Effects of Strain Rate on the Compressive Stress-Strain Loops of Several Engineering Plastics
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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 <I>l</I>⁄diameter <I>d</I>) of 0.5 are used in the Hopkinson bar tests, and those with <I>l</I>⁄<I>d</I> = 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.
- Proceedings of the Japan Society for Photoelasticity
Proceedings of the Japan Society for Photoelasticity 8, 98-103, 2008-06-25
The Japanese Society for Experimental Mechanics