How Much Action Can Hip Protectors Take on the Field Hockey Turf?

We love field hockey here at Instron and are looking forward to catching some of the action as it unfolds during the London Olympics 2012. Field hockey is an exhilarating game that demands speed, stamina, and excellent hand-eye co-ordination from its players in order to succeed.

Unfortunately, field hockey also presents numerous opportunities for injuries due to the fast-paced, repetitive actions of the sport (not to mention the use of the hard stick and ball!). A high proportion of these injuries can be prevented by ensuring the correct protective equipment, such as hip protectors, are worn.

At Instron, we use our CEAST 9350 Impact Testing System to test the impact resistance of protective items such as the hip protectors worn during hockey. The evaluation of the performance of the protector is conducted by simulating a fall on the impact test system. The test configurations of these systems can then be specifically designed in order to accurately reflect the pressures placed upon the protector during different falls and test their suitability for use—clever!

Read our recommended testing solutions for impact resistance of hip protectors using our CEAST 9350 testing system. Read more

Testing Arrows for Pinpoint Accuracy in Archery

The London 2012 Olympic Games have provided a lot of excitement for archery fans. South Korea's Im Dong-hyun, legally blind in one eye, set the first Olympic World Record. The South Korea Women's Archery Team won gold as did the Italian Men's Team.

Olympic archers aim their arrows at targets measuring from 122 cm to 12.2 cm in diameter from a distance of 70 m. They must have a keen eye, backed by nerves of steel, to hit the target.

Today, most Olympic archers use arrows made up of composite materials. Instron performed impact tests on the shafts these composite arrows to see how their properties would measure up. An impact resistance test performed on a CEAST 9310 falling weight system coupled with a 3-point bend test provided the data that determined the benefits of the composite shaft. The  properties of the composite materials allow the shafts to be made thinner and lighter, thus increasing the arrow’s speed. The durability also prevents splitting upon impact, allowing for a more secure hit on the target.

Even archer bows are made of composite material nowadays. In fact, the “recurve bow”, which is the standard bow used in the Olympics, is primarily made of either carbon fiber or fiberglass. Again, in this application, the strength and durability of composite materials, coupled with the light weight attributes, play important roles.



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The Art of Crushing Concrete (or the Competition)

Today, the world is meeting on a global stage in London; immense planning has gone into these Games long before the Olympians and the spectators arrived.

Sustainability and re-use were major themes in developing the structures for the Olympic venues. A 35-ton recycling machine was installed to crush and separate debris and contaminants from the sites. The machine was able to separate up to 500 tons of concrete, soil, metals, and glass each day. Once materials were separated, they were "cleaned" and evaluated for re-use within the Olympic sites.

Accurate and controlled compression is an art and a science. Instron’s testing solution on compression testing of cylindrical concrete specimens provides perspective on crushing concrete in compliance with ASTM C39, the industry standard for more than 80 years. Read more

Instron and the Olympics

Throughout the Olympic Games, strength and endurance is tested in elite athletes. A parallel comparison can be made when ensuring the quality of the equipment used to facilitate this global competition. For the next several weeks, Instron will be sharing how testing systems are able to provide confidence to the supplier and ultimately, the end-user. Check back frequently to see the latest testing solution supporting quality behind the Olympics.

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Niagara Prosthetic Foot: Material and Structure Working Together

According to the International Campaign to Ban Landmines, landmines threaten adults and children in at least 72 countries. Millions of landmines of various types remain hidden around the world, waiting to be triggered by the innocent. The ICBL publication Landmine Monitor 2011 estimates that over 4,000 casualties occur each year from landmine explosions, many of them resulting in the loss of limbs.

In 1998, the landmine situation around the world was even worse and landmine casualties numbered in the tens of thousands. These awful statistics prompted prosthetist Rob Gabourie of Niagara Prosthetics and Orthotics International Ltd., to design and develop a flexible, durable, and inexpensive prosthetic foot as part of the landmine victims relief program of the Canadian Centre for Mine Action Technology (CCMAT).

The Niagara Foot is a simple and elegant design, but the biomechanics are complex. The foot is formed as a single part, with a heel area, a toe area, and a strong dynamic C-section at the ankle. Each of these act as springs providing elastic energy storage and return during the gait cycle. The properties of the material partnered with the unique structure let the foot mimic biological foot action. Moreover, its comparative low cost means it is potentially accessible to many more people. However, it has taken several years of research and testing for the foot to achieve this performance.

In 1998, at the start of the project, Mr. Gabourie invited Dr. Tim Bryant of the Human Mobility Research Centre in Queen’s University (Ontario) to collaborate on the design and help with the biomechanical testing and material analysis. DuPont, the science company, also became involved in the project to help determine what kind of material should be used to make the foot. The designers tested various materials before selecting the DuPont™ Hytrel® advanced polymer.

