Metals Tensile Testing Standards: ISO 6892-1, ASTM E8/8M for Strain Control

Brief introduction into some of the changes and updates to both the ISO 6892-1 and ASTM E8/8M tensile testing standards for metals and ambient temperature.

Metals Tensile Testing Standards - ISO 6892-1 ASTM E8/8M - Strain Control from Instron

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Instron Year in Review

We've created a Year in Review to highlight exciting moments of 2013. We want to keep you up to date on all aspects of Instron® – from our community relations to our acquisitions to available webinars, and new products. There was never a dull moment or a period of time when we weren’t aiming to meet the expectations and needs of our customers. Every experience you have with Instron is invaluable to us as a company. Specifically within TechNotes, I work with our application engineers and product managers to bring you the most relevant and industry-specific news that will assist with your testing applications. Instron professionals are some of the best in the industry and hold seats on many of the ASTM and ISO committees. It’s my goal to share with you their knowledge and experience in order to better support your testing applications. So keep the feedback and questions coming! I welcome any chance I have to speak with you on ways to better communicate just exactly what you’d like to hear. Thank you for your continued support as we move forward into 2014 and I look forward to future communications with you! Best regards, Denise Czerpak TechNotes Editor

Download Now: A Year in Review

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Testing Metals to ASTM E8 with an Automatic Contacting Extensometer

 

The ASTM E8 standard describes tensile testing methods to determine yield strength, yield point elongation, tensile strength, elongation, and reduction of area for metals. It applies to metallic materials in any form: sheet, plate, wire, rod, bar, pipe, and tube.

When performing strain measurements, such as the strain corresponding to the yield strength, we typically recommend an automatic extensometer. Using an automatic extensometer, such as the AutoX750, helps reduce operator influence on the test while also ensuring accurate data. You can see this more clearly in the above video. Read more

Energy-controlled Impulse Testing of Shoes

Shoe and shoe material manufacturers alike must be able to prove that their products will withstand a substantial amount of wear and tear before releasing them to market. Useful in this analysis is the ability to simulate the impact of a runner on the sole of a shoe. During a typical gait cycle, these impacts can be higher than 3kN for an adult runner. In addition to controlling the load with which an impact is generated, researchers may also wish to control the energy which is generated as a result of the impact. A testing machine, which can successfully cater to these requirements, must be able to create and maintain a repeatable impact of a certain energy over a prolonged number of cycles.

Custom waveforms were created to replicate the impact of actual gait cycles. WaveMatrix™  software allows users to create and import their own custom waveform in the form of a CSV file, achievable in Microsoft® Excel. Through this custom waveform tab, customers also have the ability to specify a very precise impact duration. The up-to-5kHz acquisition rate of the 8800 Controller enables the waveform to be precisely controlled in the magnitude of milliseconds. As materials testing machines usually have two main controllable transducers, Instron established a method for achieving the given energy requirement for each impulse. The Advanced Amplitude Control is a feature of WaveMatrix that is key to conducting energy-controlled impulses, using a combination of controller gains to make sure that the energy requirement is met for each iteration of the impulse. The combination of this feature, in conjunction with the Calculations Module, allows the ElectroPuls™ to test footwear based on constant load, energy or any other requirement included in the calculations portion of WaveMatrix. Read more

Instron TGT at IMSS Exhibit in Chicago

Anna Wynn will be at the RX for Success exhibit at International Museum of Surgical Science (IMSS) in Chicago on December 5th, demonstrating the LigaGen L30-4c bioreactor instrument. This exhibit is focused on introducing and educating students on cutting-edge technology in bioengineering and the health care industry. The exhibit will be hosted by the Museum of Surgical Science and shared through both museum events and traveling exhibit venues. Read more

Question From a Customer: How to Report Strain at Break Following ASTM D638

Question: I am following ASTM D638-10, and my 'strain at break' results are nearly half of what other labs are reporting for the same material. What is wrong?

Reply: If your material exhibits necking or inhomogeneous strain, ASTM D638-10 specifies that the extensometer needs to be removed at specimen yield. Once the extensometer is removed, nominal strain is calculated to specimen failure. The standard specifies this to avoid tests where the specimen begins to neck outside of the gauge length. A common misinterpretation is that if your specimen necks within the extensometer gauge length that the extensometer can be left on until failure. However, to be compliant with ASTM D638-10, the extensometer must be removed at specimen yield regardless of where the necking occurs, and nominal strain must be calculated to specimen failure.

When the extensometer is left on the specimen until failure, strain at break is calculated by the change in extensometer gauge length divided by the original gauge length. The majority of specimen elongation will occur in the narrow section of the specimen where the extensometer is attached. When removing the extensometer at specimen yield, nominal strain is calculated by crosshead extension divided by the initial grip separation. This method is how ASTM D638-10 specifies strain at break to be calculated. The majority of specimen elongation will still occur in the narrow section of the specimen; however, the entire grip separation is now being used as the gauge length. Thus, this causes lower strain at break results. We have found in our lab that strain at break results are almost doubled when leaving the extensometer on until failure.

We recommended having the other labs remove their extensometers at specimen yield and check their method to make sure they are using nominal strain to calculate strain at break. Read more

What is Digital Image Correlation (DIC) and How Can It Help Me?

