PLASTIC STRAIN CONCENTRATION BY MEANS OF PHOTOPLASTICITY AT A CIRCULAR HOLE EDGE IN A FINITE SHEET SUBJECTED TO UNIAXIAL TENSION

High molecular materials are generally used for many important structural members of machines, in spite of the present circumstances where the ductile fracture characteristics are not sufficiently known. The present study has been directed to determine the plastic strain concentration factor at the edge of a round-hole under the uniaxial stress field. Plastic strain concentration factors at the edge of a round-hole notch were measured by photoelastic stress analysis technique under defferent tension rates. Concentration factors were calculated from results obtained, and the experimental result was compared with the theoretical values. Faily good agreement was found between them.