Simulation of Softening and Rupture in Multilayered Fuel Tank Material 2019-28-2557
Multi-layered, high-density polyethylene (HDPE) fuel tanks are increasingly being used in automobiles due to advantages such as shape flexibility, low weight and corrosion resistance. Though, HDPE fuel tanks are perceived to be safer as compared to metallic tanks, the material properties are influenced by service temperature. At higher temperatures (more than 80oC), plastic fuel tanks can soften, sag and eventually spill out the fuel, while the extreme cold (less than -20°C) can lead to potential cracking problems. Damage may also occur due to accidental drop while handling or due to an impact from a flying shrapnel. This can be catastrophic due to flammability of the fuel. The objective of this work is to characterize and develop a failure model for the plastic fuel tank material to simulate damage and enhance predictive capability of CAE for chassis and safety load cases. Different factors influencing the material properties such as service temperature, rate of deformation, state of stress etc. were considered to develop a characterization and modelling strategy for the HDPE fuel tank material. Samples cut-out from different regions of the fuel tank were subjected to various tests such as tensile test at different strain rates viz. 0.01/s, 0.1/s, 1/s, 10/s and 100/s, compression, shear, flexure and instrumented dart impact tests at different temperatures, -40°C, 23°C and 85°C. Simulation of damage was accomplished via progressive damage and failure modeling capability available in ABAQUS. Ductile damage initiation criteria and equivalent plastic displacement for damage evolution were considered. The parameters of the failure model were optimized using Design for Six Sigma (DFSS) principles. The material model was validated by comparing simulation results with test at coupon and component levels.