Modification Of Forest Dislocation-based Crystal Plasticity Model And Its Application In Crystal Plasticity Finite Element Modeling

With the widely application of Crystal Plasticity Finite Element Modeling(CPFEM)on predicting the deformation behavior of materials,phenomenological models have shown great insufficiency.These models are gradually being replaced by physics-based ones,such as all kinds of dislocation density-based models.Forest dislocation-based strengthening model,which generally accounts for the interaction between mobile dislocations and forest dislocations,is concise in physics and thus being widely used.However,forest dislocation-based strengthening model cannot account for the interactions between coplanar dislocations.This doesn't only make forest dislocation-based strengthening model imperfect,but also leads to a lack of restraint against favored slip systems,resulting in unusual distortion.By analyzing the interactions between dislocations,interaction of coplanar dislocations is induced into the model to overcome the stability problem.It can also make the model more complete in physics to account for all interactions between dislocations.Then the two dislocation-based models are used to predict the tensile behavior of single slip and multiple slip of single crystal,and the shear band distribution of rolled Aluminum sheet.When modeling single slip,two dislocation models predict almost the same result.When modeling multiple slip,forest dislocation-based model leads to distortion,while modified dislocation model can predict a stable result.And by comparing with the shear band distribution of rolled Aluminum sheet,the shear band is over-estimated as a result of the instability of both model and material.By introducing self-hardening,the modified dislocation based model can overcome the instability,so its result can truly reflect how material behaves during distortion.Modified dislocation-based model has overcome the instability problem of forest dislocation-based strengthening model by inducing coplanar dislocation interactions.The range of material parameters is broadened and simulating efficiency is improved.