E. Haugeneder, H.A. Mang, W. Prochazka:
"Plastic Analysis of a Pipeline Component";
in: "Proceedings of the Second SAP User's Conference", University of Southern California, Los Angeles, USA, 1977, 15.
Tests have shown that the two flanges connecting the casing of a ball cock with adjacent pipes have experienced cracks when subjected to approximately 1.5 times the operating pressure. In the present case the ball cock is used as a shutoff device for a pipeline. The conventional mode of analysis of such flanges is only of limited value. This fact has suggested an elastic - perfectly plastic finite element (FE) analysis of the prototype of a flange connection together with the adjacent casing of the ball cock and a part of the attached pipe. A close examination of the spreading of plastic zones and of the magnitudes of the principal normal stresses permits a better assessment of the danger of failure of the flange at various pressure intensities.
Two preprocessors and a postprocessor have been developed for the program system NONSAP, which has been used for the analysis. One preprocessor serves the purpose of efficiently plotting the given FE mesh. The other one is devoted to the automatic conversion of uniformly distributed surface loads to work-equivalent nodal forces. The postprocessor enables graphic identification of plastic regions.