MECHANICAL TESTING

Stress-Relaxation of Plastics - ASTM D 2991

"Standard Practice for Stress-Relaxation of Plastics"
ASTM D 2991 covers the determination of the time-dependence of stress (stress relaxation) of plastics resisting long-duration constant strains at conditions of constant temperature and relative humidity and negligible vibration.

Stress-relaxation test data is useful for predicting the reduction of stress in materials subjected to a constant deformation for a long time, such as the decrease in tightness of a bolted or riveted joint.

This test is highly sensitive to small changes in material composition and environmental conditions and therefore it is useful in evaluating the effect of these changes.

Index of Mechanical Testing