Finite Element Structural Analysis of a Thick-walled Pressure Vessel

  • Joseph Mutava Jomo Kenyatta University of Agriculture & Technology
  • John Kihiu Jomo Kenyatta University of Agriculture & Technology
  • Onesmus Muvengei Jomo Kenyatta University of Agriculture & Technology
  • Kenneth Njoroge Jomo Kenyatta University of Agriculture & Technology

Abstract

Finite Element Analysis (FEA) is a practical numerical solution tool which can be utilized in determining the stress state in a pressure vessel, especially in local areas such as cavities, O-ring grooves and other areas which would be difficult to analyze manually. A lot of work has been done in developing various numerical and experimental methods to study stresses in pressure vessels. Generally, these studies focus on structural elastic analysis of the pressure vessels since it is a common design practice to aim at maintaining the induced stresses within the elastic region. However, pressure vessels operate under complex environments such as high pressure and temperature, which may lead to gross plastic deformation and subsequent failure. Again, in autofrettage process, the pressure vessel is pressurized beyond the yield point. As a result, the conventional elastic analysis will not be applicable at internal pressures above the yield point. Therefore, it is important to examine the structural integrity of a thick-walled pressure vessel in both elastic and plastic state of the material. In this study, FE static structural analysis of a presumably uncracked thick-walled pressure vessel has been presented, where stress dis-tribution within the pressure vessel wall and the resulting material deformation were investigated using ANSYS 14.5.7. ANSYS is one of the FE-based design softwares that have become valuable tools in engineering design. Both elastic and plastic analysis were carried out on a plain cylindrical pressure vessel model and on a cylindrical pressure vessel model with a nozzle geometry included. It was observed that the stress distribution in the pressure vessel in the elastic stress state was totally different to that in the plastic stress state. Geometric discontinuity due to a nozzle was found to affect the stress distribution in a large scale. Stress concentration in the areas around the nozzle neck made it impossible to overstrain a thick-walled pressure vessel to a fully plastic state (as required for a fully autofrettaged pressure vessel) without having failed. The FEA results obtained were verified by comparing them with some theoretical results. Better agreement between FEA and theoretical results was obtained for elastic analysis than for plastic analysis. The aim of the study was to contribute to the need of a complete structural analysis of pressure vessels.
Published
Jun 13, 2016
How to Cite
MUTAVA, Joseph et al. Finite Element Structural Analysis of a Thick-walled Pressure Vessel. Proceedings of Sustainable Research and Innovation Conference, [S.l.], p. 174-185, june 2016. ISSN 2079-6226. Available at: <http://sri.jkuat.ac.ke/ojs/index.php/proceedings/article/view/423>. Date accessed: 23 nov. 2017.

Keywords

Finite element analysis; Structural analysis; Thick-walled pressure vessel; ANSYS.