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This problem is reduced to two usual mmachine problems and a solution algorithm is designed.


A Minimax Planar Location Problem with Forbidden Zones: Its Solution Algorithm


The concept of a riskguaranteed solution for manycriteria problems under uncertainty, which is typical of emergency situations, and a solution algorithm for these problems are described in Part I of this paper.


A parametric identification problem is formulated and its numerical solution algorithm is designed.


A numerical solution algorithm for the problem is designed.

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 It is important but also difficult to study threedimensional elastoplastic finite element analysis of aeroengine structures, which have a complex configuration and various heavy loads. The stress distribution in the engine struc ture is a necessary datum for fracture mechanics and fatigue damage. For this reason the stresses in elastic and plastic zones deserve to be taken into accountin many engineering fields.In order to ensure adequate accuracy, a spatial 20nodes isoparametric element is selected and a... It is important but also difficult to study threedimensional elastoplastic finite element analysis of aeroengine structures, which have a complex configuration and various heavy loads. The stress distribution in the engine struc ture is a necessary datum for fracture mechanics and fatigue damage. For this reason the stresses in elastic and plastic zones deserve to be taken into accountin many engineering fields.In order to ensure adequate accuracy, a spatial 20nodes isoparametric element is selected and a straightforward numerical solution methodan efficient method of Front Solveris adopted. For saving computational time and reducing main memory space, a cubic fourteen points Gaussian integral is applied. Moreover, with the aim of economizing manpower and gaining quite high accuracy the cubic finite element meshes are automatically generated.The programming is also discussed in general, including constitutive equations, solution algorithm and strategy for solving large problems. Practice has shown that the program written by author is very advantageous to solving elastoplastic problems.Two typical specimens for experimental investgation are provided: a notched thick plate in which the local stresses are higher than the nominal applied stresses, and a thick plate with a central hole in which the stress distribution along the inside edges is also higher than that of the other place. The theoretical analyses and the experimental results coincided favourably.  本文用有限元法对三维弹塑性的应力与应变进行了分析,文中将非线性求解和数值积分做了改进,使计算时间缩短;三维元素的各种信息自动生成,提高了输入数据的精度和效率。用本法计算的各种实例与实验数据进行比较,二者吻合甚佳,能满足工程上所要求的精度。  A turbine disk is known as one of the important parts of a jet engine. In the design and analysis of its damage tolerance, it is necessary to determine the critical crack length aic exactly. Using the cracks at the bottom of firtree slots of the first stage turbine disk in an existing engine as an example, by means of the breakdown test and elaborate theoretical calculation, the criterion and the solution algorithm to determine the critical crack length aic are provided. It is suggested that the condition... A turbine disk is known as one of the important parts of a jet engine. In the design and analysis of its damage tolerance, it is necessary to determine the critical crack length aic exactly. Using the cracks at the bottom of firtree slots of the first stage turbine disk in an existing engine as an example, by means of the breakdown test and elaborate theoretical calculation, the criterion and the solution algorithm to determine the critical crack length aic are provided. It is suggested that the condition under which the engine could not normally operate be regarded as the critical state for the crack. In view fo the complexity of turbine disk shape and loading conditions, the authors have employed "twice evaluation algorithm'' for Jintegral in the elastoplastic fracture mechanics. This algorithm comes out simpler and more accurate than those presented in literature.  涡轮盘是航空发动机的重要零件之一,在进行损伤容限的设计和分析中,需要准确地确定其临界裂纹长度α_(IC)。本文以一实际发动机Ⅰ级涡轮盘槽底裂纹为实例,通过破裂试验和细致地理论计算分析,得出确定临界裂纹长度α_(IC)的准则和具体方法;并且提出用破坏其正常工作状态的条件作为临界裂纹状态的判别条件。作者们还针对涡轮盘几何形状复杂和承受载荷复杂的特点,在进行弹塑性断裂力学的J积分计算时,采取了二次计算法,既简便又有较高的精度。  In this paper, the fuzzy trial and the hybrid element method based on the mixed variational principle are used in solving the unified buckling analysis of thick and thin plates. Compared with the results obtained from other finite element analyses and with classical solutions, the numerical solutions give better accuracy. In addition, this paper also discusses the positive definiteness of the element stiffness matrix and some practical techniques of solution algorithm of generalized eigenvalue problems.... In this paper, the fuzzy trial and the hybrid element method based on the mixed variational principle are used in solving the unified buckling analysis of thick and thin plates. Compared with the results obtained from other finite element analyses and with classical solutions, the numerical solutions give better accuracy. In addition, this paper also discusses the positive definiteness of the element stiffness matrix and some practical techniques of solution algorithm of generalized eigenvalue problems.  本文应用模糊试解和基于混合变分原理的杂交元方法,进行了厚、薄板的屈曲分析,与解析解及其它有限元解相比,其数值精度优良.文中还讨论了所得单元刚度矩阵的正定性以及广义特征值求解算法的实施技术.   << 更多相关文摘 
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