Special Concerns in High Strain Rate Tensile Testing of Polymers

Recently the University of Dayton Research Institute (UDRI), the Society of Automotive Engineers (SAE), and the High Strain Rate Plastics Committee (HSRPC), conducted an interlaboratory test program (ITP) to assess the precision of the Practice Guide for High Strain Rate Testing of Polymers. In addition to generating precision statistics, the intent of this ITP was to develop the Practice Guide to a level of maturity where it could be released as an SAE-J Standard in 2005. The ITP was conducted at 12 laboratories using five polymers: high density polyethylene (HDPE, Dow Chemical Co.); polycarbonate/acrylonitrile-butadiene styrene terpolymer (PC/ABS, LG Chem, Ltd.); thermoplastic elastomer-olefinic (TPO, Solvay Engineered Polymers); long glass (11 mm) fiber 40% filled polypropylene (GF PP, LNP Engineering Plastics); and short glass (2-3mm) fiber 30% filled polyamide 66 (GF PA, Bayer Polymers LLC) and two nominal plastic strain rates, 40/s and 400/s. Information generated from the ITP testing identified several special concerns associated with high strain rate testing that were not obvious from the data provided by the individual laboratories or through the statistical analysis used to generate the precision statistics for the Practice Guide. This paper will discuss one of these concerns and present the effects that modifying the ITP data set had on the precision statistics.