STRESS DISTRIBUTION IN CRAZE REGION USING CAUSTIC TECHNIQUE IN POLYMERIC MATERIALS

Abstract

The fracture of polymeric material in the presence of liquid environment always proceeded by craze region due to stress concentration in this area. Study of stress state in this region is of a prim important for understanding failure mechanism of polymers, The present work aim to study the stress• distribution in craze region. •Experiments were carried out on PMMA and PC with SEN spec1mens. Methanol, ethanol, butanol and kerosene were used as a crazing agent. The specimens stressed under tension at specific stress calculated by LFM. The shadow optical method (caustic) was found to be a suitable method for stress analysis at stress concentrated areas and was used to detect stress state at crack craze tips. The stress at crack and craze tip was evaluated. It may be concluded that the stress reduce with increasing craze length at different environments and loading conditions at both crack and craze tip. The stress field along PMMA and PC craze is not uniform but has the maximum at crack tip for all environments except for PMMA methanol.