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Vibration calculation of pipeline systems with arbitrary branches by the hybrid energy transfer matrix method

THIN-WALLED STRUCTURES 2023年 183卷

作者： Yin-hang, Cao Gong-min, Liu Zhi, Hu Harbin Engn Univ Coll Power & Energy Engn Harbin 150001 Peoples R China Harbin Engn Univ Yantai Res Inst Grad Sch Yantai 264006 Peoples R China Harbin Engn Univ 145 Nantong St Harbin 150001 Heilongjiang Pr Peoples R China

The transfer matrix method (TMM) is an analytical method for investigating the vibrations in many structures such as beams, pipes, sheets, and shells. For long-span pipeline systems conveying fluid, the vibration solution method based on the TMM suffers from numerical instability when calculating in high frequency. In this paper, the hybrid energy transfer matrix method (HETMM) is built to analyze the vibration of pipeline system while avoiding the numerical instability problem. It can be directly and easily derived from the proven TMM. The calculation matrix dimension and form do not change with subunits number. The calculation program hardly varies, and the calculation time is short. So, the trial calculation can be carried out with little to no cost to determine the appropriate subunits *** branched pipes of arbitrary shapes are prevalent in pipeline systems. The HETMM for fluid-filled pipeline system with any branched pipes is proposed in this paper, too. A dominant chain of the pipeline system is selected, and the influence of branched pipes at the junction will be "absorbed"by the dominant chain. Several numerical examples are presented to illustrate the application and stability of the proposed method. Results from the present approach are validated by measured and numerical data. Finally, the first-order natural frequency of a double-branch pipeline system is optimized combining the HETMM and the complex method. Through these examples, it is shown that the HETMM is efficient, stable in high frequency and can be used to calculate and optimize branched pipes of any shape.

关键词： The transfer matrix method Numerical stability The hybrid energy transfer matrix method Branched pipes the complex method

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A Nonlinear Optimization Algorithm for Lower Bound Limit and Shakedown Analysis

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CMC-COMPUTERS MATERIALS & CONTINUA 2010年第3期20卷 251-271页

作者： Gang, G. Liu, Y. H. China Special Equipment Inspect & Res Ctr Beijing 100013 Peoples R China Tsinghua Univ Dept Engn Mech Beijing 100084 Peoples R China

Limit and shakedown analysis theorems are the theories of classical plasticity for the direct computation of the load-carrying capacity under proportional and varying loads. Based on Me lan's theorem, a solution procedure for lower bound limit and shakedown analysis of three-dimensional (3D) structures is established making use of the finite element method (FEM). The self-equilibrium stress fields are expressed by linear combination of several basic self-equilibrium stress fields with parameters to be determined. These basic self-equilibrium stress fields are elastic responses of the body to imposed permanent strains obtained through elastic-plastic incremental analysis by the three-dimensional finite element method (3D-FEM). the complex method is used to solve the resulting nonlinear programming directly and determine the maximal load amplifier. The numerical results show that it is efficient and accurate to solve three-dimensional limit and shakedown analysis problems by using the 3D-FEM and the complex method. The limit analysis is treated here as a special case of shakedown analysis in which only proportional loading is considered.

关键词： Limit and shakedown analysis 3D-FEM self-equilibrium stress nonlinear programming the complex method

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Numerical determination of limit loads for three-dimensional structures using boundary element method

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EUROPEAN JOURNAL OF MECHANICS A-SOLIDS 2004年第1期23卷 127-138页

作者： Liu, YH Zhang, XF Cen, ZZ Tsinghua Univ Dept Engn Mech Beijing 100084 Peoples R China

Based on the static limit analysis theorem, a solution procedure for limit analysis of three-dimensional (3-D) structures is established making use of conventional boundary element method (BEM) rather than of finite element method (FEM). The self-equilibrium stress fields are expressed by linear combination of several basic self-equilibrium stress fields with parameters to be determined. These basic self-equilibrium stress fields are elastic responses of the body to imposed permanent strains obtained through elastic-plastic incremental analysis by three-dimensional boundary element method (3-D BEM). the complex method is used to directly solve the resulting nonlinear programming problem and to determine the maximal load amplifier. The numerical results show that it is efficient and accurate to solve 3-D limit analysis problems by using BEM and the complex method. (C) 2003 Elsevier SAS. All rights reserved.

关键词： limit analysis 3-D BEM self-equilibrium stress nonlinear programming the complex method

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Boundary element methods for lower bound limit and shakedown analysis

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ENGINEERING ANALYSIS WITH BOUNDARY ELEMENTS 2004年第8期28卷 905-917页

作者： Zhang, XF Liu, YH Cen, ZZ Tsing Hua Univ Dept Engn Mech Beijing 100084 Peoples R China

Limit and shakedown theorems are exact theories of classical plasticity for the direct computation of the load-carrying capacity under constant and varying loads. Based on Melan's theorem, a solution procedure for limit and shakedown analysis is established making use of symmetric Galerkin boundary element method (SGBEM) for two-dimensional (213) structures and traditional boundary element method (BEM) for three-dimensional (313) structures. The self-equilibrium stress fields are expressed by linear combination of several basic selfequilibrium stress fields with parameters to be determined. These basic self-equilibrium stress fields are elastic responses of the body to impose permanent strains obtained through elastic-plastic incremental analysis by SGBEM for 2D structures and by BEM for 3D structures, respectively. the complex method is used to solve resulting non-linear programming directly and determine the maximal load amplifier. The numerical results show that it is efficient and accurate to solve limit and shakedown analysis problems by using the BEM and the complex method. In this paper, the limit analysis is treated as a special case of shakedown analysis in which only proportional loading is considered. (C) 2003 Elsevier Ltd. All rights reserved.

关键词： limit analysis shakedown analysis symmetric Galerkin boundary element method boundary element method self-equilibrium stress nonlinear programming the complex method

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