Development of Fuel Sloshing Evaluation Technique upon Crash 2019-01-0941
In the development of fuel tank systems, it is important to maintain fuel system integrity even if a car accident occurs. When a fuel tank undergoes a sudden change in velocity, the fuel starts to move and deforms tank shells and baffle plates, and then the deformation changes the flow pattern of fuel. Because interaction of tank components with fuel is the main cause of fuel spillage upon crash, predicting complex fluid-structure interaction behaviors at an early stage of crash safety development with a multiphysics simulation is important. Development of the multiphysics simulation technique was conducted stepwise by examining fluid motion, tank deformation, and contact between fuel tank and body frames that progressively deform during crash. First, a sled test of a rigid-wall tank with observation window was conducted to verify fluid motion inside the tank. A numerical model was developed based on an ALE (Arbitrary Lagrangian Eulerian) method for the fluid and Lagrangian method for the structure. The fluid-structure interaction uses a penalty method, and three different fluids: gas and fuel inside the tank and air outside the tank are modeled and coupled with fuel tank components. A sled test of an actual fuel tank was then conducted. Distribution of tank shell residual deformation was measured and compared with simulation. The simulation accurately reproduced bulging and contraction deformation due to sloshing of fuel and negative pressure induced by an increase in tank volume, respectively. Finally, a rear impact test was conducted with a moving deformable barrier. Even in conditions where body frames progressively deformed and interfered with the fuel tank, the simulation well reproduced the fuel tank deformation. As a result of the above study, the simulation technique became an effective tool for assessing risk of fuel spillage at an early stage of crash safety development.
Kazuya Yamauchi, Koji Yoshimura, Yu Hanada, Kosuke Kojima