Digital Image Correlation (DIC) is an analytical technique that compares images of a specimen’s surface during testing to generate full-field strain maps. This technology gives you more information than a traditional point-to-point extensometer or a strain gauge and allows you to see the complete story of the material’s behavior beyond the stress strain curve.

Scientists and engineers have found dozens of useful applications for DIC including detecting cracks invisible to the naked eye, visualizing localized necking and discontinuous yielding, comparing differences in material behavior between two separate formulations, and analyzing strain on parts or components where a traditional extensometer is not feasible.

In our lab, we recently performed a test to ASTM standard D5766 for the open-hole tensile strength of polymer matrix composites and used DIC to see exactly where the strain was occurring. Using DIC, we were able to visualize where the strain on the specimen was concentrated and how it propagated through the material.

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Calling all Hockey Players: How Safe & Durable is Your Equipment?

Imagine being struck by a hockey puck traveling 100+ MPH while on the ice. As is the daily grind of hockey players everywhere, they rely heavily on the gear they choose to protect their bodies.

“We are seeing a trend in hockey equipment today that focuses on equipment being lightweight,” explains Olivier Jajko, Product Engineer at Warrior Sports, a leading global sporting goods manufacturer. “What customers may not know is that in order to reduce the overall weight of the equipment, some manufacturers are reducing the amount of material used."

Ultimately, that means less coverage for the player. This trend – this focus on the removal of equipment parts to make it lighter – is something Warrior does not take part in. In fact, they focus their experience and knowledge on developing smarter, more intelligent materials. “It’s important that we quantify the material stiffness and maximum loads that our products can withstand. We strive to keep the weight of the equipment down, but are not willing to sacrifice the protection of the players,” says Jajko. During the new product development cycle, Warrior tests the materials to determine stiffness, as well as strength at failure. This helps ensure that the right materials are selected and the players are securely protected. Once the finished product is created, the design and finished component must be re-evaluated.

In addition to following this trend of product development, Warrior Sports is also maximizing product safety. They recently developed a two-way protective padding – SmartCap – which is the first of its kind. The patent-pending padding not only protects the players from bumps and hits during a game, but also protects the opponent during contact. This type of innovative design is helping to make hockey a safer sport without entirely changing the nature of the game. Read more

Challenges with Steel

The continual drive for improved safety and increased fuel efficiency within the automotive industry hasn't escaped anyone; the message is repeatedly broadcast via news outlets and advertised by auto manufactures themselves. The majority of new car models compete fiercely for the most impressive fuel efficiency (mpg or L/100km) figures in class. As auto manufactures strive for improved fuel economy, it is clear that material selection will continue to be an important factor in weight reduction.

One route that is being aggressively investigated by auto manufactures involves increasing the strength and formability of steel. Increasing the strength of steel allows the safety requirements to be met while reducing the mass (or gauge/thickness) of material used. In 2010, the mass of the typical lightweight vehicle was reported to be 1,752 kg (3,863 lbs.); of that, 58% was steel. Although the estimated mass savings from utilizing new designs of high-strength steel vary, a structural mass saving of 39% has been reported.

These new generations of Advanced High Strength Steels (AHSS) introduce additional challenges, such as gripping and strain measurement, when performing a tensile test. As material strength increases, typically hardness also increases, and this leads to gripping challenges around grip slippage and premature wear of jaw faces. In order to reduce the likelihood of slippage during a tensile test, high clamping forces can be utilized at the initial stages of the test. Using a hydraulic wedge grip design gives an ideal balance of adjustable initial gripping pressure to prevent premature failure and, if desired, fixed proportional gripping as the test load increases. With the increased strain seen in Twinning-Induced Plasticity (TWIP) steels and high tensile strengths seen in Martensitic (MS) steels, a highly accurate yet robust extensometer is required for the measurement of potentially relatively high strains (compared to other steels). This combination of hydraulic wedge grips and an automatic extensometer offer the ideal solutions for the latest generations of steels. Read more

Question from a Customer: What tup do I use on my 1,800 J (1,330 ft-lb) drop tower?

As a starting point for this response, the 1,800 J is the impact energy that your drop tower is capable of reaching. Selection of which tup to use does not have as much to do with the impact energy as it does with the way that the sample being hit reacts to the impact.

For example, if a sample is made from a piece of tissue paper – I can impact that with 1800 J of energy and the load produced from the impact will be in the 10’s of foot-lbs. However, I can then insert a piece of ductile steel of the same dimensions, impact it with the same 1800 J and reach a load in the 200,000 ft-lbs. Both samples have been subjected to the same impact event – however, each reacts differently. So proper selection of a tup is more a factor of the material being tested and the anticipated maximum load from the impact event. Read more

Carbon Fiber Hits The Road

The Drive for Lightweight Cars

By 2016, the US car industry will need to average 34.5 mpg and by 2025, cars will need to average 54.5 mpg. In order to meet these new requirements, manufacturers will have to implement a number of changes including new engines, technologies, and materials. Lightweight materials are one of the most important avenues to pursue because for every 10% reduction in weight, fuel efficiency is increased by 6–7%.

