The expression of the energetic parameter J proposed by Andrews is re-examined and the influence of finite dimensions is introduced, leading to a general expression of the form J=k(W0).W0.F(aw).a

In this work, fracture tests have been performed on an EPDM based polymer, using two kinds of specimen geometry.

The different terms of this expression are identified using two different approaches:- the first one is based upon a compliance method; - the second one is an energy separation procedure we have developed. Interesting results have been pointed out in this work: - In first, SENT and CCT specimen leads to a similar function k(W₀) which is clearly depending on both the non linear behaviour of the material and of conditions of loading. - Secondly, when considering CCT specimen, the calibration factor F(a/w), derived from the second method, is in good agreement with the Linear Elastic Fracture Mechanics (LEFM) equivalent one. - At least, concerning the deeply cracked specimens, the J estimation using the above mentioned multiplicative form and the direct evaluation from the energy rate dU^*/dA give quite concordant results.