Elastoplastic nonlinear analysis of nozzle-cylinder intersections subjected to internal and external loads
Mansouri, Sameer A.
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Permalink
https://hdl.handle.net/2142/20687
Description
Title
Elastoplastic nonlinear analysis of nozzle-cylinder intersections subjected to internal and external loads
Author(s)
Mansouri, Sameer A.
Issue Date
1991
Doctoral Committee Chair(s)
Schnobrich, William C.
Department of Study
Civil and Environmental Engineering
Discipline
Civil Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Engineering, Civil
Language
eng
Abstract
A three-dimensional finite element analysis utilizing quadratic isoparametric elements is applied to the cylindrical connection. The finite element mesh is highly refined in the three principal directions in the critical regions of sharp discontinuity of geometry and material. Convergence of the mesh is continuously examined to ensure a converged finite element solution.
This study concludes that experimentally derived solutions may contain serious shortcomings. Specifically, the outcome is not reliable and should be seriously questioned, such as in this study. The experimental setup may contain shortcomings which include the placement and distribution of the strain gauges. The consequences of these conditions are compounded by questions of the validity and adequacy of linear extrapolations of the recorded data to the regions of interest.
This study also includes an elasto-plastic nonlinear analysis of the intersecting cylinders problem. This step is a natural extension for a structure that exhibits stress concentration factors up to 52.4. The high ductility of the steel typically used to construct cylindrical connections provides a high potential for the steel to regain strength by plastification and redistribution of high stress values. High ratios of failure loads to yield loads (known in some field applications as the shape factor) is observed, ranging between 3.19 and 6.8. An appreciable degree of the yield load of similar but undisturbed components is restored in the elasto-plastic range (percentage ratio of the failure load of the connection to the yield load of similar dimensions plain pipes are between 21 and 73%. These values are to be contrasted with the high stress concentration factors of up to 52.4). The analysis is verified against available experimental data to ensure quality and provide reliability. This entails comparisons being made at the locations of experimental data acquisition and the element model being constructed to model what are anticipated to be the actual conditions present in the experimental setup. The nonlinear finite element analysis is demonstrated to be reliable and affordable in both time and expense; thereby, it is an effective and efficient tool for analysis and design of the cylindrical connection in the elasto-plastic range. (Abstract shortened with permission of author.)
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