Finite element simulation of the biaxial stretching process and mechanical properties of TPU films

In this paper, we present experimental and finite element simulations for optimizing the biaxial stretching of thermoplastic polyurethane (TPU) films, demonstrating how key parameters (stretching temperature, stretch ratio, strain rate) determine their mechanical and functional properties. The results identify an optimal processing window (110°C and a 2.5 × 2.5 stretch ratio), yielding an elastic recovery of 89.2%, a 250% increase in strength, and a retained fracture elongation of 1000%. Finite element simulations reveal the deformation patterns, showing that the optimal conditions produce a uniform stress distribution (32.1 MPa), whereas over–stretching causes severe stress concentration (86.0 MPa) near the clamping roots, with fracture prediction errors below 8%. The process–structure–property relationship demonstrates that efficient molecular chain alignment leads to an entropy–driven elastic network. These results provide both general insights and practical guidance for developing high–performance TPU films for high–volume packaging applications.