Simulation of the behavior of the calfskin used as shoe upper material in footwear CAD

The aim of this work is to propound a mechanical behavior model for simulating the deformation of the shoe upper material in gait for footwear CAD applications. The chosen material is calfskin. The proposed material behavior for the working range is a linear elastic orthotropic model which considers large deformation and membrane and bending loading. The model was obtained from tensile tests and validated with two experiments: a test to measure the leather resistance to damage on lasting and a test that models the shoe forming process using lasts. The framework of this work is the simulation of the footwear deformation while walking for footwear computer-aided design, and these tests have been chosen because, in them, the shoe upper material is deformed in a similar way to those deformations that occur during a complete step. The tests have been simulated using the Finite Element Method. The results of this simulation show that, in most of the cases, the orthotropic model closely represents the real behavior of the leathers analyzed in this work.