1994-03-01

High Strain-Rate Characterization of Thermoplastics Used for Energy Management Applications 940882

An interesting characteristic of virtually all materials is their strain-rate sensitivity. In the case of engineering thermoplastics, these materials exhibit ductility and very good impact resistance at low to average strain rates (<10 %/sec) but can become extremely brittle and unforgiving at high strain rates (100 - 5.000++%/sec). This becomes a concern in energy management applications, such as automotive instrument panels and knee bolsters, because, for example, the average head impact on an instrument panel induces a 1,000%/sec strain rate.
Engineering analysis of the impact event typically under-predicts loads and over-predicts deflections. Making material substitutions within a design may be of little use since the newcandidate may be more strain-rate sensitive than the original polymer. Many of the most widely specified engineering thermoplastics behave very differently in standardized ASTM “static” tests than in high strain-rate situations. Therefore, it is difficult, if not impossible, to accurately estimate performance based on extrapolated low-strain data.
Responding to a need for accurate data measured at high strain rates, and recognizing that very few organizations are equipped to perform such testing, GE Plastics and Davidson Instrument Panel have initiated a research program with the University of Dayton Research Institute (UDRI) to characterize the strain-rate sensitivity of common grades of polycarbonate (PC), acrylonitrile butadiene styrene (ABS), polycarbonate/acrylonitrile butadiene styrene (PC/ABS), polybutylene terephthalate (PBT), polycarbonate/polybutylene terephthalate (PC/PBT), and modified-polyphenylene ether (M-PPE) resins.
This paper will disclose the results of the high strain-rate material testing (up to 5.000 %/sec) and resultant performance of these materials. Discussion will center around how engineers can use these data to better predict material behavior in complex assemblies.

SAE MOBILUS

Subscribers can view annotate, and download all of SAE's content. Learn More »

Access SAE MOBILUS »

Members save up to 43% off list price.
Login to see discount.
Special Offer: With TechSelect, you decide what SAE Technical Papers you need, when you need them, and how much you want to pay.
X