Testing for material characterization, biomechanical evaluations, and overall durability has factored strongly into the development of the foot. Much of the materials characterization testing was performed using Instron® static and dynamic testers at DuPont research laboratories.

Static testing on the foot structure was performed at Queen’s University using an Instron testing system. Forces were applied to the toe and the heel of a foot, and held for a period of time. The goal is to ensure that the structure can meet or exceed standard values that represent high loading conditions, such as jumping, as set by standards such as ISO 10328 (Prosthetics — Structural testing of lower-limb prostheses) and ISO 22675 (Prosthetics — Testing of ankle-foot devices and foot units).

Cyclic durability testing was undertaken using a pneumatic fatigue tester designed and built at Queen’s University. It comprises four stations, each with a pneumatic loading cylinder for the heel and toe. Cylinder actions are computer-controlled to produce an axial force waveform similar in shape to that observed in a normal gait. At the same time, the peak force values at the heel and toe are programmed to be consistent with those required in the ISO standards. More than 3 million cycles did not result in failures or significant wear. The combination of the simple shape and effective material selection has resulted in a foot prosthetic that is more durable.

The Niagara Foot has gone through field-testing in Thailand and El Salvador that followed disciplined protocols.

A major benefit of the Niagara Foot lies in its ability to be locally customized to the needs of the owner, each with varying weights, heights, and activity levels. Local modification is accomplished with the prosthetist using a simple hand file to reduce the thickness of the heel, toe, and C-section and adjust their profiles using guidelines that accompany the foot. This ability to easily adjust the foot to tune its performance is unique among existing prosthetic feet and makes it ideal for use in developing countries.

The Niagara Foot was commercially released recently as the Rhythm Foot (http://www.rhythmfoot.ca/). Earlier this year, the foot won the gold award in the rehabilitation and assistive-technology products category in the 2012 Medical Design Excellence Awards in Philadelphia.

Professor Bryant is quick to emphasize the collaborative nature of the development process. The involvement of several major companies, universities, and organizations from different countries was an underlying factor for the Niagara Foot won the MDEA award, Bryant shared. Some of the organizations included Niagara Prosthetics & Orthotics International Ltd., DuPont Engineering Polymers, Centennial Plastic Mfg. Inc., and Universidad Don Bosco in El Salvador.

DuPont™ and Hytrel® are trademarks or registered trademarks of E. I. du Pont de Nemours and Company. DuPont Canada is a licensee.

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Question From a Customer

Q. What is the best way to grip soft biological tissues for tension testing?

A. The most common challenges associated with tensile testing of soft biological tissues are specimen slippage and breaks near the jaw faces. For most delicate soft tissues, use pneumatic grips with either SurfAlloy® faces or smooth faces with low grit sandpaper. One of the key features of the pneumatic grips is the adjustable gripping pressure. Gripping force can be reduced to minimize jaw breaks or gripping force can be increased it if specimen slippage occurs. The SurfAlloy® faces or the use of sandpaper with smooth faces increase the surface friction between the specimen and the jaw faces, thereby reducing slippage. For other needs, Instron has a wide variety of jaw faces available to customize to various circumstances. Read more

Data Rate and Bandwidth

Performing tests with the appropriate data rate and bandwidth is critical in obtaining accurate and meaningful data.

The data acquisition rate of a computer or data acquisition system is the speed at which raw data points are captured. The rate should be based on the speed at which the incoming signal is changing. If the incoming signal is not changing quickly, then high data rates lead to excessive data being captured with large files and wasted disk space.

The following variables should be considered in the data rate discussion:

1. Actual signal being measured
2. Bandwidth of the signal conditioner (filtering)
3. Data acquisition rate

Actual Signal

One of the most critical aspects of proper measurement is to understand the rate at which things occur during a test. For example, when testing composites, the signal contains short, sharp peaks (or signals) indicating that the data is changing quickly, whereas tensile tests on plastics typically do not show high frequency changes.

 

Bandwidth

In order to properly capture these actual events, signal conditioning with the correct frequency bandwidth needs to be calculated.

Bandwidth can be loosely defined as the frequency above which signal changes are not measured; those changes are filtered out and flattened. For example, it is not possible to measure 100 Hz peaks with a 10 Hz signal conditioner; the peaks will be invisible.

 

Data Acquisition Rate

The ideal data acquisition rate is a function of the signal conditioning bandwidth, which should be matched to the rate of change of the actual event. A rule of thumb is that a data rate more than 10 times the signal conditioning unit bandwidth produces little more than wasted disk space, because the same data is being sampled over and over.

