Flange Design Study in Fuel Delivery Module for Robustness and Crash Worthiness Using Computational Simulations 2015-26-0154
This paper discusses about the Flange design study carried out in Fuel Delivery Module (FDM) for meeting out contradictory requirements of robustness and crash worthiness. FDM is assembled in the fuel tank with flange covering the tank opening, and swirl pot assembly comprising fuel pump attached to flange through two steel struts.
During crash, FDM undergoes sudden deceleration. Due to inertia, swirl pot assembly creates bending moment in the flange-strut interface. At such adverse condition, flange should not exhibit crack on the sealing side, as it might expose fuel in the fuel tank to the atmosphere. To ensure safety, flange-strut interface in the bottom side of flange is designed with higher stress concentration factor. So, the struts along with swirl pot assembly will break away from flange during crash without creating crack in the flange sealing faces.
But failures were observed during vibration testing in the flange-strut interface with new stringent vibration requirements. Hence, a study was carried out on the flange design with different notch radius and outer boss radius. Three design variants were prepared with the variation of these parameters and extensive investigations were carried out using computational simulations with vibration and crash conditions. Based on Finite Element Analysis (FEA) results of vibration simulations done with acceleration load applied on driving & opposite direction, approximate fatigue life estimation was carried out. With these results, better design variant was chosen, so that it meets out both crash & vibration requirements with capability to withstand higher fatigue stress life cycle.