Operator-split damage-plasticity applied to groove forming in food can lids

This paper presents a numerical–experimental analysis of damage engineering applied to a well-known industrial problem.Many food cans are manually opened by raising a tab on the lid, thus initiating a crack, which is propagated along acircumferential groove. The influence of the groove geometry and depth on the opening force and the resistance againstpremature opening is investigated for some packaging materials, by making use of dedicated experimental techniquesand an operator-split damage-plasticity framework. Attention is focused on a small part of the groove at a location halfwaythe circular crack-path, 900 from the crack initiation point. First, the groovemanufacturing is analyzed by pressing a punchinto a thin sheet of the material. Grooved specimens are loaded in tension, simulating the internal pressure during sterilization,and in shear, simulating the opening. Experiments have been carried out using a miniaturized tensile/compressionstage located in the objective field of an opticalmicroscope. For the computational analysis, an operator-split damage-plasticitymodel is proposed, where ductile damage is easily operated in conjunction with standard plasticity models. Simulationsare done within a geometrically non-linear context, using a hypo-elasto-plastic material model with non-linearhardening and a contact algorithm to simulate the contact bodies in the groove forming process. An arbitrary–Lagrange–Euler (ALE) technique and adaptive remeshing are used to assuremesh quality during the large deformation process.The operator-split procedure used for the solution of the governing equations, allows to make easy use of a non-localdamage operator as an extra feature within a commercial FEMpackage. Experimental results reveal that a reduction up to20% for the opening force with unchanged pre-opening resistance can be reached with the use of an asymmetric punch forthe groove forming. Numerical and experimental results are in good agreement. Simulations show that the industrial processof can lid production can be optimized considerably by controlling damage evolution in the first stage of the process.