For a complete review of data rate, signal conditioning, noise filtering and how they affect mechanical testing results, consult ASTM Standard Guide E 1942. Read more

Don't Forget Your BioCoat

When testing catheters, stents, and suture materials, simulating the environment in which they will be used provides for more true-to-form testing. For this reason, many medical devices and biomaterials are tested in a bath of water or saline heated to 37 °C, or body temperature, to accurately replicate a biomedical environment. But when using a bath with testing, there is a risk of it spilling or leaking onto the instrument, especially if the bath is being used, filled or emptied incorrectly; and we all know, electronics and liquids should not mix. Liquids can damage the testing instrument as well as become a hazard to the operator. To alleviate this issue, Instron developed the BioCoat — a waterproof, polyurethane cover that slips over any new or existing 594x single column frame. The BioCoat serves as a flexible shield that protects the frame from liquids, while still allowing easy access to all connectors and controls.

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Get Informed before Your Next Calibration

To first summarize this weeks posts, calibration is the physical process of taking comparative measurements from your device against a standard device, and verification is the analytical process of comparing the resulting measurement errors against the performance specification of your device. Verification is, of course, not possible without the preceding calibration. However, verification is so closely related to calibration that they are treated as two inseparable parts of the same process.

We don't want the next catastrophic headline to bring your company into sharp focus, as it can happen any time. So make sure you know the importance of, and the difference between, calibration and verification, and that your calibration records are ready for scrutiny at all times.

So we can help you prepare for your next calibration, below are some valuable resources.....

• Questions to Ask Your Calibration Provider
• More information on Calibration and Verification Services
• Calibration FAQs

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Calibration vs. Verification

What is Calibration?

Calibration is simply the process of comparing an unknown value to a known value. To calibrate a device is to compare the output of that device with the output of a similar but highly accurate device called a “standard”. Using load cells as an example, the load cell being calibrated (the unknown) and the standard load cell (the known) are mounted and a range of loads is applied. Because they are in series, both load cells experience identical loads and therefore the output values should also be identical. The calibration result is the difference between the two values, otherwise known as the measurement error.

What is Verification?

Verification is the subsequent evaluation of the calibration result against the expected performance specification for the equipment. The performance specification dictates the limits of the measurement errors for the device under test. If the measurement errors throughout the range are less than the specified limits, the device is verified as conforming to its performance specification. If the errors are greater than the specified limits, the device is verified as not conforming to its performance specification. Note that in either case, conforming or not conforming, the equipment is still considered to be verified.

What's a common misconception?

A common misconception is that calibration means adjusting the output of a device to bring its performance “within limits.” Any adjustment made to the output of the device is separate from the calibration and verification process, and must be followed by a further calibration and verification to prove the adjustment was successful.

Learn more about Calibration vs. Verification.

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Are You Always "Investigation Ready?"

An overweight aircraft crashes, a bridge fails, a building collapses. Accidents occur as the end product of a chain of events; a series of small failures, each one linked to the next. Prevent any one of them, and you break the chain; the accident cannot occur.

After every major accident, investigators examine every link in that chain of events. These investigations are detailed and comprehensive; they will include manufacturer's calibration records for testing instruments used in the production of materials and structures. Public reports of poor calibration management and record keeping, whether contributing to the accident or not, promote doubt and distrust among your customers about your quality standards.

It's clear that the more you know about how testing equipment is calibrated and verified the better prepared you are to effectively assess a calibration service's qualifications and capabilities. However, even the basic terms calibration and verification are confusing to many people.

So what is the difference between calibration and verification? You can leave your comments below or stay tuned for Instron's answer tomorrow.... Read more

Can't Handle the Contact???

Do you have a specimen that is too delicate for a contacting extensometer? Don’t fret! Check out this solution for testing a single fiberglass fiber using Instron’s Advanced Video Extensometer (AVE):

The shown fiber is being tested for mechanical strength and modulus, which are important to understand the effectiveness of the end product where this fiber will be used. As one can imagine, with the fiber being only microns in diameter, a contacting extensometer would definitely not work for this application. Therefore, two marks were placed on the epoxy that is holding the fiber to the paper panes and those marks were tracked throughout the test with the AVE.

This single fiber will eventually get wound with hundreds, sometimes thousands, of identical fibers which ultimately are weaved into a final product. Fiberglass products can be found in the automotive, aerospace, boating, and even construction industries. With fiberglass being as popular as it is, one can understand the importance of accurately identifying its mechanical properties (even down to the single fiber stage!).

This is just one unique way of using an extensometer on a specimen that normally wouldn’t call for an extensometer to be used. There are many instances where a unique solution can help, and this is just one example! Please leave a comment if you have any questions/concerns about your testing. 

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