race day. Read more

A Unique Sport

Goalball is an eccentric sport unique to the Paralympic games and is played by athletes with a visual impairment. Much like soccer, each team attempts to get the ball into the other team’s goal.  This is where the similarities end, however. In order to level the playing field completely, all competitors must wear eye-shades to completely black out their vision; the ball is perceived audibly and the court features a tactile surface to aid in orientation. The eyeshades must be thick enough to completely black out all light, strong enough to survive a rough sporting environment, and not cause significant discomfort to the competitor. Unfortunately, the process of injection moulding the eye-shades can leave flaws in the finished product:

• Bubbles can cause stress concentrations, which reduce the life-span
• Rapid solidification in the mould causes insufficient mould filling
• Elasticity of the melt during processing results in distortions
• Thermal degradation can affect the physical properties of the goggles, making them weaker

Injection Moulding is a popular choice for manufacturing high volume products, however, if it is not properly controlled, can lead to any number of the above flaws. Read here to find out how the CEAST SmartRHEO Capillary Rheometer can help your company enhance its injection moulding Research, Design, and Quality Control processes. Read more

Horse Riding in the Paralympics: A Dark Horse?

Horse-riding is an immensely popular sport, with an estimated 15 million horse-riders in Europe alone, the adoption of dressage in the Paralympic games in 1996 was inevitable, if not overdue. Dressage, from the French word for preparation or training, is an intricately choreographed performance where riders guide their own horses through a series of obstacles during a ‘test’.

There are several medals available from these tests, in team and individual formats, awarded by judges who score the riders based on individual movements and the routine as a whole. Paralympians participating in dressage are classified and given a grade according to the level of their impairment; the expectations of, and hence scoring by the judges are based on this grade level. Visually impaired riders can even use specially located ‘callers’ to help them find their way around by ear. The sport is generally safe and accidents are infrequent – however, falling from a horse can be very dangerous and often results in fractured limbs. For this reason, riders wear protective equipment, which must be stringently tested to ensure satisfactory performance in the event of an accident.

Read here how our drop-towers can be used to provide safety assurance for this classic sport. Read more

Recycling at London 2012

At any large event, an inordinate amount of rubbish is generated and the Paralympics is no exception – it has been estimated that 8,500 tonnes of rubbish has been generated just by the Olympics alone. With London 2012 being heralded as the first ‘zero waste games’, all of this rubbish will be winding its way to various recycling centres. Much of the material is in the form of plastic bottles, bags, and other forms of packaging.

Fortunately this type of rubbish can easily be recycled, in a process which involves sorting, granulating, blending, and melting the recyclate. From here, the material can either be recycled directly into new, low-quality product or ‘compounded’ with additives, colourants and virgin material into tiny pellets to be used as a raw material. The biggest problem faced by the compounder or recycler is the inconsistency of the material. Even materials that are technically the same may have been processed in different ways and exposed to different conditions which can affect chemical composition and physical properties. Primarily, the manufacturer needs to know the appropriate processing conditions in order to produce consistently satisfactory product.

One way of determining these conditions is to measure the Melt Flow Index (MFI), a quantity which is also useful in quality control processes. The MFI represents the amount of material flowing through a die of predetermined size and shape in ten minutes, and is measured as Mass Flow Rate (MFR). With knowledge of the melt density, the Melt Volume Rate (MVR) can also be calculated. Melt Flow Indexers measures MFR and MVR in an accurate and repeatable manner; the machines are ergonomic and computer controllable, ranging from the basic model to the advanced, automated, multi-weight machine.

Read here for more information regarding Melt Flow and Volume Rate testing. Read more

Cruising and Composites

The Composite Materials Handbook (CMH17) Meeting was held at MIT in Cambridge, MA the week of August 20, 2012. The meeting, held every 8 months in rotating locations, provides an opportunity for members to review the guidelines and technical information to standardize requirements for composite materials.

We were happy to take part in the hosting "duties" and took the attendees on a narrated boat cruise of the Charles River and Boston Harbor. We sailed through the locks from the Charles River to Boston Harbor and underneath the Leonard Zakim Bunker Hill Memorial Bridge – landmarks of particular interest for their engineering ingenuity.

The cruise was attended by members from the US, UK, Canada, Korea, Austria, Israel, the Netherlands, Brazil, and France.

Did you take a cruise around the harbor? Leave a comment below!

Information about CMH17
The Composite Materials Handbook provides information and guidance necessary to design and fabricate end items from composite materials. Its primary purpose is the standardization of engineering data development methodologies related to testing, data reduction, and data reporting of property data for current and emerging composite materials. In support of this objective, the handbook includes composite materials properties that meet specific data requirements. The Handbook, therefore, constitutes an overview of the field of composites technology and engineering, an area which is advancing and changing rapidly. As a result, the document is constantly changing as sections are added or modified to reflect advances. Read more

Sailing the Seas Again

Previously featured in one of our newsletters, the USS Constitution, nicknamed Old Ironsides for its extremely strong and cannonball-repelent surface, was a war ship during the War of 1812.

Over the weekend, the residents of Boston, MA commemorated the war's 200th anniversary. The highlight - the sailing of Old Ironsides, which reportedly is only the second time the ship has sailed (on its own) in more than 130 years.



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From Helmets to Sticks: Testing Hockey Equipment

For almost 100 years, hockey has been a favorite sport to watch in the (winter) Olympic games. With fans cheering for their favorite team or players, it's easy to get caught up in the rivalry and sport of the game, forgetting that it can be quite dangerous on the ice ... from flying pucks at top speeds to swinging sticks with great force. Luckily, the manufacturers of hockey equipment don't lose sight of these dangers and routinely test their equipment for various safety measures.

Watch this video to see how the equipment is tested to protect our favorite players.

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