15 th International LS-DYNA ® Users Conference June 10-12, 2018 1 Test Validated Multi-Scale Simulation of a Composite Bumper Under Impact Loading 1 Cody Godines, 1 Frank Abdi, 1 Saber Dormohammadi, 1 Michael Lee, 2 Akbar Farahani, 2 Morteza Kiani 1 AlphaSTAR Corporation, Long Beach, California 2 Engineering Technology Associates, Inc. Troy, Michigan Abstract 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. 1.0 Introduction Advanced hybrid (continuous, chopped) composite structures are finding wide-spread applications in the automotive industry (Figure 1), primarily due to their high specific stiffness and strength, in addition to their improved impact performance, when compared to conventional metallic alloys. This is further assisted by the increased confidence gained through extensive developments in composite structural design, analysis, and manufacturing, allowing advanced composites to be used in modern commercial fleet, particularly in their primary structures [1][2]. Structural responses of composites to dynamic and critical loading conditions is complex. Failure in composite structures range from tensile and compressive matrix and fibre failure to delamination of the individual plies that is caused by inter and intra-laminar cracks. Composites exhibit anisotropic behaviour with generally high longitudinal and transverse strengths. However, they also sustain substantial damage along the through-thickness axis due to their poor strength properties in that direction. Figure 1. Advanced Hybrid Composite: Continuous and Chopped Fiber (SMC) Simulation