The Benefits of Composites

Carbon fiber composites are as strong as steel, while weighing over 75% less. The materials are the lightest to use and also the stiffest. Because of their superior mechanical characteristics, cars built using carbon fibers are some of the lightest, fastest, and most fuel efficient vehicles on the road. Composites can also absorb a large amount of energy before failure, which can make new lighter vehicles just as safe as their heavier counterparts. The only drawback is that composite materials are three times more expensive to make, meaning adoption will be slow until the price comes down. Despite the high cost, composites have been used in cars for over 30 years and are now being used for the first mass produced composite vehicles.

 

Composites in Use

Carbon fiber was first used in high performance vehicles such as the McLaren MP4/1, the first Formula One car to feature a carbon fiber chassis. The low weight and increased strength helped make the car one of the lightest, stiffest, and fastest to grace the track in 1981. The use of composites also allowed the engineers to design a safety cell for the driver, which would remain intact in the event of a crash, making previously fatal crashes survivable.
 

Over the ten years from 1981 to 1991, carbon fiber was used only on racecars because they were the only customers willing to pay the high cost for increased performance. The first carbon fiber vehicle to be sold to the public was the McLaren F1 in 1992. The million dollar sports car was built to be used on public roads but was truly at home on the track, hitting top speeds of over 200 mph and boasting a 0–60 time of just 3.2 seconds. Even with these impressive numbers, the car only weighed about 2,500 pounds (significantly less than most consumer vehicles) because of the low weight of carbon fiber.

Now carbon fiber can be found in many consumer vehicles from high-end manufacturers, but these vehicles are either low volume (such as the 400 unit Bugatti Veyron) or only use a small amount of carbon fiber.

Next year will mark a new milestone in automotive carbon fiber as BMW will begin selling the i3, the first mass produced car with a carbon fiber chassis. While previous cars used carbon fiber to save weight and go faster, the new BMW i3 will use carbon fiber to save weight and go farther. The all-electric car will tip the scales at 2,700 pounds—including the large battery needed to give it a range of 80–100 miles.

These new cars may be the first of their kind, but they won’t be the last.

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Who Should Be First in Line to Receive a Transplant Organ?

Tissue Engineering and Regenerative Medicine therapies are seeking to abolish this question.  Researchers around the globe are developing new scaffolds (materials on which to grow cells), identifying appropriate cell lines to use for specific tissues, and perfecting the recipe for putting the two together to grow new tissues and organs for transplant.   Instron is a part of this recipe.  Our mechanical systems and bioreactor chambers provide a controlled environment to develop new tissues and organs. The bioreactor chamber provides a closed, sterile location to house the sample; while the mechanical forces can be used to send mechanical cues to the cells to assist with differentiation, characterize native tissue and scaffolds, or evaluate tissue engineered products. Read our TERM (Tissue Engineering & Regenerative Medicine) Update to learn more about Instron's activity in this market. Stay tuned for more application updates.

Photo courtesy of Dr. Harlad Ott @ Massachusetts General Hospital:  Lungs being decellularized in an Instron TGT bioreactor chamber.

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Poisson's Ratio Testing With A Biaxial Extensometer

Poisson’s Ratio has proven to be a challenging calculation for obtaining both repeatable and accurate results. To improve repeatability, we typically recommend grips that provide consistent clamping pressure, such as pneumatic side acting grips. In addition, alignment devices can be mounted on these grips to ensure that specimens are identically aligned for each test. An extensometer with appropriate accuracy is critical for achieving reliable results. For both ASTM D638-10 and ISO 527, the extensometer must be capable of measuring the change in strains with an accuracy of 1% of the relevant value or better. For Poisson’s Ratio testing, we recommend using a biaxial extensometer. When testing with the biaxial extensometer, it is important to ensure that the top of the device is parallel to the grips and the device body is perpendicular to the grips. Essentially, it is critical to have the extensometer positioned straight when attaching to the test specimen. We also recommend carefully draping the extensometer’s wires and cords to remove any effect of additional weight hanging off of the extensometer.

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Simulating a Spring with the ElectroPuls

As the number of patients seeking “in-home” medical care grows larger, medical device companies find themselves catering to an increasing demand for safer, more user-friendly biomedical solutions. 

In an attempt to mitigate the injection process, medical device companies have developed the auto-injector, a spring loaded syringe that delivers a prescribed amount of drug subcutaneously into the bloodstream, forgoing the need for physician oversight and allowing patients to self-administer medication from the comfort of their own home. To design the ideal auto-injector, the delivery time of the syringe must be optimized so that drug release is neither too long nor too short, thus reducing the level of discomfort experienced by the patient. The delivery time can be optimized by choosing the appropriate spring and preload for a given syringe/drug system, which is currently achieved by subjecting springs with varying degrees of stiffness to different loads. However, medical device companies need to be able to get through this iterative auto-injector design process more quickly, and testing a large number of springs is time consuming and less than economical. Simulating the spring eradicates the supply chain issues of multiple springs testing, thereby significantly reducing the required design time. Instron solves this control challenge using Modal Control, an advanced feature of the 8800 controller that creates a composite channel to allow the applied load to vary with actuator position. The user simply needs to specify the initial preload and spring stiffness in order for the system to adjust itself based on the actual load seen by the syringe. A force vs. time graph is produced, from which the Calculations Module feature in WaveMatrix, determines the dispensing time and stall force of the syringe. The user can then determine if the chosen parameters for spring stiffness and preload have yielded an ideal auto-injector dispensing time for a given drug. 
 

