METHOD FOR DETERMINATION OF ULTIMATE STRESS OF CELLULAR RIGID PLASTICS AT TENSION

摘要

A method for the determination of ultimate stress of cellular rigid plastics at tension includes application of tension force to samples. At the middle of the working parts of rectangular samples at angle 90° to the facets of those and at the middle of the working section of the cylindrical sample at its perimeter as tension concentrator an acute cut with depth 0.5 mm and with angle at the top 45° is provided. The evaluation of sensitivity of plastic to the cut is determined by effective stress concentration factor, this is calculated by the ratio of the value of ultimate stressof the cut sample to the value of the ultimate stresswith same net cross section by formula:.