Determination of the mechanical properties of hydrogen storage tanks and computer aided modeling

Keywords: AA6061, AA6063, AA6082 Al Mg Si alloys, high-pressure hydrogen storage tanks, the finite element analysis of hydrogen tanksIn this thesis, computer aided design and analysis of liners, seamless aluminum tubes used as high-pressure composite hydrogen storage tanks, are done. The mechanical properties and the microstructures of prototypes are examined.In this study, the beavior of tubes made from AA6061, AA6063 and AA6082 which are alloys of 6000 series used to manufacture tanks, are investigated. Tubes are examined whether they meet the quality standards.This thesis is partly supported by San-Tez (Industrial Thesis Program of the Ministry of Industry and Commerce). In this San-Tez 123 project, for the first time in Turkey, Research and Development studies of high-pressure hydrogen storage tanks are carried out and prototypes are manufactured. The behaviors of the prototype tanks made from 6000 series Al Mg Si alloys are analysed with the finite element methods under high pressure. The prototypes manufactured for each alloy are tested with hydrostatic pressure tests and both results are compared.In the scope of the thesis, for each prototype made from AA6061, AA6063, AA6082 alloys, the hydrostatic pressure tests and finite element analyses are repeated according to their heat-treatment status of No Treatment, T4 and T6. Tensile specimens are produced and the stress-strain curves are obtained. The data is inserted to the computer model to analyse. Moreover, the microstructures of the tanks after plastic deformation are examined to understand the variation in their structure. Hardness distribution and microscope images were inspected. The internal forms resulted due to the heat treatment are observed by XRD analysis. Non-destructive tests, radiographic examination, liquid penetrant testing and ultrasonic thickness measurements are done. The protoype tanks are evaluated in the light of the information obtained from these tests.The main purpose of the thesis is to determine the mechanical properties of seamless aluminum tubes by the help of computer modelling and finite element methods. Furthermore, it is also aimed to identify the most ideal alloy type and the most suitable heat treatment way.