抄録
Compressive stress-strain loops of several commercial engineering plastics at strain rates of up to 600⁄s are determined using the standard split Hopkinson pressure bar. Four different engineering plastics or typical thermoplastics: PA-6, PA-66, PC and POM are tested at room temperature. Cylindrical specimens with a slenderness ratio (= length l⁄diameter d) of 0.5 are used in the Hopkinson bar tests, and those with l⁄d = 1.5 as specified in the ASTM Designation E9-89a are used in the static tests. The stress-strain loops in compression at low and intermediate strain rates are measured on an Instron testing machine. The effects of strain rate on the Young's modulus, flow stress at 2.5% strain and dissipation energy are investigated. It is demonstrated that the area included within the stress-strain loop (or dissipation energy) increases with increasing strain rate as well as given strain, that is, all plastics tested exhibit intrinsic strain-rate dependent viscoelastic behavior and a high elastic aftereffect following complete unloading.
