Investigation of the Spring-In of a Pultruded L-Shaped Profile for Various Processing Conditions and Thicknesses

In this study, a thermo-mechanical finite element model is developed to predict the spring-in of an industrially pultruded L-shaped profile made of glass/polyester composite. The resin curing kinetics are obtained from the differential scanning calorimetry (DSC) experiments. The development of the resin modulus is derived using the dynamic mechanical analysis (DMA) tests and the effective mechanical properties of the processing composite are calculated using a micromechanical model. The temperature and degree of cure distributions are obtained in a three dimensional (3D) thermo-chemical anlaysis using the finite element method (FEM). The process induced distortions are then calculated using these distributions in a 2D quasi-static mechanical analysis in which generalized plane strain elements are utilized. The predicted spring-in pattern at the end of the process is found to agree quite well with the one observed for the real pultruded parts in a commercial pultrusion company. In addition, the effects of the pulling speed and the part thickness on the spring-in formations are investigated using the proposed numerical simulation tool. It is found that the magnitude of the spring-in increases with an increase in the pulling speed and part thickness.