抄録
The present work is concerned with the determination of stress-strain hysteresis loops of several polymers in compression at strain rates of nearly 700/s using the standard split Hopkinson pressure bar. Four polymers or typical thermoplastics: ABS, PA-6, PA-66 and PC are tested. Cylindrical specimens of slenderness ratio (= height/diameter) of 0.5 are used in the Hopkinson bar tests, and those of slenderness ratio of 1.5 as specified in the ASTM Standards are used in the static tests. The low strain-rate stress-strain hysteresis loops in compression are measured in an Instron testing machine. The effects of strain rate on Young's modulus, 2.5% flow stress and dissipation energy (energy loss due to damping) are examined. It is demonstrated that the area within the stress-strain hysteresis loop (or dissipation energy) increases with increasing strain rate, that is, all polymers tested exhibit intrinsic dynamic viscoelasticity and a high elastic aftereffect following unloading.
