Abstract: : In this paper, the formula of conservative integral with the relationship between J1 -integral and the stress intensity factor (SIF)KⅡ in two dissimilar media is derived by using the principle of virtual-work. For the delamination of composite laminate beam stacked orthogonally and symmetrically with four plies under transverse loading, the magnitudes of J1 -integral along different paths are obtained on the basis of the determination of the SIF and all of the coefficients in the expansions. According to the relationship between J1-integral and SIF,KⅡ, can also be determined and compared with those determined by generalized-variational principle. The computational results show that this method has the advantages of simple preparation, rapid convergency and time-saving, the magnitudes of J1- integral along different paths keep constant accurately and the SIFs obtained by direct variational method and by indirect J1-integral method agree with each other satisfactorily.

Key words: delamination, laminate beam, stress intensity factor, conservative integral analytical-generalized variational method