Efficient modelling of dynamic delamination growth with arbitrarily shaped fronts using large and distorted elements
Topic(s) : Material and Structural Behavior - Simulation & Testing
Co-authors :
Pierre M. DANIEL (SPAIN), Johannes FRÄMBY (SWEDEN), Martin FAGERSTRÖM (SWEDEN), Pere MAIMI (SPAIN)Abstract :
Out-of-plane failure is common in composite layered materials. Its detection and modelling in finite element simulations usually involves a high level of spatial resolution through the thickness of the laminate, which may lead to an excessive computational time for large structures. Furthermore, if traditional cohesive zone elements are used to model the propagating delaminations, also the in-plane element size is limited (typically to < 1mm) by the quasi-brittle nature of delamination failure [1]. All combined this leads to a need for very dense discretisations, leading to long to unfeasible computational times.
In this contribution, we present a computational method that promotes computational efficient delamination modelling, by combining a general formulation for accurate recovery of the through-thickness variation of transverse stresses [2], with an adaptive shell modelling approach that allows new delaminations to form as displacement discontinuities adaptively introduced as the simulation progresses [3]. Furthermore, to enable the use of comparatively larger in-plane dimensions of the shell elements, we adopt an energy release rate-based cohesive method [4,5] that allows predictive modelling of delamination using in-plane element sizes significantly larger than the damage process zone.
As for the recovery of transverse stresses, the proposed formulation [2] has the advantage of being applicable to arbitrary laminates, curvatures and load conditions. The numerical results confirm the potential of the proposed method to be used both as post-processing tool for conventional models and as an enrichment criterion for the adaptive modelling.
Furthermore, the adaptive crack propagation [3] is determined with an estimation of the energy release rate by means of the virtual crack closure technique. To progressively open newly formed crack segments along the element surface, a novel nodal cohesive law is introduced. This cohesive formulation allows to smoothly release the interface, while dissipating the appropriate amount of energy, also under mixed mode conditions. Numerical results show the capability to accurately simulate double cantilever beam, end-notched flexure and mixed-mode bending tests with regular and irregular meshes for element lengths up to 8 mm [4]. Recently, this method has also been extended to handle the case of in-plane irregular meshes [5], including having the capability to capture an evolving shape of the delamination front.
In this contribution, we present a computational method that promotes computational efficient delamination modelling, by combining a general formulation for accurate recovery of the through-thickness variation of transverse stresses [2], with an adaptive shell modelling approach that allows new delaminations to form as displacement discontinuities adaptively introduced as the simulation progresses [3]. Furthermore, to enable the use of comparatively larger in-plane dimensions of the shell elements, we adopt an energy release rate-based cohesive method [4,5] that allows predictive modelling of delamination using in-plane element sizes significantly larger than the damage process zone.
As for the recovery of transverse stresses, the proposed formulation [2] has the advantage of being applicable to arbitrary laminates, curvatures and load conditions. The numerical results confirm the potential of the proposed method to be used both as post-processing tool for conventional models and as an enrichment criterion for the adaptive modelling.
Furthermore, the adaptive crack propagation [3] is determined with an estimation of the energy release rate by means of the virtual crack closure technique. To progressively open newly formed crack segments along the element surface, a novel nodal cohesive law is introduced. This cohesive formulation allows to smoothly release the interface, while dissipating the appropriate amount of energy, also under mixed mode conditions. Numerical results show the capability to accurately simulate double cantilever beam, end-notched flexure and mixed-mode bending tests with regular and irregular meshes for element lengths up to 8 mm [4]. Recently, this method has also been extended to handle the case of in-plane irregular meshes [5], including having the capability to capture an evolving shape of the delamination front.