A study on simple piping elbow finite elements

Rights statement
Awarding institution
  • University of Strathclyde
Date of award
  • 1990
Thesis identifier
  • T6661
Qualification Level
Qualification Name
Department, School or Faculty
  • Three new simple beam-shell piping elbow finite elements have been formulated and programmed as User Elements for the ANSYS finite element program. The elements share a common beam bending model, based on an exact solution of Vlasov's thin-walled beam theory, but adopt different ovalisation interpolation schemes. In the first element, PB 1, ovalisation deformation is assumed constant with respect to axial position and interpolated circumferentially by an even Fourier series. The second element, PB2, extends the PB 1 formulation to include linear interpolation of ovalisation with respect to axial position. In the third element, PB3, constant ovalisation deformation is interpolated piecewise around the cross-section by four quintic polynomial functions. Several s~ple analyses of single bends were performed, and the results compared with published theoretical and experimental results. PB 1 and PB2 were found to give good agreement with stresses from alternative solutions for a range of elbow geometries. The element PB2 solution converged slightly more rapidly than PB 1, but the additional degrees of freedom required for linear interpolation negated the advantage of the higher order scheme. Element PB3 performed poorly in comparison with the other elements, especially in the analysis of elbows of low bend parameter. It was concluded that the polynomial interpolation scheme of element PB3 was less effective than Fourier interpolation of ovallsation. Of the three elements presented, element PB1 was chosen in preference to PB2 for general piping analysis as its complete stiffness matrix had been obtained in closed form, making it computationally less expensive. The use of element PB 1 in piping system analysis was investigated by performing several sample analyses of systems and comparing results with flexibility and finite element analysis. It was found that the element gave accurate results at low computing costs, indicating its suitability for general elastic analysis of piping systems.
Advisor / supervisor
  • Boyle, J. T. (James T.)
Resource Type