Date of Award

2017

Document Type

Open Access Master's Report

Degree Name

Master of Science in Mechanical Engineering (MS)

Administrative Home Department

Department of Mechanical Engineering-Engineering Mechanics

Advisor 1

Gregory M. Odegard

Committee Member 1

Adam Loukus

Committee Member 2

Jeremy Worm

Abstract

The purpose of this study is to computationally model and analyze a Conformable Compressed Natural Gas (CNG) fuel tank for frontal crashes using Finite Element Analysis. Researchers have developed a CNG fuel tank, which is conformable, non-conventional and non-cylindrical. This tank increases cost efficiency, volumetric efficiency and cargo efficiency in CNG vehicle applications. A lightweight pickup truck (2015 Chevrolet Silverado) has been used to integrate the CNG tanks and field-testing has been conducted to demonstrate the application.

The report mainly focuses on the effective finite element modeling of the chassis, brackets and tanks using HYPERMESH and RADIOSS. The frontal crash analysis is simulated according to FMVSS 208 standard for two impact velocities of 35 mph and 55 mph. CAD models of the brackets have been developed for this study. Material models of the truck chassis and bracket are developed using the available data.

An important aspect of this study is to determine an appropriate way to model the CNG tank. The conformable tank’s complex geometry, limitations in the software capabilities and the high computational expenses posed a challenge in this study. An equivalent tank model, having a simpler geometry has been developed and used for this study. The effective modulus of the equivalent tank was determined by equating the strain energy of the conformable tank to the strain energy of the equivalent tank, both subjected to same loading.

The results obtained from the crash analysis conclude that the tanks do not fail in frontal crash and rear crash, and the positioning of the tanks are validated. Recommendation for future work is also provided at the end of this report.