Analysis of Non-Linear Relationship between Specific Work of Fracture and Ligament of Polymeric Materials Using Modified EWF Model

This paper explores the ligament-dependent behaviour of specific work of fracture of polymeric materials using a recently-developed modified EWF model. It is demonstrated that the non-linear relationship between specific work of fracture (wf) and ligament length (l) is a result of specimen boundary influence on the evolution of plastic zone. A transition ligament (l*) is defined, below which, the height of under-developed plastic zone is equal to the ligament length, and as a result, a linear wf-l relation will be observed. The plastic zone will saturate at the transition ligament, and its height will no longer increase when l > l*. This will result in a non-linear wf-l relation. Experimental wf-l data available in the literature are analysed using the modified EWF model and very good agreements are achieved.

Relationship Between the External Force and the Specific Work of Fracture R for Steady-State Tearing and Peeling of Elastoplastic Materials

A simple relationship is obtained between the external force F and the fracture toughness R for thin sheets in steady state elastoplastic combined tearing and peeling along self-similar paths. The relationship depends only on the material properties (E, σy, and α for an elastoplastic material with linear hardening) and strip cross section (B and H). An earlier analysis (which incorporates transient tearing and peeling) requires lengthy computations over the whole length of the strip. The present analysis avoids that complication. Experiments in steady-state agree with the theory.