Specifying the allowed remained bottom thickness after milling in CNG steel cylinders by FEM analysis and experimentation

Journal of Simulation and Analysis of Novel Technologies in Mechanical Engineering

مقاله 7، دوره 14، شماره 1، خرداد 2022، صفحه 67-75   

نوع مقاله: Research article

نویسندگان

Mojtaba Esmailian^{* 1}؛ Mohsen Shahmoradi²؛ Kamran Karimzadeh³

¹Faculty of Mechanical, Malek Ashtar University of Technology, Iran

²Department of Mechanical Engineering, Malek Ashtar University of Technology, Isfahan, Iran

³Engineering Department, Pars MCS Co, 8465197569 Esfahan, Iran

چکیده

In CNG steel cylinders produced by the hot spinning method from seamless tubes, homogeneity of the material in the closed-end region is a significant factor. Therefore, in the production process, the produced cups are immediately under a hot heavy press, and in addition to forming the bottom shape, the heterogeneous area is driven out, finally, this region is eliminated via machining. Ideally, the depth of this milled area should be to the extent that the heterogeneous region is completely removed, also according to the designing standards, the minimum bottom thickness shall be more than that of wall thickness. However, the problem is that controlling this parameter is impossible in the machining process, and in some cases, it may become more than the specified limit. In this research, the minimum allowed remained thickness after bottom milling has been obtained by analysis and also compared with real results acquired from static and fatigue tests. Deducing the results of the FEM analysis, it can be seen that the remained bottom thickness up to 6mm has no limitation for the endurance hydrostatic pressure, and that was supported by experimental burst tests. Considering this amount for the bottom thickness, the percentage of rejected products declined considerably from 4% to 2% in the factory.

کلیدواژه‌ها

CNG steel cylinders؛ Hot spinning؛ Heterogeneous region machining؛ FE analysis

مراجع

[1] Moss, Dennis R., (2004), Pressure vessel design manual, illustrated

procedures for solving major pressure Problems. 3rd.

[2] ISO 9809 Standard, (2010), Gas cylinders — Refillable seamless steel gas cylinders - Design, construction, and testing.

[3] ISO 11439 Standard, (2013), Gas cylinders, High-pressure cylinders for the on-board storage of natural gas as a fuel for automotive vehicles.

 [4] Li, H., Huang, X., Yang, P., Yang, H., (2017), A new pressure vessel design by analysis method avoiding stress categorization, International Journal of Pressure Vessels and Piping, 152, 38-45.

 [5] Ahmadi Borughani, Y.,  Faghani, H., (2009), Design and fatigue analysis of CNG cylinders type 1 according to international standards, Ninth international manufacturing conference, Birjand University, Iran, 2009.

 [6] Shariati, M., Mohammadi, E., Masoudi Nejad, R., (2017), Effect of new specimen size on fatigue crack growth behavior in thick-walled pressure vessels, International Journal of Pressure Vessels and Piping, 150, 1-10.

 [7] Zoghi, H., Fallahi Arezoodar, A., Sayeaftabi, M., (2013), Enhanced finite element analysis of material deformation and strain distribution in the spinning of 42CrMo steel tubes at elevated temperature, J Materials, and Design, 47, 234–242.

 [8] Huang, C-C., Hung, J-C., Hung, C., Lin, C-R., (2011), Finite element analysis on neck-Spinning process of tube at elevated temperature, The International Journal of Advanced Manufacturing Technology, 56, 1039–48.

 [9] Lexian, H., Dariani, BM., (2008), An analytical contact model for finite element analysis of tube spinning process, Proceeding of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture, 222, 1375–85.

 [10] Liu, JH. Yang, H., Li, YQ., (2002), A study of the stress and strain distributions of first-pass conventional spinning under different roller-traces, Journal of Materials Processing, 129,  326–329.

 [11] Zhang, X., Zhao, L., Wen, T., (2017) An optimized neck-spinning method for improving the inner surface quality of titanium domes, International Conference on the Technology of Plasticity, 17-22.

 [12] Maghsoodi, M., H., Monajatizadeh, Alaee, A.R., (2013), Hot pressing effects on the mechanical properties after hot spinning in CNG cylinders, NCME Conference, Tehran, Iran.

 [13] Hibbitt K, Sorensen. (2001)  ABAQUS CAE user’s manual. Hibbitt, Karlsson & Sorensen, Inc.