Stochastic Process Modeling of a Prepreg Platelet Molded Composite Bracket

Abstract

Prepreg platelet molding compounds (PPMCs), formed by slitting and cutting prepreg tape, are used to produce complex parts with moderate structural performance while maintaining good processing characteristics associated with compression molding. The fiber orientation state in the final part is driven by the processing (i.e. the initial orientation state of the preform and the flow). Then, the fiber orientation distribution within the structure determines its mechanical performance. However, there can be significant part to part variability for these systems which is accommodated through reduced design allowables. A recently developed molding simulation methodology predicts the final fiber orientation state given the initial conditions. Yet, the variability of the initial orientation state caused by preform deposition can contribute significantly to the variability in part microstructure, particularly for low flow processes. The method for anisotropic flow and fiber orientation analysis was employed to analyze the molding of a bracket geometry. Initial orientation states were stochastically generated. The predicted orientation state was transferred to a structured mesh to perform a structural analysis and obtain the part stiffness. The predicted stiffness was used as a metric to assess the ability to predict variability caused by stochastic initial conditions. The resulting predicted stiffness and variability were consistent with mechanical testing.