Crystal plasticity finite element models typically assume each grain starts with a spatially uniform dislocation distribution, meaning each grain is initialized with a single lattice orientation and all grains share the same slip resistance. This study assessed that assumption by comparing crystal plasticity simulations of tensile tests against experiments on an extruded aluminum 7079 alloy. The simulations utilized computational microstructures with ‘pancaked’ grains and a significant degree of crystallographic texture, consistent with experimental measurements. In one case, the computational microstructures were assigned a single slip resistance and a single lattice orientation for each grain prior to the tension tests. In another case, the extrusion process prior to the tension tests was simulated to cause nonuniform slip resistances, nonuniform crystal orientations within each grain, and nonuniform slip resistances at each material point. Both approaches produced reasonably accurate predictions of the measured yield stress and lateral strain ratio anisotropy, but the predictions considering the initial nonuniformity exhibited less prediction error. Other factors, such as latent vs self hardening of slip systems and fine vs coarse grains, did not have as large an impact. These results suggest that dislocation heterogeneity should be experimentally characterized and fed into future crystal plasticity simulations.

The composite thermo-hydroforming process, utilizing heated and pressurized fluid, was used to form an advanced helmet with the Spectra Shield. Experimental results obtained from the forming process show that thermo-hydroforming is a feasible process for manufacturing thermoplastic composite materials. Concurrent to the forming experiments, the forming process was numerically modeled using ABAQUS/CAE. The behavior of the fiber reinforced polymer composite was modeled using the Preferred Fiber Orientation model, which was implemented into the explicit finite element code ABAQUS by writing a User Material Subroutine. The preferred fiber orientation model was further adapted to work with a composite laminate consisting of multiple layers. Numerical results were compared with experimental data to validate the method in terms of predicting the deformed geometry of the multilayer composite, wrinkling, as well as the punch force–displacement curve. Overall, the deformed shape of the fiber-reinforced thermoplastic composite helmet, including the distribution of wrinkles were predicted accurately.