THE PLANE-STRAIN ESSENTIAL WORK OF FRACTURE AS A MEASURE OF THE FRACTURE-TOUGHNESS OF DUCTILE POLYMERS

We have extended the essential work of fracture technique to allow for the determination of the plane‐strain essential work of fracture. The new technique is to measure the specific work of fracture as a function of ligament length in deeply double edge notched samples. This type of data is then experimentally corrected to remove the plastic work of fracture and leave only the essential work of fracture as a function of ligament length. By extrapolating the essential work of fracture to zero‐ligament length, we claim to be measuring the plane‐strain essential work of fracture. This new technique was applied to two rubber toughened nylons and to a series of polyethylenes. The plane‐strain essential work of fracture was found to be independent of thickness. Where comparison can be made to J‐integral testing, the plane‐strain essential work of fracture was similar to the critical J‐integral, JIc. Copyright © 1990 Society of Plastics Engineers