Modeling the deformation of fresh porcine bellies: A quantitative comparison of different constitutive formulations

The present work focuses on comparing the ability of different constitutive formulations to model the deformation of fresh pork bellies during handling operations. A computed tomography (CT) scan is initially performed when the belly is lying on a curved substrate, in order to obtain its 3D geometry. Then, based on the assumption of homogenous material behavior, a finite element model is developed and used to simulate the deformation to a flat configuration at which the belly should be trimmed. The simulations are run considering three different constitutive formulations: (i) pure linear elastic, (ii) Ogden hyper-elastic and (iii) hyper-visco-elastic, whose parameters are calibrated by means of uniaxial compression and viscosity tests. The accuracy of each formulation is evaluated by comparing the deformed shape of the belly as predicted by the model to that reconstructed from a CT scan taken with the belly in the flat configuration. Furthermore, the strains inside the belly are estimated with digital volume correlation and compared to the numerical counterpart. It is found that a significant increase in accuracy is achieved by replacing the simple linear elastic formulation with the hyper-elastic one. Conversely, the gain associated with the further transition to a hyper-visco-elastic formulation is less pronounced and might not justify the corresponding increase in computational complexity.