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Upper Yield Calculations—Discontinuous Yielding / YPE Material

Following a recent lab visit, I thought it was worth writing a quick post to share an example of how labs sometimes incorrectly calculate yield strength. While visiting a testing lab for unrelated issues, my colleagues and I were discussing how the customer runs both continuous and discontinuous material with the same method (Non-YPE and YPE). For historical reasons, they have updated their Series IX methods to Bluehill 3 with little knowledge of why, when or by whom the methods were setup.

It later transpired in the conversation that some of the lab's material was falling below their specification for yield strength. They are required to test every coil of product before shipment; therefore, materials not meeting the yield strength requirement are of major concern. The material has had to be reworked in the past in the hopes that the yield strength could be increased slightly. Otherwise, the material would be scrapped.

The calculation used for both continuous and discontinuous material was an offset yield of 0.2% strain. Based on this calculation the stress values were determined for product verification. For a continuously yielding material, it is recommended to use the offset yield calculation. However, for a discontinuously yielding material, using this calculation would result in an inaccurate measurement of stress after a potentially significant load drop. The main international metals standards such as ISO 6892 and ASTM E8 both recommend using upper yield strength (ReH or UYS) to calculate this value correctly.

By changing the software algorithm to a different Bluehill 3 standard calculation, we were able to increase the calculated yield strength by around 10%. This meant they no longer had to rework the material as the higher stress values were always well within specification. This modification to their test method helped reduce testing turnaround time, increased the reported material strength, reduced shipment delays, and removed the need for costly and time-consuming reworking process.

The graph below shows an example of how the two calculations differ. The results of the offset yield calculation were on average 21% lower than the upper yield calculations. Checking that calculations are correctly evaluating data could result in a significant improvement of results. Often methods were setup and have not been reviewed on a regular basis.

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What Does Load Measurement Accuracy of 0.5% of Reading Down to 1/100th, 1/500th, 1/1000th of a Load Cell's Capacity Imply?

First of all, there are two important pieces of information here:

(1) Load accuracy: ± 0.5% of the reading

(2) Lowest possible load within this accuracy: 1/100, 1/500, 1/1000 of load cell capacity

For example, let’s assume your test system has a load measurement accuracy of ± 0.5% of reading down to 1/100th of the load cell’s capacity. When a load cell of 10 000 N (10 kN) capacity is used on this test system and a measurement of 1000 N is read, the actual load measurement can be any value from 995 N to 1005 N. For this 10 kN capacity load cell, the minimum possible load that is guaranteed to meet the load accuracy of ± 0.5% of reading is 100 N.

Now, imagine you have a newer system with a new 10 kN load cell and the load measurement accuracy of ± 0.5% of reading is now extended down to 1/1000th of the load cell’s capacity. The load measurement accuracy of ± 0.5% of reading remains, but now the minimum possible load that is guaranteed to meet the load accuracy of ± 0.5% of reading is extended down to 10 N.

So what does a larger load accuracy range mean to you? Here are some of the benefits you will see:

- Less initial cost since less load cells are needed

- Lower subsequent service costs as fewer load cells need to be verified annually

- Less operator error and improved throughput (number of specimens tested per hour) by not having to change load cells between different test types such as tensile and flexure tests.

- Higher confidence in test data for low load tests.

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Industry Insights Series: David Fry

Working alongside our friends at AZOM, they developed a series of engaging interviews with a few of our global colleagues. In the recent series, I was able to discuss metals testing requirements with a focus on the latest European metals standard, ISO 6892 and high precision strain measurement with the AutoX750.

We'd appreciate hearing from you some suggestions for additional interview topics that would benefit your testing and applications. Read more

Instron at Tissue Engineering Conference in Istanbul

 

Instron TGT went on the road for the TERMIS (Tissue Engineering and Regenerative Medicine International Society) meeting in Istanbul, Turkey at the end of June. Despite the "social unrest" in Istanbul, the conference was well attended with over 500 attendees from around the world, including Argentina, Chile, Korea, Russia, and New Zealand.

We introduced our combination of products, with a demonstration of the 5944 and Bluehill^® and the LigaGen Bioreactor System. The attendees were excited to learn about the acquisition and the new solutions that Instron could provide to tissue engineering and regenerative medicine. We estimate that 30—40% of the researchers were familiar with Instron, including those already using Instron systems to characterize materials for tissue engineering or to test and characterize tissue engineered products.

Tissue engineering conferences are an exciting combination of disciplines and this one was no exception. An array of topics were covered, ranging from Biomaterials; Scaffold Designs and Fabrication Techniques; Tissues & Cells; Stem Cell Science; Genetic Modifications; and Bioreactors.

We look forward to attending the remaining 2013 regional meetings in Shanghai (October 23—26) and Atlanta, GA (November 10—13).

Want to know what tissue engineering and regenerative medicine is all about? Check out Dr. Atala's TED talk on bioengineered tissues. Read more

Equipment Considerations for a Well-aligned Test

When testing stiff or brittle materials, such as composites, alignment is crucial—even instances of slight misalignment can throw off test results.

