Design development and testing of a morphable vehicle underbody shield actuated by shape memory alloys

Shape memory alloy (SMA) actuated composites enable real-time geometry modification for enhanced automotive aerodynamic performance. However, integrating SMAs into polymer matrices presents significant challenges in thermomechanical coupling and interface reliability under cyclic loading conditions. This study investigates SMA-polymer active composites for vehicle underbody shield applications through integrated experimental-computational methods. The approach combines multiphysics finite element modeling with precision manufacturing protocols, incorporating SMA-based actuators into a hybrid PC/ABS-carbon fiber reinforced polymer system. Multiple configurations with varying actuator densities and composite layer architectures (2-3 plies) were systematically characterized. The optimized configuration achieves 30 mm deflection at 135 °C with peak stresses below 435 MPa, demonstrating a displacement-to-length ratio of 0.4. The validated multiphysics framework predicts system behavior within 5% of experimental measurements. A scalable three-phase manufacturing protocol (carbon fiber reinforced polymer lamination, component assembly, SMA integration) enables consistent production of meter-scale adaptive structures while maintaining precise geometric tolerances. This research establishes new performance benchmarks for morphing automotive components through validated design methodologies. Future development should focus on thermal management optimization for enhanced durability under varied environmental conditions.