THE ENERGY-RELEASE RATE OF NONLINEAR DOUBLE CANTILEVER BEAM SPECIMENS

The paper deals with the energy release rate G of nonlinear double can tilever beam (DCB) specimens. Often the equivalence of the basic defin ition G = -(1/B)partial derivative W/partial derivative l (B: width of the specimen, H: Helmholtz energy, l: crack length) and the expressio n G = (1/B)partial derivative W/partial derivative l(W: elastic energ y) is assumed. The validity of this assumption is investigated. It is concluded that for the nonlinear DCB specimen the two expressions are not equivalent so that the basic definition for G should be used. The paper further comments upon an article [1] in which nonetheless C is used for the nonlinear DCB specimen and, contrary to expectation, good agreement with experimental data is obtained. The reason for this agr eement is indicated.