Craze-Yielding Structural Plastics: Toughness Measurement

by Ray D. Hoffman, Assoc. Research Consultant; U.S. Steel Corp., Research Lab., Monroeville, Pa.,

Serial Information: Journal of the Technical Councils of ASCE, 1979, Vol. 105, Issue 2, Pg. 271-279

Document Type: Journal Paper


Efforts are described for obtaining quantitative measures of toughness in structural plastics from single-edge notched tensile tests. Ductile materials such as mild steels and polycarbonate usually respond to loading by through-thickness yielding. In some plastics, however, the transition to through-thickness yielding is inhibited by the development of crazes—thin zones of load-bearing, void containing material. Dugdale-type models have been found adequate to describe the relation between craze length, crack-opening displacement (COD), and applied load for both sharp and blunt-tipped notches. The criterion of failure depends on end use. One definition, crack initiation, has been found not to obey the constant COD criteria, but is very dependent on notch radius. Another, craze zone length at maximum load appears to be independent of notch tip geometry.

Subject Headings: Load factors | Plastics | Toughness | Maximum loads | Thickness | Cracking | Oxygen demand | Tension

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