Test Validated Multi-Scale Simulation of a Composite Bumper Under Impact Loading

In a recent USAMP-DOE Validation of Material Models study sought to evaluate efficacy of computational software against physical test. The undertaking started with material characterization and sub-element verification in Phase I and continued to full bumper assembly evaluations. A multiscale ICME building block approach for calibration, verification, and validations resulted in good agreement between test and simulation and served as the foundation for the blind prediction of a composite bumper under impact loading. Comparisons show that simulations, utilizing LS-DYNA® User Material with GENOA’s Multi-Scale Progressive Failure Analysis (MS-PFA), under predicted test displacement vs time and generally over-predicted force curves. Under prediction in displacement was attributed to variation in boundary conditions between test and simulation. Discrepancy in force was assumed to be due to rigid simulation joints/boundary conditions, voids/defects/waviness in physical part, and discrepancy in as-designed vs as-built part. Another factor for discrepancy was that as-designed CAD model was different than as-built physical model, causing more failure/crush/deformation in test since distortion could place undesired higher moments on assembly resulting in increased stresses at fittings. Predictions are improved with direct input of void shape/size and fabric waviness as part of analytical de-homogenized approach which scales to component level without excessive cost in CPU time.