Numerical solutions for crack problems during elastomer forming

Abstract

Generically, thermoset elastomers are often referred to as rubber. It is characterized by the chemical bonding between polymer chains. One of the important problems that plague elastomer manufacturing and rubber parts under service is cracks. Predicting the main factors affecting crack propagation trajectories during forming and after curing time is an important challenge. For this purpose, numerical analysis was implemented by using the commercial ABAQUS/CAE software package. A three-dimensional model was established to predict the important factors that affect this process. During the analysis, the effect of forming velocity and the amount of kinetic energy on the distortion of rubber material and crack propagation is explored in detail by using different forming punch velocities. The drop velocity of the upper insert (punch) on the rubber pad was taken as 10 m/s, 7 m/s, and 5 m/s, respectively. Consequently, while each forming velocity will generate different kinetic energy between the interaction surfaces, the change in crack behavior and the normal stress can be monitored in different positions. As a result, among these velocities, it was found that the low forming velocity of the upper insert (punch) is better than the others in forming rubber where cracks and distortions were at minimum values. Also, the amount of kinetic energy is low enough in the case of low speeds and can affect the results significantly. In addition, it was found that the generated stresses have a significant impact on the crack development in a specific area, especially near the fillets and sharp edges. It was concluded that calculating the parameters affecting the crack growth and predicting the crack propagation trajectories using the finite element method is a significant method for predicting and solving crack problems before tool fabrication