“On the use of the essential work of fracture procedure in the determination of the fracture energy of tough polymeric materials”

The determination of the energy of fracture of tough polymeric materials in plane strain conditions by means of the essential work of fracture procedure has nowadays two open questions. The first is related to the ligament length that has to be used when the impact specimens break partially upon testing, and the second is related to the way to assure that the crack propagation occurs in an already yielded zone. The use of i) a “true ligament length” associated with only the broken area and ii) impact specimens yielded in the notch zone in a previous tensile test, are evaluated and proposed.