Finite element meshes for optimal modelling of plasticity induced crack closure

• An expression was proposed for the size of refined mesh along propagation direction.
• The mesh refinement produces an asymptotic increase of maximum plastic strain.
• An optimum value exists for the size of crack tip elements.
• The numerical model should be calibrated using experimental results.

The main goal here is to optimise the finite element mesh used to predict plasticity induced crack closure (PICC). A numerical model was developed for a M(T) specimen made of 6016-T4 aluminium alloy. The parameters studied were the size of most refined region perpendicularly to crack flank (ym) and along propagation direction (xr), the size of finite elements near crack tip (L1) and the vertical size of refinement close to crack flank (yA/B). A maximum size of about 1.3 mm was found for ym, but a smaller value has a limited impact on PICC. An analytical expression was proposed for xr, dependent on ΔK and Kmax. An optimum value seems to exist for L1.