ECCM 2010 IV European Conference on Computational Mechanics Palais des Congrès, Paris, France, May 16-21, 2010 Shell Interface Finite Elements for the Simulation of Folding and Cut- ting of Composite Laminates U. Perego 1 , A. Frangi 1 , A. Giampieri 1 , M. Pagani 1 1 Department of Structural Engineering, Politecnico di Milano, Italy umberto.perego@polimi.it; attilio.frangi@polimi.it; giampieri@stru.polimi.it; pagani@stru.polimi.it Carton packaging is one of the key ingredients for the distribution of goods from production to the final destination and it is a fast growing industry. Depending on the particular type of packaging required, the production of carton packages can be a rather complex process. The need for waste reduction and increasing competition are encouraging the development of computational tools for the simulation of the production and opening processes and for its optimization. Two different aspects concerning the finite element simulation of the forming and opening processes of carton packages are considered in the present work: the folding of the paperboard around pre-scored crease lines for its conversion from the initial flat configuration to the final box shape; the cutting of the package laminate by means of a screw driven cap, connected to high density polyethylene teeth. To facilitate the folding of the paperboard around the prescribed lines, before being converted into its final shape, the paperboard blank is “creased”, i.e. the folding lines are scored onto the paperboard by pressing it by a male die with a rule onto a grooved female die (see Figure 1). The creasing produces a local, shear induced delamination into the paperboard structure which reduces its bending stiffness and promotes the folding around the design lines. In the present work an interface finite element for the simulation of the crease presence in a curved laminate, is presented. The element is designed to be placed between adjacent 4 node shell finite elements of the Mindlin-Reissner type. The element is formulated in terms of generalized internal forces (moments and tractions) and relative displacements (displacement jumps at the shell midsurface and relative rotations). The material model accounts for the permanent elastoplastic deformation of paper and both for the initial and progressive delamination damage due to the creasing and subsequent folding of the paperboard. Particular attention has been devoted to the definition of the dependency of material parameters on the crease penetration depth (parameter γ in Figure 1). The model has been calibrated on the experimental results provided in [1] showing good agreement, as can be appreciated in Figure 1. Figure 1: Creasing process and bending moment-rotation crease response for varying penetration depth. 1