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用 Groebner 基法求机构学问题的符号形式的解 总被引:4,自引:1,他引:3
应用Groebner基法对机构学问题的非线性代数系统进行求解。在生成该系统的封闭形式的“三角化”的Groebner基的基础上,求出了问题的封闭形式的符号解,以平面铰链四杆机构的刚体导引综合问题为例,说明该方法的思路及有效性。 相似文献
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基于单调性分析与符号处理技术的套筒滚子链优化设计通用解 总被引:1,自引:0,他引:1
本文利用单调性分析和计算机符号处理技术对套筒滚子链进行优化设计,求出了通用形式的最优解,这一最优解适用于具有各种参数的同一类模型,对于具体问题,只要将已知参数值代入就可得到最优解之值,同时这一方法不需进行数值优化中的迭代。 相似文献
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设计规律性知识的获取是智能设计要解决的基本问题之一。本文根据工程问题符号表达的优化设计模型的特点,提出了一种求解符号优化模型的方法,利用该方法可求出一类问题的最优解的用非线性代数系统的标准基(Groebner基)来描述的解析表达式,从而得出有规律性的知识和指导设计。 相似文献
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基于Groebner基法和计算机符号处理技术,对三自由度并联机床的位置正解问题进行了符号求解。该法通过对变量排序。建立多项式对的集合,求SP多项式,约简等运算,将一组非线性方程组化简为同价的三角化方程组,得到了封闭形式的解析解;导出了雅可比矩阵,引入了符号处理技术,并且对该并联机床的可操作性进行了分析,给出了具体数值实例。 相似文献
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Hyungho Chun Sang Jik Kwon Taeoh Tak 《Journal of Mechanical Science and Technology》2008,22(2):276-286
A multibody approach is suitable for tolerance analysis of mechanical systems since multibody formulation can directly consider
part-level tolerance variables. In this study, procedures for performing tolerance analysis and corresponding sensitivity
analysis for spatial multibody systems are proposed. First, statistical formulation for performing multibody system tolerance
analysis is developed to obtain system level tolerance for given part-level tolerances. One very useful aspect of the proposed
formulation is that in the process of computing system tolerance, the sensitivity of system tolerance with respect to part-level
tolerances can be additionally obtained. The kinematics of spatial multibody systems has been redefined in terms of both generalized
coordinates and part-level tolerance variables. Tolerances in geometry of a body are specified in terms of the variations
in relative locations of joint definition points and relative distance between them. Tolerances in the joint kinematics are
defined through variations in vector closure equations and orthogonality equations that are two fundamental constraint equations
for most kinematic joints. To demonstrate the validity and effectiveness of the proposed tolerance analysis procedure, tolerance
analysis of a spatial 4-bar mechanism and tolerance optimization are performed. 相似文献
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The current research of the decomposition methods of complex optimization model is mostly based on the principle of disciplines, problems or components. However, numerous coupling variables will appear among the sub-models decomposed, thereby make the efficiency of decomposed optimization low and the effect poor. Though some collaborative optimization methods are proposed to process the coupling variables, there lacks the original strategy planning to reduce the coupling degree among the decomposed sub-models when we start decomposing a complex optimization model. Therefore, this paper proposes a decomposition method based on the global sensitivity information. In this method, the complex optimization model is decomposed based on the principle of minimizing the sensitivity sum between the design functions and design variables among different sub-models. The design functions and design variables, which are sensitive to each other, will be assigned to the same sub-models as much as possible to reduce the impacts to other sub-models caused by the changing of coupling variables in one sub-model. Two different collaborative optimization models of a gear reducer are built up separately in the multidisciplinary design optimization software iSIGHT, the optimized results turned out that the decomposition method proposed in this paper has less analysis times and increases the computational efficiency by 29.6%. This new decomposition method is also successfully applied in the complex optimization problem of hydraulic excavator working devices, which shows the proposed research can reduce the mutual coupling degree between sub-models. This research proposes a decomposition method based on the global sensitivity information, which makes the linkages least among sub-models after decomposition, and provides reference for decomposing complex optimization models and has practical engineering significance. 相似文献
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机床床身是机床的重要部件,它起着支撑立柱、工作台等部件的作用,其性能的好坏直接影响到机床的加工精度。在对HX7910五面加工中心床身结构动态优化设计过程中,建立HX7910五面加工中心床身的有限元模型,分析了其前六阶模态。根据分析结果确定筋板为优化对象,采用灵敏度优化法首先对床身内部筋板结构参数进行动态灵敏度分析。在灵敏度分析基础上,进行结构优化设计,得到了较优的结构参数,提高了加工中心床身的动态特性,从而提高床身的性能。 相似文献
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在Newton法的基础上,提出了一种新的迭代格式,并论证了其收敛性,该方法具有二次收敛的特点,比一般迭代法收敛快。 相似文献
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An efficient approach for shape optimization of components 总被引:2,自引:0,他引:2
The optimization problem of finding the optimal shape of a mechanical component is investigated with the aim of presenting a simple and efficient numerical approach for minimizing stress concentration factor. The proposed approach is based on finite element method in conjunction with the widely used fully stressed design criterion (or the axiom of uniform stress), i.e. for structural shape optimization, an essential requirement for optimality is the achievement of constant tangential stresses along a section of the boundary to be optimized. The design boundary is modeled by using cubic splines, which are determined by a number of control points. The optimal shape of the design boundary with constant stress is achieved iteratively by adjusting the design boundary shape based on a simple logic and algorithm. The result quality in terms of accuracy and efficiency are tested and discussed with finite element analysis examples. The approach presented has the attractive properties that it can be very simply implanted into standard finite element codes. 相似文献