Misalignment in test frames takes two forms: concentricity misalignment, where the centerline of the upper grip/fixture is offset from the centerline of the lower grip/fixture, and angularity misalignment, where the two centerlines are at contrasting angles. Both forms cause extra stress on the specimen and can affect mechanical properties such as modulus, maximum elongation, and tensile strength.

The alignment of a system is so critical to test results that organizations, such as Nadcap, strictly regulate misalignment. To meet these requirements and reach the most accurate results, the test operator needs to carefully assess his or her station, including the testing frame itself to the alignment cells used to verify alignment.

In addition to being accurately aligned, the frame should also be stiff so that it deflects very little at the load.

Next, it’s necessary to align the frame with the grips that will actually be used. This means that if an alignment is performed with one set of grips, but then replaced with a second set of grips, both sets of grips must be realigned. (To prevent removing grips, it is helpful to choose grips that can accommodate multiple tests including compression.)

Rigid and symmetrical grips produce the best alignment results. Under load, symmetrical grips will deform symmetrically from front-to-back/from side-to-side; therefore, the grips will not bend the specimen. Plus, the more rigid a grip is the less it will deform under load.

Once the frame and grips are aligned, now the specimen needs to be aligned. The operator oversees this process. To minimize user error, grips with specimen stops indicate where to place the specimen every time. If the specimen is loaded in different positions, even in a perfectly aligned system, large variation will occur.

To ensure that platens are parallel to the degree that Nadcap requires, one rigid platen and one locking, spherically-seated platen are required. These types of platen can be compressed against each other to ensure that they are parallel and can then be locked to prevent them from being misaligned.

Alignment cells are an essential part of any alignment. These cells, when used in conjunction with software, provide valuable information on how to correct a system’s misalignment. The dimensions of the cell should be as close as possible to the specimens being tested. On occasion, standard or stock alignment cells do not fit with the samples being tested. In these instances, the design of a custom strain-gaged alignment cell may be necessary. Since fabricating a strain-gaged alignment transducer can be a time-consuming process, plan this step well in advance.

Any given system has small misalignment errors due to tolerances of the frame and the parts used. To adjust for these small errors, it is helpful to have a fixture which can be used to make small adjustments to the concentricity and angularity of the load string. This is especially handy for future alignments and will save you time and effort down the road.

As always, feel free to contact us with any questions. Read more

Question from a Customer: Bagley Correction

Question:
Can we compare viscosity results between polymers tested at the same temperature and identical shear rates but on two different capillary rheometers?

Answer:
As an example, let’s consider two capillary rheometers with the following specifications and test parameters.

Rheometer A:
Barrel diameter = 9.55 mm
Capillary diameter = 20 mm
Capillary length = 1 mm
Test temperature = 150 C
Shear rates = 100, 200, 300, 400, 500 1/s

Rheometer B:
Barrel diameter = 15 mm
Capillary diameter = 10 mm
Capillary length = 1 mm
Test temperature = 150 C
Shear rates = 100, 200, 300, 400, 500 1/s

Results obtained from a single test performed each on Rheometer A and Rheometer B are generally not comparable.

In order to compare any number of viscosity results from two or more different capillary rheometers, it is very important to normalize the pressure data by introducing a correction called Bagley Correction post testing. This correction applied to the pressure data will generate true viscosity values which will then be comparable between different capillary rheometers. This correction is necessary because of the “entrance effects”, which occur when the molten polymer is pushed through the larger barrel diameter into the smaller capillary diameter. These “entrance effects” generally are different between Rheometers A and B. The Bagley Correction compensates for these differences, thereby making the results between the two comparable. To find out more about the Bagley Correction, and how to apply it, please refer to this blog post. Read more

Instron at Alabama Composites Conference, Birmingham

Instron was at the Alabama Composites Conference (ACC) from June 19—20 in Birmingham, Alabama. Southeast Applications Engineer Jim Gleason and Kent Wallace, Dynamic Systems, were on site. ACC is held every two years at the University of Birmingham, Alabama (UAB) and focuses on latest innovations in the composites industry. Instron is proud to support such an event because it sees participation from a wide range of industry partners working with composite materials.

We exhibited an ElectroPuls E1000 and had a few Instron personnel at ACC to give information about our other product lines like electromechanical systems, CEAST impact machines, hydraulic systems, etc.

Check this out for an array of topics covered during different sessions of this conference. I found the ENERGY, GREEN, and BIOCOMPOSITES section very interesting in terms of using natural fibers as reinforcements to the matrix.

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A New Long-Term Bypass Solution

Today, heart disease is so common that it’s a fair statement to make that you or someone you know has been affected by this illness. It’s estimated that more than 17 million people around the world lose their lives to heart disease every year, according to the World Health Organization. And in the US alone, more than 500,000 of those patients undergo bypass surgery. Most surgeons will “borrow” blood vessels from another part of the patient, such as the mammary artery or saphenous vein; another option is to use a prosthetic graft material. Tissue Engineering will soon provide the superior option, replacement parts made from the patient’s own cells.

While prosthetic and “borrowing” the patient’s veins are popular and familiar choices amongst bypass patients, there is risk involved. The prosthetic grafts have the chance of rejection by the body because they are not natural and are foreign to the body.  Also, the plastic material has been shown to increasing clotting and/or become infected, resulting in additional hospitalization. Using existing veins/arteries is limiting as the supply is not endless, as many as 40% of bypass patients are unable to choose this option due to disease or previous use.

