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Large-Diameter Directly Buried Heating Pipe 90° Elbow Fatigue Life of the Finite Element Analysis

Author: WangGuoWei
Tutor: WangFei
School: Taiyuan University of Technology
Course: Heating,Gas Supply, Ventilation and Air Conditioning Engineering
Keywords: Large caliber direct burial elbow Fatigue life Finite Element Internal pressure loads Displacement load
CLC: TU995.3
Type: Master's thesis
Year: 2010
Downloads: 137
Quote: 2
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Abstract

With the continuous expansion of the centralized heating-scale, large-diameter, high-pressure buried heating pipe universal application, diameter size has reached DN1400. But no domestic force calculated standard for large-diameter buried pipe clear, especially elbows, follows the the DN500 procedures design theory, be reduced to a point, still use the elastic bending hinge analytical method for stress calculation, engineering a large number of The set fixed pier and compensation to protect the elbow. In this paper, the mechanical study of the large-diameter buried heating elbow, complex force, displacement, the accurate calculation of the stress can be reached to reduce the use of the number of fixed pier and compensator, to reduce the project cost, accelerate the construction speed enhanced pipeline network reliability purposes. In this paper, large-diameter buried heating elbow, do the following aspects of work: 1. Comprehensive stress analysis: consider the weight of the pipeline as well as the medium itself buried heating pipe of large diameter, the buoyancy of the groundwater table, tube top overburden gravity, the traffic load on the ground as well as the role of accumulation of load on the vertical load of the large-diameter buried heating pipe theoretical analysis of selected closer to the actual pipe stress formula. Brief introduction elbow processes, elbow defects in the process: the uneven wall thickness, elliptical cross-section. These will inevitably affect the elbow stress the size and the stress distribution situation, provides a theoretical basis for the finite element model. Further analysis Buried technical regulations in the domestic DN500 less the elbow stress calculation method, through a large number of calculations and analysis of the calculation results show that the design pressure of the pipe network, depth, temperature difference between cycle work, the radius of curvature of the elbow and the corner the size of the level of buried heating the carrying capacity of the pipe section of the vertical angular elbow have different degrees of influence, wherein the circulating working temperature, the most obvious effects of the radius of curvature of the elbow and the angular pipe section angularity. Norms on foreign construction process of the elbow, and the fatigue life checking simple introduction to the theoretical basis of these as a finite element numerical calculation. Load is applied to the finite element model, the selection of parameters, and provides a theoretical basis. Using finite element software on the the ideal elbow, ranging from wall thickness elbow, ovalization elbow inner pressure load displacement load (temperature load) under the numerical simulation. Obtained from the simulation results, the various factors affecting the quantitative relationship of the Elbow maximum equivalent stress. Curve fitting, fitting out the the ideal elbow largest equivalent stress and internal pressure loading, displacement load relationship. On this basis, ranging through the elbow wall thickness and ovalization of correction can be obtained by a simple calculation of the actual elbow accurate numerical results. Finally, through engineering examples prove that to simplify formulas reasonable. Existing DN500 less direct burial technical regulations continue to apply to large-diameter buried heating elbow fatigue strength checking, too conservative, and can not give full play to the potential of the elbow.

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CLC: > Industrial Technology > Building Science > Municipal Engineering > Urban central heating > Heat pipe network
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