Assessment of Techniques Used to Measure Strain During High Rate Tensile Testing of Polymeric Materials 2008-01-1338
Recently the University of Dayton Research Institute (UDRI), the Society of Automotive Engineers (SAE), and the High Strain Rate Plastics Committee (HSRPC), participated in a cooperative research effort to develop and assess the precision statistics of a Practice Guide for High Strain Rate Testing of Polymers. Development of the practice guide included collaborative research, surveys and an interlaboratory test program. This practice guide was incorporated into the draft SAE-J Standard (SAE J2749 High Strain Rate Tensile Testing of Polymers) and will be approved as a standard in 2008. SAE-J2749 addresses instrumentation and data analysis issues associated with measuring load. Information regarding strain measurement methods during high strain rate testing of polymers was obtained through the interlaboratory test program. This paper will describe various commercial techniques used to measure strain during high rate testing, such as non-contact electro-optical extensometer (various lens sizes), laser vibrometer, laser-doppler extensometry, high speed video, and strain gauges. The advantages and disadvantages of the techniques will be discussed. Additional information obtained from a survey of testing facilities will be presented and discussed.