A physically-based deformation model for the resin pocket geometry prediction of smart composites embedded with FBG sensor

Smart composites embedded with Fiber Bragg Grating (FBG) sensors are gaining popular in aircraft structures due to their self-sensing and monitoring capabilities. Resin pocket around FBG sensor would be formed in the forming, which could deteriorate the mechanical properties of composite host. Therefore, high fidelity prediction of resin pocket geometry is important for assessing its deterioration impact. A physically-based deformation model was proposed to predict the resin pocket geometry. Temperature dependent hypo-viscoelastic constitutive law was used to describe the material behavior of unidirectional (UD) prepreg. To achieve the tension-bending decoupling, superimposed membrane-shell element was used for UD-prepreg. Curvature dependent nonlinear bending stiffness was accounted in the model. Simulations of FBG senor embedding into flat and curved laminate structures were performed. Good agreement was noted for the resin pocket geometry between simulations and experiments, demonstrating the efficiency and high accuracy of the proposed model.