In this investigation, a systematic surrogate-based optimization design framework for a battery pack is presented. An air-cooling battery pack equipped on electric vehicles is first designed. Finite element analysis (FEA) results of the baseline design show that global maximum stresses under x -axis and y -axis transient acceleration shock condition are both above the tensile limit of material. Selecting the panel and beam thickness of battery pack as design variables, with global maximum stress constraints in shock cases, a multi-objective optimization problem is implemented using metamodel technique and multi-objective particle-swarm-optimization (MOPSO) algorithm to simultaneously minimize the total mass and maximize the restrained basic frequency. It is found that 2nd order polynomial response surface (PRS), 3rd order PRS and radial basis function (RBF) are the most accurate and appropriate metamodels for restrained basic frequency, global maximum stresses under x-axis and y-axis shock conditions respectively. Results demonstrate that all the optimal solutions in Pareto Frontier have heavier weight and lower frequency compared with baseline design due to the restriction of global maximum stress response. Finally, two optimal schemes, “Knee Point” and “lightest weight”, satisfied both of the stress constraint conditions, show great consistency with FEA results and can be selected as alternative improved schemes.

The proper assembly of underground precast concrete structures is often critical in the construction of underground structures. In particular, interfacial waterproofing between precast concrete...

Due to the complexity of the valve systems in vehicle dampers, the components exhibit synergistic and coupling effects during operation. To comprehensively investigate the interaction mechanisms of critical internal structures within the damper, this paper proposes a finite element modeling method for different operating conditions, and analyzes the dynamic characteristics of the damper. For low-velocity conditions, the computational fluid dynamics (CFD) method is employed for modeling and simulation to investigate the oil flow rule under the throttling effect of orifices only. The length and entrance area of the orifices are found to have a significant impact on the low-velocity damping force. Following the CFD model, a fluid-solid interaction (FSI) model is successively established for the medium- and high-velocity conditions to analyze the interaction between the deflecting valve systems and the oil in the damper. The inner and outer diameters of the valve seat, and the disc valves stiffness are found to have a significant impact on the medium- and high-velocity damping force. The simulation results indicate that the deviation of the damping force is less than 5% and 10% for CFD and FSI models, respectively. During the valve systems opening process to overcome the preload, the flow rate distribution between the valve opening gaps and orifices fundamentally changes, with most of the oil flowing through the valve opening gaps. At this time, a larger deflection occurred in the high pressure region of the disc valves, and the deflection is uniform along the radial direction. The maximum valve opening gaps of the valve systems are all less than 0.5 mm, while the compensation and flow valve systems open earlier and larger than the rebound and compression valve systems, which highlights the sensitivity of the damping force to the stiffness of the disc valves. The modeling method proposed in this paper can be targeted to investigate different velocity conditions of the damper, reducing model complexity while improving simulation efficiency and confidence level, and providing guidance for damper performance design and optimization.