Investigations of Residual stresses in FRP composite by Relaxation techniques - An experimental approach

In the present work, efforts were made to determine the residual stress in laminated composites by three semi destructive methods: Hole Drilling, Ring Core, and Slitting. Unidirectional (UD) Glass-Epoxy(GE) composite [0(4)/90(4)](s) were prepared by compression molding technique with the pressure of 10 kg/cm(2), the temperature of 120 degrees C with 10 min holding time. The pulse method was used to approximate the initial residual stresses in all three methods. The calibration coefficient matrices were obtained by finite element (FE) simulation of each relaxation process. The strains in all three methods increased with the depth of cut. The strains in the Ring core method are higher than the Slitting method and hole drilling method. Furthermore, the residual stresses obtained from the Ring core method are higher followed by the Slitting method. Copyright (C) 2022 Elsevier Ltd. All rights reserved.