Application of the virtual crack closure technique to calculate stress intensity factors foe through cracks with an elliptical crack front

摘要

Fractographic observations on fatigue tested 2024-T3 clad aluminum riveted lap-splice joints indicate oblique fronts after the initial surface or corner crack at a rivet hole has penetrated through the sheet thickness. No stress intensity factorsolutions. K s, are available for this geometry subject to remote tension, remote bending and rivet loading, which are typical for a pressurized fuselage of a transport aircraft. To reduce model generation time for each crack geometry. one finite elementmesh is modified to create a new mesh for each crack geometry; thus, maintaining an orthogonal crack-front mesh is not possible. The validity of the three-dimensional virtual crack closure technique, 3D VCCT, with nonorthogonal finite element meshes forcalculating mode I stress intensity factors is assessed. Comparisons are made to existing two- and three-dimensional K solutions obtained using conformal mapping. boundary collocation and finite element analysis. Parametric investigations on the influence of rivet load distribution revealed different effects on K for small and large cracks. Using the 3D VCCT with a nonorthogonal mesh, a cursory sensitivity study is accomplished to assess the effect of the crack shape of a through crack on the K.