Tissue engineering  – a process that makes replacement blood vessels, in vitro, a reality – allows for a long-term solution for bypass patients. A patient’s cells are grown on a 3D scaffold, which could be natural or a manufactured material, in an environment that is similar to the body. The resulting tissue is then implanted in the patient. With tissue engineered parts, you are not “borrowing” from other areas of your body reducing the concern about availability and because the concern for rejection is obsolete, because the patient’s body recognizes the cells as its own.

To be successful, tissue engineered implants must be both biologically and mechanically similar to native tissue.  This means that the scaffold material and the end products are tested and characterized using tension, compression, and other forces to make sure that they can endure the physical strains of implantation.  Research has also shown that growing tissues under these same mechanical forces (exercising the tissue) results in a tissue similar to native tissue.

In addition to heart disease treatment, tissue engineering has the ability to change modern medicine in many different areas.  Pediatrics is a special case.  Current mechanical medical devices are able to “cure” pediatric disease and defects; however because the patients are babies and their bodies are growing quickly, the surgery must be repeated many times to correct the size of the device.  Tissue engineering offers a solution that can grow with the patient and minimize the number of invasive surgeries necessary. Read more

Google for Test Results

There are many situations where we need to analyze test results, not just from one sample file, but results that are spread across different sample files that were tested at different times with slight differences in setup or calculations. Are you ever in a situation where you would like to have all the relevant data together without spending a lot of time going through multiple files and copy-pasting the results? The answer to this lies in storing your results in a database. Unlike a file-based system, database storage is optimized for search and retrieval of information. It allows you to quickly narrow down to the right data set within seconds and it saves your search criteria for future use. This decreases the amount of time lab operators spend on moving and organizing data, while increasing the productivity and throughput of the lab.

Earlier this month, Parasar Kodati, Software Product Manager, hosted a live database management webinar. If you missed the opportunity to see it live, you can now take advantage of watching the webinar at your convenience.

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Question from a Customer

Q: Do you have the necessary equipment and expertise to adjust and verify Instron equipment to accuracy levels demanded by national and international standards such as ISO and ASTM? Do your verification/calibration certificates report measurement uncertainty for each measurement taken?

A: Our verification certificates report calculated measurement uncertainty for each measurement taken and are in compliance with the International Laboratory Accreditation Cooperative (ILAC) Policy for Uncertainty in Calibration. Instron Service personnel are factory trained to setup Instron equipment to meet and exceed these standards.

It should be noted that most Instron equipment can operate to specifications that exceed international standards. Our staff is equipped with calibration standards having the low uncertainties of measurement required to verify performance of Instron systems beyond levels found in many international standards. Many calibration suppliers do not have standards with the accuracy required to verify to these levels. For example: Instron maintains a primary force standard that is transferred to our deployed working standards – the need for a secondary standard is eliminated, the “chain of calibration” shortened, and measurement uncertainty is reduced.

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What is Stress Whitening, and How Can It Impact Your Test?

Thermoplastic polymers may exhibit a change in color under tension.  This phenomenon is known as stress whitening and may occur in both semi-crystalline and amorphous thermoplastics.

What is really happening here?

When an axial load is applied to a thermoplastic, the polymer chains reorganize during stretch.  The polymer chains will straighten, slip and shear within the plastic’s microenvironment.  In some cases, occlusions or holes are formed by the movement of fillers and the polymer chains.  Together these occlusions form microvoids.  When microvoids cluster to a size greater than or equal to the wavelength of light (380-750nm), the transmitted light is scattered and the object appears white.  Thus, the microvoids change the refractive index of the plastic.

It is important to understand stress whitening when measuring strain after yield with a video extensometer.  When testing with a video extensometer, contrasting dots are used to track specimen strain (i.e. white dots on a black specimen).  In a stress whitening plastic, a dark specimen marked with white dots will change color after yield.  In this scenario, the video may have difficulty tracking the dots and a more complicated marking solution would be needed.  An alternative solution for measuring strain after yield in stress whitening plastics is to use a high travel contacting extensometer, such as the AutoX750. Read more

Acquisition Responds to Customer Needs in Regenerative Medicine Market

Instron is pleased to announce the acquisition of Tissue Growth Technologies (TGT), a premier supplier of commercial bioreactors to grow and stimulate developing tissues. This alliance offers an instrumentation platform that is uniquely designed to cater to all aspects of tissue engineering, including evaluating cell function, in the emerging regenerative medicine market.


TGT’s modular DynaGen® growth systems have been developed in response to customer demands and provide the capability for repeatable tissue growth. The instrumentation can be configured with samples driven from a controller and computer. This platform sets the standard for mechanically stimulated tissue growth systems.






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Instron at the World's Largest Wind Turbine Testing Facility

Danish Prime Minister Helle Thorning-Schmidt helped to usher in a new era for Siemens Wind Power with the world’s largest testing facility for wind turbines, featuring Instron systems.

With locations in Aalborg and Brande, the new Siemens testing center is a global leader due to its footprint comprising over 27,000 square meters and its advanced testing abilities.  The facility is part of a one billion krone investment in Denmark’s wind turbine industry.

