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Heavy electric quadricycles (L7e) typically have the problem of crash incompatibility because their size and weight are smaller and lighter than other vehicles. The S-rails, located in front of the automotive underbody, are the main components for absorbing the impact energy of the L7e. The design of the L7e's S-rail for crashworthiness is challenging because the design space is relatively limited. High computational resources are commonly required for crash simulation due to a vast amount of data from nonlinear explicit dynamic analyses. Machine learning techniques can more quicky provide and extract accurate crash predictions from a combination of feasible solutions. This work employs a finite element analysis via LS-DYNA to obtain discrete results of the peak crushing force and the specific energy absorption for S-rail impact. The artificial neural network (ANN) module in MATLAB and response surface methodology (RSM) were then applied to predict the crushing-performance surrogate models based on the S-rail's thickness and geometry. To conduct an accurate learning process of the ANN, 81 data points for the crashworthiness simulation were adopted as training inputs with ten test data points. Furthermore, the number of neurons and activation function are examined to acquire the most accurate results for predicting the dynamic crushing of an S-rail. The investigation shows that ANN is more accurate than RSM in predicting the S-rail's peak crash force and specific energy absorption, especially when applying ReLU activation functions. With its high accuracy and capability to predict multiple targets, the ANN-ReLU is recommended to perform surrogate-based model optimization. [ABSTRACT FROM AUTHOR]

Crash boxes are typically designed to promote characteristics in energy absorption from progressive buckling during impact. However, the conventional design often has limitations in lightweight design and passenger protection. Thus, truss-lattice and cellular structures offering superior energy-absorbing capacity are implemented in crash box design. This work investigates the crushing behaviors and characteristics of square-tube crash boxes filled with truss-lattice and cellular structures with the objectives of lightweight design while improving the specific energy absorption and mean-crushing forces and lowering the initial peak crash force. The crushing efficiency of the crash boxes between four different types of structures: conventional, BCC, FCC, and Primitive-TPMS, are evaluated and compared using the nonlinear explicit dynamics finite element technique via LS-DYNA. The lattice and cellular structures perfectly show progressive deformation under impact with an excellent potential to absorb energy. The nodal equivalent technique is recommended for the model analyses for the crash boxes with filler structures. The fillers are shown to enhance the crashworthiness of the conventional crash box by controlling the whole deformation so that it remains progressive bucking failure. According to the analysis results, a crash box filled with Primitive-TPMS presents the highest crushing performance and this design is proposed for next-generation vehicles. [ABSTRACT FROM AUTHOR]

Safety requirements and lightweight have been the primary considerations in designing automotive parts. The selection of materials with high specific strength, energy absorption, and specific stiffness properties, such as aluminum and fiber-reinforced composites, paves the way to resolving this challenge. This study investigates and compares the energy absorption characteristics and pedestrian protection of the automotive front bumper beam made of aluminum, carbon fiber-reinforced epoxy (CFRE), and glass fiber-reinforced epoxy (GFRE) with the steel counterpart. The baseline steel bumper beam under a high-velocity frontal crash to a rigid wall at 50 km/h was first analyzed using finite element analysis through LS-DYNA. The bumper beams of other lightweight materials were designed with identical energy absorption capacity. They were then assessed through the low-velocity crashes according to UN-ECE R42 regulation and Euro NCAP pedestrian testing protocol. Although the aluminum bumper beam deformed less in crash tests, it possessed the lowest specific energy absorption (SEA) and the highest peak force. The quasi-isotropic CFRE and GFRE composite beams attained higher SEA because the stresses could be efficiently distributed in the beams, as observed from more extensive damage areas, especially in the ±45°-plies. From a proposed effective parameter weighted from the peak force, maximum deformation, energy absorption, mass, and cost, the GFRE bumper was recommended for modern car bumper beams. The optimal design of the GFRE bumper beam could substantially improve crashworthiness compared to the baseline steel beam with a weight reduction of 67.7%, a 101.8% increase in the SEA, and a 59.8% decrease in the peak force. Furthermore, the pedestrian's lower leg protection was further achieved by adjusting the beam's position. [ABSTRACT FROM AUTHOR]

Crash box is the main component of the crumple zone to absorb impact energy. Therefore, it requires the highest energy absorbing performance under axial and oblique impact loads at different angles. This study presents an optimal solution for the hexagonal crash box design with a functionally graded thickness (FGT) honeycomb filler. The crash box finite element model was firstly validated with the experimental impact test. Layer sensitivity analysis of the FGT model showed that using 41 layers along the crash box axis was sufficient to obtain accurate results. The multi-objective optimization was adopted to obtain the optimal grading exponents of the FGT crash box that maximize specific energy absorption (SEA) and minimize initial peak crash force (IPF) at the 0-, 10-, 20-, and 30-degree impact angles based on the Particle Swarm Optimization technique. The optimal FGT design could decrease the IPF in all design cases compared to the crash with uniform thickness (UT), while the SEA of the FGT crash box demonstrated better crashworthiness at the 30-degree impact angle. Furthermore, the FGT crash box exhibited the progressive failure mode at the oblique impact angles, which resulted in higher energy absorbing capability than the bending failure mode observed in the UT crash box. [ABSTRACT FROM AUTHOR]