Welcome to our new Instron Community Blog hosted by Instron. It is a compilation of the freshest, brightest, most-talented minds that Instron has to offer. The world of materials science is so vast and encompasses the broadest range of industries, materials, and challenges that no one person can possibly possess all the knowledge required to be the resident expert – or master of materials science. It takes a small army behind the scenes collaborating and sharing technical know-how, experiences, and ideas to present the most accurate, relevant, and timely information to you – our readers.

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Monday, October 28, 2013

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.
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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.
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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.
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Thursday, October 17, 2013

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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Friday, October 11, 2013

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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Tuesday, October 8, 2013

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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