Carbon fiber reinforced polymer composites are drawing great attention in theautomotive industry due to their lightweight, high stiffness/strength properties. Fiberreinforced prepregs in various fabric architectures are preformed to a designed partshape before a final compression molding of the parts. Most of the current numericalsimulation techniques are developed for woven composites, which are fabricated withbi-axial fiber orientations. There is no modeling technique for braided and NCF (Non-Crimped Fabric) prepregs with tri-axial fiber directions.In this paper, the authors’ previous work on bi-axial woven prepregs is extended tomodel the tri-axial braided prepregs based on a one-step analysis approach. Thealgorithm developed for this analysis treats the matrix and fibers as different materials.Any material model in the commercial FEA software can define the matrix, while thefiber is modeled as an elastic material. The material deformation on the final formedpart is obtained by using the minimum energy method. This feature has beensuccessfully implemented in LS-DYNA and can be activated by the modifiedkeyword: *DEFINE_FIBERS. No tooling information is needed for the model setup.The initial prepreg shape and size can be obtained based on the final part geometry.The prediction accuracy and computational efficiency of the developed one-stepanalysis is demonstrated through modeling the preforming of a double dome part.Good agreement is obtained in the initial prepreg size prediction when compared toexperimental data.
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