Modeling continuous laser ablation of glass fiber-reinforced epoxy resin plate with two-dimensional finite element

As a kind of high temperature resistant material, glass fiber-reinforced epoxy resin (GFRE) plate is widely used in aviation and machinery fields. When GFRE is exposed to high temperature and high-speed airflow, it undergoes severe ablation, which affects its material and internal structure. In order to investigate the thermal effects and ablation behavior under high heat flux, a continuous laser was used to ablate a GFRE plate with different laser power levels. Then, a two-dimensional finite element model of laser ablation of GFRE was developed, taking into account the depth-dependent absorption of laser energy and the enthalpy change caused by the pyrolysis reaction. The mass loss results from the model were compared with those from the experiment and showed reasonable validity. Moreover, the changes in the internal composition of GFRE during ablation were also analyzed based on the experiment and model. It was found that the epoxy resin content decreased rapidly during ablation while the dehydrated epoxy resin and carbides increased continuously. Dehydration reaction was found to be the main factor for mass loss. Furthermore, the surface layer had more heat dissipation by convection and radiation than the deep layer. Hence, the chemical reactions in the surface layer ceased almost instantly after stopping the laser. However, the chemical reactions in the deep layer persisted for some time after removing the heat source.