Dynamic mechanical behaviour of polyethylene

Dynamic compressive curves of high density semi-crystalline polyethylene, PEHD, were obtained via the Split Hopkinson Pressure Bar, SHPB, technique. The SHPB was fitted with polymeric bars, PMMA, to avoid a large impedance mismatch between the specimens and the bars. As a consequence, attenuation and dispersion had to be taken into account. Care was also exercised with frictional effects by using ring specimens instead of flat disks. Ring specimens have the additional advantage of yielding a more constant strain rate in the tests. The results clearly show a very strain rate sensitive material, a feature which should be taken into consideration when analysing PEHD components.