Question

In stress strain curve where extension occurs with little resistance

Answer 1

 The paper is concerned with the problem of crack extension in materials such as rubber, animal membranes or human membranes, where the stress-strain curve is J shaped, i.e. there is a low resistance to tensile deformation initially, followed by a considerably greater resistance before failure. Analysis of a very simple simulation model, which takes due account of the discreteness of the material's structure, shows that the work of fracture or effective fracture energy γeff can be large and can be considerably greater than the value which is obtained by regarding it as the area under the force law curve, as would be the case if the material is regarded as a continuum. The theoretical predictions accord with experimental observations that γeff is large for a material with a J-shaped stress-strain curve.