Characterization and Simulation of Viscoelastic Shear Behavior of Woven Prepregs During Compression Molding

The ongoing molding simulation for woven-reinforced thermosetting composites is crucial for in-depth exploration into the mechanical performance and optimization design of composite materials. This study explores the in-plane shear mechanical behavior of thermosetting woven prepregs under viscoelastic effects, integrating mechanical experiments, theoretical analysis, and finite element simulations. A generalized Maxwell viscoelastic constitutive model, based on the Prony series, is developed to describe the shear behavior of woven prepregs and implemented in an Abaqus user subroutine. Macroscopic shear stress relaxation experiments at various temperatures and loading rates provide input data for the model, and then the viscoelastic parameters are validated through bias-extension tests and hemispherical molding. The analysis demonstrates that the prepreg's in-plane shear deformation significantly impacts the shear angle distribution and quality of molded components. It also reveals temperature as the most sensitive parameter affecting shear behavior. Despite minor errors attributed to the irreversible microstructural changes, the proposed model achieves high accuracy and efficiency, offering a robust tool for optimizing forming processes of woven composite materials.