Opportunities and challenges of multiscale modeling and simulation in polymer composite processing

Composite processing, due to their heterogeneous nature, complex chemistry of the resin, its interaction with fibres and fillers and simultaneous transport of mass, momentum and energy at the nano, micro, meso and macro levels eludes formulation of process models from first principles. Hence most researchers have resorted to the use of constitutive equations along with conservation laws at the macro level to describe the relationship between various process parameters. Constitutive equations are empirical relations that endeavour to incorporate the physics observed from the experiments or studied and analyzed at the micron and molecular level into the equations at the macro scale. Almost all constitutive equations require the researchers to characterize constants needed in the equation that are specific to the material and its state. This paper will provide examples of various approaches used in our research to introduce the phenomenon observed at the micron and molecular level in process models to predict the influence of various material, geometric and process parameters on the resulting microstructure in composite manufacturing. The various pitfalls and short comings in modelling will be identified and the opportunities and challenges in integrating the physics occurring at the multi scale level into a coherent process models will be discussed. The role of numerical modelling and simulation in furthering our understanding at the micro and molecular levels and presenting the results in the form of interest to the process engineer will be accentuated with pedagogic examples. Some thoughts on how process models and their simulations can be integrated on the manufacturing floor to improve product reliability and repeatability will be provided.