Watch the inauguration, including footage of Prime Minister Thorning-Schmidt learning about a 5900 Series system (hosted by TV MidtVest). Read more

Analysis at Every Stage of the Plastics Lifecycle

In their April Issue, Plastics Engineering has shared insight on Instron’s investment of analysis for every stage in the plastics lifecycle. As Instron develops new products, a heavy emphasis is being placed on improving efficiency and increasing production without sacrificing quality. Automation, among other things, helps to remove manual errors and in turn, provide more consistency and repeatability.

The AutoX can perform multiple types of tests with high accuracy and travel. The TrendTracker™ is a results management software package that allows the user to search, view, and compare multiple test results generated over time.  Responding to customer needs, the CEAST HV500 can be used to test specimens at temperatures as high as 500 °C and a low-cost Carousel Automated Feeding System can carry out tensile, tear, and t-peel testing of thin-film plastics. Read more

United Way Honors Instron for 2012-2013

The United Way has honored Instron again this year in recognition for the 2012—2013 campaign season.

At the Worldwide Headquarters, Instron received the Cornerstone Award for superior volunteerism in addition to the Most Improved Business Campaign Award for the third year in a row.  Where Instron’s Industrial Products Group was recognized with the Platinum Award, the highest level of recognition for donations for the second year in a row, the Instron Binghamton (NY) Facility was praised for its leadership.

As a company, as part of our communities, we are proud to contribute in the ways we can. Read more

Instron Supporting Britain's Economic Growth

The BBC sheds light on where to place bets for Britain’s future economic success. The recent segment displays a repertoire of Instron’s single column 3300 machine, dual column 5900 machine, and Bluehill® software running tests at the Tissue Regenix laboratory.

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The Evolution of Composites Testing

In insights from industry, Ian McEnteggart, Composites Manager, talks to AZoM about key processes in today’s composites testing world and how they are transforming the application for composites. Ian shares the value of unique testing methods, specialized instrumentation, and meeting national standards.

Instron equipment is widely used for testing composites, able to perform over 100 different test types on composite materials.

Ian has been contributing to Instron for over thirty years and specializes in this growing market. He holds a degree in physics from the University of Birmingham and a diploma in systems engineering. His background boasts of designing materials testing systems, developing international standards, and being published worldwide.

Read on to learn more.

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Protecting Your Investment: The Instron BioCoat

Do you perform mechanical testing with an Instron BioPuls Bath, a homemade bath, or with wet specimens? Medical devices and biomaterials are often tested in a bath of water or saline heated to 37 °C (body temperature) to replicate a more physiologically accurate environment. While this creates an accurate simulation, using liquid can pose a risk of damaging your Instron system, since many of the frame’s electronics are housed directly under the liquid-filled test space. More often than not, the risk usually comes from filling and emptying the bath.

This risk can be minimized by using the Instron BioCoat: a flexible, polyurethane cover for any single column Instron system (you may remember our post from July). The BioCoat, along with a base plate adapter, creates a water-resistant seal around the base of the machine, greatly minimizing the risk of leaking water or other liquids damaging the electronics within the base of the Instron frame. The flexibility of the BioCoat also allows for easy access to the load and strain cables in the back of the machine.

This video shows how the BioCoat protects the base of the Instron frame. As always, you can contact your local Instron representative for more information. Read more

Question from a Customer: Why is strain rate important?

A. Strain rate is the speed at which a material is deformed and different strain rates can have a big effect on the tensile properties of some materials.
Take silly putty as an example. If you slowly pull on a piece of silly putty, it will stretch an enormous amount before it breaks. But if you pull on it quickly, it breaks almost immediately. This is known as strain-rate sensitivity. Many plastics and polymers and some steels are strain-rate sensitive.
So it’s important to remember that stress/strain data captured at lower strain rates may not produce accurate predictions for the properties of that material at high strain rates. Using that data to analyze and design parts and structures can result in those parts and structures being perfectly able to withstand predicted day-to-day forces. However, when subject to sudden high strain rates such as those found in a collision, those parts and structures could shatter rather than absorb the energy of that collision.

For more information on various materials testing terminology, visit our online glossary. Read more

Reminder: Don't Let Your Standards Slip

You most likely understand the importance of regularly calibrating your testing and measuring equipment and making sure it is maintained to the highest standards to ensure the data that you capture is as accurate as possible. But do you regularly review your testing standards?

ASTM and other standards are continuously improved and amended. Email notification of changes and update subscription services can help you make sure that you stay current. However, it’s important to occasionally review the standards that you work with and examine your test methods and testing practices and procedures against those standards. Particularly for those signing their name to a test report or certification, it's important to question the assumptions and methods used to obtain results and to make sure that you are still fully meeting the standard’s requirements. Read more

Materials in Space

Launched in 1998, the International Space Station is a research laboratory that enables the study of many scientific disciplines under the unique conditions of the space environment. The station is a shared project between five space agencies: the National Aeronautics and Space Administration (USA) (NASA), the Russian Federal Space Agency (Roscosmos), the Japan Aerospace Exploration Agency (JAXA), the European Space agency (ESA), and the Canadian Space Agency (CSA).
Among the many scientific disciplines studied is, of course, materials science.

