Systematic Parameter Selection for Short Fiber Polymer Composite Direct Fiber Simulation

ABSTRACT The orientation of fibers in short discontinuous fiber reinforced polymer composites is a critical factor in determining final mechanical and thermal properties. Tensor‐based models of fiber orientation are common but require difficult‐to‐obtain model parameters and are limited by assumptions. Direct fiber simulations (DFS) models individually simulate fibers and their interactions with each other and the surrounding fluid. The motion of fibers simulated in DFS is determined by interaction models which require proper calibration to accurately simulate a given fiber material system. An automated generalized method of parameter selection for DFS using surrogate model‐based optimization is developed for short fiber polymer composites processing. A DFS model is presented and subjected to the calibration for fibers with a 15.64 aspect ratio at a volume fraction of 8% in simple shear flow. To demonstrate the process, this system is calibrated using Jeffery's Orbit, a theoretical pARD tensor model, and an experimentally obtained orientation distribution function. The calibrated DFS model results are shown to agree well with targeted fiber behavior and provide unique insight into the contact mechanics of fiber interaction. Further, a DFS model calibrated to experimental results is used to obtain orientation tensor model parameters from simple physical experiments and demonstrate enhanced insight available from the data‐rich simulations. Results appearing here illustrate the advantages realized through the use of commercially available discrete element software for simulating short fiber composite suspensions.