In the automotive sector, development in chassis and body of vehicles is driven by two main aspects, safety, and lightweighting. As the body is the first point of impact during a car crash, modern designs have incorporated features such as crumple zone to absorb most of the initial impact, reducing the force that will reach the passengers. With this in mind, it is essential to understand material behavior under high strain rate, especially during development cycles of metals, alloys, and composites that may be used in chassis or body design. On the other hand, lightweighting provides better fuel economy for the car, decreases component wear and hence provide a much more competitive product overall. Therefore, characterizing how material properties change under high strain rate is important in order to find the optimum design maximizing safety and lightweighting.
Chassis and Body High Strain Rate Testing
When considering the crashworthiness of components, testing in high strain rates is essential. As investigated by numerous research, mechanical properties of materials differ drastically under quasi-static conditions and high strain rates. Therefore, accurate data on strain rate dependence of material behavior will provide more realistic computer simulation and evaluation of crashworthiness of structures, whether it is during the development of new alloys or testing automotive components.
To meet the challenges of high strain rate testing, Instron has been the market leader in manufacturing high strain rate testing machines for over 20 years, advancing high strain rate research and testing capabilities on metals with suitable technologies. For testing metals and high-performance alloys, Instron offers a range of VHS systems that can perform tests that will be suited to your application up to a maximum test velocity of 25 m/s, which translates to testing conditions from quasi-static up to a strain rate of 1000/s. Instron also offers fast jaw or slack rod tensile gripping solutions to ensure gripping at test velocity and DIC integration that will provide non-contact strain measurement with the capacity for dedicated strain gauge channels.
Composite High Strain Rate Testing
When conducting material research for lightweighting, composites are good alternatives to conventional materials such as steel and aluminum, as composites, in general, have a high strength to weight ratio. However, due to the nature of the material being more complex structurally, they possess very different mechanical properties when subject to high strain rate. In conjunction with manufacturing limitations in making dog bone specimen, testing of composites under high strain rate is more complex than that of metals and alloys. Therefore, having an accurate and reliable testing machine and a gripping solution is essential in driving composite research in the automotive industry.
For testing composites, Instron provides a range of 8800 High Strain Rate that are suitable for testing composites. Instron also offers fixtures that will be compatible with a composite specimen. Using plasma spray, dowel pin, and pyramid jaw faces, it will provide ample gripping force without inducing surface tear on the composite specimen, in turn preventing failure near grip face. Also, as strain gauges cannot be welded onto composite materials, a high strain rate testing machine with full DIC integration is invaluable in providing a non-contact solution to perform accurate strain measurements.