Space offers scientists a unique environment in which to examine their field of interest. The orbiting space station offers a very low gravity, or microgravity, work domain. Moreover, the rarified atmosphere of the low earth orbit presents unusual conditions that are not encountered on earth.

For the materials scientist, there are two main aims:

• Expose materials and components made on earth to the conditions of the space environment and then test them to identify changes resulting from that exposure.
• Test materials that are formed or processed in space to compare them with the same materials similarly formed or processed on earth.

Material Exposure
The space environment is surprisingly harsh. Atomic oxygen (O1), a free radical, is prevalent in the atmosphere of the low earth orbit and is highly corrosive to many polymers and some metals. Ultraviolet radiation deteriorates many polymers and thin film coatings. The vacuum in space can also alter the properties of many materials and the operation of components. Impacts from dust, meteoroids, solar wind particles, and man-made debris can, of course, damage materials and components.
To investigate the long-term effects of the space environment on materials is the aim of MISSE - the Materials International Space Station Experiment. MISSE evaluates the performance, stability, and long-term survivability of materials and components (switches, mirrors, and so on) for NASA, the Department of Defense (DOD), and commercial companies that have interests in space missions, both in earth’s orbit and beyond.
The materials and components to be tested are packed into Passive Experiment Containers (PECs). These containers, the size of a small suitcase, are secured to rails on the outside of the space station during an astronaut’s extra-vehicular activity (EVA) or space walk. Once installed, the container lid is opened, exposing the various items inside to the space environment. The PECs are left in place for varying periods of time and then removed on a subsequent EVA and returned to earth for testing and evaluation. These experiments help materials scientists develop products, components, and coatings that can meet the requirements of the space environment.

Material Formation and Processing
Many of the industrial processes that produce or process materials involve one or more liquid phases. Materials processes in which a liquid component is present include crystal growth, casting, welding, and atomization. Because these industrial processes involve some liquid component it means that they are also heavily influenced by gravity. Therefore, the International Space Station offers a unique opportunity to study materials in conditions of microgravity. Researchers benefit from studying materials in space because they can isolate the fundamental heat and mass transfer processes involved that are frequently masked by gravity on the ground.
These experiments and processes are carried out in Materials Science Research Racks (MSRRs). Development of the rack was a cooperative effort between NASA and the European Space Agency. Each rack is the size of a large kitchen refrigerator. They let researchers study a variety of materials, including metals, alloys, semiconductors, ceramics, and glasses, to see how the materials form and learn how to control their properties. Each rack is an automated facility with furnace inserts in which sample cartridges are processed to temperatures up to 2,500 degrees Fahrenheit. Once a cartridge is in place, the experiment is run by automatic command or conducted via telemetry commands from the ground. Processed samples are returned to Earth for evaluation and comparison of their properties to samples that have been similarly processed on the ground.

Performing unique experiments and industrial processes in reduced gravity lets researchers obtain a much better understanding of materials development and production with the aim of increasing the accuracy of sought-after material properties such as improved crystal growth, longer and more stable polymer chains, and purer alloys. Read more

Industry Insights Series: Marco Bronzoni

Working alongside our friends at AZOM, they developed a series of engaging interviews with a few of our global colleagues. The first in the series features Marco Bronzoni, Instron Product Manager and Market Manager (CEAST division), where they discuss rheology systems and the importance of thermoplastic testing.

We'd appreciate hearing from you some suggestions for additional interview topics that would benefit your testing and applications. Read more

Simulating a Physiological Environment

In the biomedical world, testing at body temperature and mimicking fatigue felt over time is crucial to ensure the longevity of medical devices. When Director of Medical Devices and Biomaterials Jim Ritchey was at MD&M East, he demonstrated how the BioBox and ElectroPuls help with this need for practical solutions:

 Look for Instron at MD&M West in Anaheim, California from February 12—14 to see other exciting products!

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Hope for the Holidays 2012

 

This past holiday season, Instron (Norwood) had the privilege of supporting 74 children in the community with the help of United Way’s Hope for the Holidays program.

Through donations of clothes, toys, books, and music, we felt great pride in brightening the holidays for others who live and work in the Tri-County area. Here is when the United Way picked up the gifts, making sure the children received the items on their wish lists:

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Tips on Using Environmental Chambers & Furnaces

Does your system incorporate "specimen protect" or "load protect"? If you are not sure, ask us.

If it does you can use this feature to compensate for load string and specimen expansion/contraction while your furnace or chamber reaches set-point temperature.

Having inserted the specimen into the grips, set the desired load threshold value and enable the feature before switching on the furnace or chamber. As the load string expands or contacts, the crosshead or actuator will move to keep the force on the specimen below the threshold value.

• To prevent loss of heat around the pull rods and push rods, always use any convection shields provided or lightly pack the space between the pull rod and the furnace or chamber port with a suitable refractory fiber.
• Make sure you use the recommended anti-seize compounds and lubricants on your grips to help aid specimen removal.
• Use the smallest grips possible to reduce heat-up times and to maximize the available travel in an environmental chamber.
• After you have finished testing at below ambient temperatures, you can remove any condensation from the grips and pull rods by warming them in the chamber and allowing them to cool naturally.

Interested in more tips on tensile testing in high temperatures? Download our complimentary High-Temperature Guide. Read more