Modelling of Mechanical Properties of Thermoplastic Elastomer for Simulation of Belt Welding Process

Abstract

Hot plate welding is a popular method for butt joining drive and conveyor belts made of thermoplastic elastomers. A crucial step in this technological operation is the plasticisation of the belt material on a hot plate, which occurs under the influence of locally elevated temperature and the action of axial compressive force. Due to the multiplicity of parameters in the plasticisation process, there are opportunities for its optimisation, mainly in terms of energy efficiency. Such an action can positively impact the energy consumption of the welding operation, and, thus, the entire belt manufacturing process. The paper presents the results of numerical and experimental studies on the modelling of the mechanical properties of a polyurethane-based thermoplastic elastomer used in the manufacture of belts. In the first stage of the experimental studies, the stress response of the material to displacement was determined based on the results of a static tensile test. The obtained stress–strain characteristics were used to perform numerical tests using the finite element method. In this stage of the work, various types of hyperelastic material models, including Mooney–Rivlin, Ogden, Neo-Hooke, Yeoh, Arruda–Boyce, and Marlow, were used to map the static tensile test in the simulation. Based on the assessment of the convergence of numerical and experimental results, three hyperelastic models were selected that could be used to model the properties of this material; these were the second-order polynomial, the third-order Ogden, and the fourth-order Ogden. Additionally, based on observations from the first stage of experimental and numerical studies, it was determined that modelling the mechanical deformation process of this belt may require the use of a material model that takes into account the deformation speed. These observations were confirmed during the second stage of experimental research, where a static tensile test showed the effect of strain rate on the stress–strain characteristics, which may suggest the need to refine the hyperelastic model by incorporating viscoelasticity. The results and conclusions from the physical tests will be used to further refine the numerical model, which will be used during the optimisation of the belt plasticising operation.