Explicit dynamics simulation of blade cutting of thin elastoplastic shells using “directional” cohesive elements in solid-shell finite element models

Finite Element Simulation of Crack Propagation and Delamination in Layered Shells Due to Blade Cutting

“…in correspondence of the middle surface in the thickness direction) in view of the assumed small thickness, while along θ different choices are considered, as summarized in table 1. The implementation used in [6,12] connects the DCEs to the fiber nodes at the crack flanks. This can be interpreted as adopting a NCI with a trapezoidal rule.…”

“…At the insertion of the DCE, the nodes of the opening flanks are duplicated but they are still geometrically coincident. In the original implementation of the directional cohesive elements [12], the cohesive strength was initialized to match the component of the Cauchy stress normal to the crack flank at the integration point, consistent with the assumed mode I dominated opening. However, this procedure in general does not respect the force balance at the node.…”

“…The blade can interfere with the correct transmission of the cohesive forces, leading to severe underestimation of the dissipated energy. A possible remedy to this inconvenience has been proposed in [6,12], with the introduction of the so called directional cohesive elements (DCEs). When a crack propagation criterion is met at a node, the node is duplicated and cohesive string elements are attached to the opening faces.…”

Efficient and accurate simulation of the packaging forming process

“…Key features in the element formulation includes methods to relieve element locking, ie, the enhanced assumed strain (EAS) method and the assumed natural strain (ANS) method, together with a Taylor expansion of the stress state along the thickness direction in order to improve accuracy for shell problems. Only one EAS degree of freedom is needed in the element formulation, which, together with reduced in‐plane integration, results in a computationally efficient element formulation suitable for explicit dynamics simulations as demonstrated in Pagani et al The solid‐shell element has been previously used together with cohesive elements in Pagani and Perego to model the industrial application of dynamic blade cutting with promising results. In Vladmirov et al and Schwarze et al, forming of sheet metal was modelled with the solid‐shell element using both isotropic and anisotropic constitutive laws together with finite strain plasticity.…”

Simulation of Fracture and Delamination in Layered Shells Due to Blade Cutting

“…The adopted computational strategy for the simulation of cutting, based on the use of "directional cohesive elements", has been described in (Pagani et al, 2015). This work will rather focus on the modelling of the delamination problem.…”