Car chassis can be considered as the primary protective shield for the safety of the passenger during rear-end crashes. This study focuses on the deformation and failure behavior of the frontal car A-pillar chassis frame when subjected to collision with a heavy vehicle. Two different angles of the A-pillar chassis frame use are 45-degree and 70-degree. The crash simulation is conducted by using Finite Element software under the explicit dynamic. The car chassis frame geometries are designed by using SolidWorks 2021 and imported to the finite element software while a rigid block is designed in the finite element software as a rigid body to replicate the heavy vehicle. The chassis body is simulated for two types of materials, Aluminum alloy, and steel. The car speed impacted at 60 km/h. Results show that the intrusion of a rear barrier for 45 degrees of aluminum alloy will stop at 0.03 s but for 70 degrees it will intrude the car frame until the end. For the steel car frame, 45 degrees design is capable to withstand the intrusion of a rear barrier from a serious deform but for 70 degrees the intrusion will continue until the end. Car frame crush behavior, energy dissipation, and vehicle decelerations from the crash simulation were observed.

This paper studies the numerical failure mechanism of the solder joints in the ball grid array (BGA) package under thermal reliability process. The package consists of the silicon die, the Flame Retardant 4 (FR-4) substrate and the FR-4 printed circuit board (PCB). A total of 64 95.5Sn-4.0Ag-0.5Cu (SAC405) solder joints with a diameter of 0.46 mm are arranged together in area array fashion with a pitch distance of 0.8 mm. Only a quarter-model of the package is simulated since all the geometry, loading and boundary conditions (BC) is symmetry at the centre of the package. The package is exposed with thermal loading, initially at the liquidus temperature of 220°C to room temperature (25°C). Then, it follows with 3 additional thermal cycles between 125°C and -40°C with a ramp rate of 11°C/min and 15 minutes dwell time, respectively. Unified inelastic strain model (Anand model) was used to compute the inelastic behaviour of the solder joints. Results show that the stress level at the critical solder joints and the corresponding inelastic strain are 39.91 MPa of 0.2083%, respectively after the end of the solder reflow cooling process. As predicted, the inelastic strains accumulate continuously in the solder joint throughout the temperature cycles. Additionally, in the critical solder joint, both high stress and inelastic strain gradients are localized near to the solder-IMC interfaces. Prolong the thermal cycles can extensively accumulate the inelastic strains which lead to fatigue crack and subsequently crack propagation in the solder joints. After the end of the FE simulation, the highest stress and inelastic strain predicted are 57.96 MPa and 0.5781%, respectively.

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