Computational prediction of strain energy release rates of delamination in composite materials

摘要: Delamination is one of the most frequent failure modes composites. Its importance evident since delamination may appear even when there no apparent damage in structure. The residual strength and stiffness delaminated composite decreases significantly consequence that. A study delaminations damaged structure must be made to determine their critical dimensions for propagation via stress intensity factor (SIF), K, or strain energy release rate (SERR), G. Preliminary calculations were carried out isotropic materials. Modes I, II mixed mode situations analyzed. Since three types interfaces crack studied (orientations 0/0, 0/90 90/90), some problems arise determining SIF because its oscillatory behavior. Hence SERR was used this type material, comparing numerical results with experimental DCB (double cantilever beam), ENF (end-notched flexure), ADCB (asymmetric DCB) MMB (mixed-mode bending) test features. calculated inn two different ways: derived from procedure other relies on Rybicki-Kanninen method. All computations performed a commercial FEM code. conclusions were: a) 3D meshes are able predict SIF; b) calculation nearly mesh-independent, contrary c) correlation between data depends stacking sequences d) GII increases more rapidly then GI refinement mesh near tip.