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Date of Award

2016

Document Type

Campus 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 Odegard

Committee Member 1

Ibrahim Miskioglu

Committee Member 2

Paulus J van Susante

Abstract

The purpose of this study is to conduct structural optimization of a non-conventional CNG (Compressed Natural Gas) fuel tank. Most of the commercially used CNG tanks are cylindrical in shape. This project is a part of a larger project to develop non-cylindrical CNG tank. In phase I of the project, rectangular tanks will be developed. In Phase II, conformable shape tanks will be designed. This study focusses on topology optimization of the tank structure of Phase I tanks. It also presents a brief study on Drop Test simulation of the tank.

The Topology optimization analysis was conducted using FEA (Finite element analysis) packages Hypermesh and Optistruct. The results show that optimized tank design has 28 % less mass as compared to the original structure. As per the optimized geometry, material on the edges of the tank can be toned down while some material could be added to the face of the tank.

The Drop test was simulated as per NGV2 standards using the software packages Hypermesh and Radioss. The results show that the stresses in the tank are above the ultimate tensile strength of 55,000 psi. These results do not match with the experimental observations which show very minor plastic deformation in the tank. This discrepancy can be due to use of improper material properties for the drop test simulation. Hence further studies need to be conducted on it.

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