CRASH BOX DESIGN FOR FRONTAL IMPACT PROTECTION ON RESERVE ENERGY STORAGE SYSTEM (RESS)

• Main Author: Armando, Egidius
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/51521
• Institution: Institut Teknologi Bandung

CRASH BOX DESIGN FOR FRONTAL IMPACT PROTECTION ON RESERVE ENERGY STORAGE SYSTEM (RESS) Electric vehicle development still has a limitation on its Reserved Energy Storage System (RESS) which is susceptible to fire incident when the vehicle is involved in a crash accident. Crash energy, if not controlled, will be able to mechanically deform the battery cell inside RESS which triggers the fire incident. Hence, a lightweight energy absorbing structure is needed as an impact energy absorbent during crash. Low structure mass allows the vehicle to achieve higher fuel efficiency. In the automotive industry, thin-walled columns are commonly used as crash boxes. They are typically placed in vehicle frontal structure to absorb impact energy during frontal crash by forming plastic deformation. This research was carried out to obtain optimum crash box design which has good crashworthiness performance during frontal crash simulation on electric bus chassis. The loading condition was based on FMVSS 208 regulation while preserving the stress threshold on the battery model (tensile cut-off) after crash within 10 MPa. Numerical simulations using LS-DYNA were done in two stages. First, simulations on 16 variations of multi-cell crash boxes, and second, simulations on a chassis system with installed battery model and selected multi-cell crash boxes. The triggering mechanism was applied to crash boxes in the chassis model to generate progressive crushing during crash box deformation instead of global buckling. From the first stage simulation result, there are 8 potential multi-cell crash box candidates, which are the cross-section A, B, C, D, E, F, G, and H with 5 mm thickness. These 5 mm crash boxes have better performance of SEA, CFE, and use shorter crushing distance when compared to the cross-section A, B, C, D, E, F, G, and H with 4 mm thickness. In the second stage simulation, the chassis system installed multi-cell crash boxes A, B, C, D, E, F, G, and H with 5 mm thickness demonstrated excellent crashworthiness performance. These 8 type crash boxes capable to absorb all crash energy, but only chassis installed with crash box F5, G5, and H5 managed stress on the battery model below a threshold value. Stresses on each battery model after crash sequentially are 8.20 MPa, 8.51 MPa, and 5.47 MPa. The most optimum design is the F5 crash box due to progressive crushing deformation formed during impact while stress on the battery model after crash is the lowest. In this research, an increasing number of cells inside the multi-cell crash box was proven to improve crashworthiness parameters, therefore capable to secure the RESS on the chassis during a frontal impact.