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基于几何法的结构可靠度计算 总被引:2,自引:0,他引:2
本文用几何法计算了结构的可靠度,并给出了相应的计算公式及程序流程图。最后通过算例以Monte-Carlo法的解为基准,对一次二阶矩法及改进的一次二阶矩法与几何法进行了比较,结果表明几何法具有收敛速度快,精度高,迭代次数少等优点,为结构可靠度的计算提供了有力的理论和事实依据,并得出了很多有益的结论。 相似文献
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大型结构体系可靠度分析的探讨大庆石油管理局总机械厂张士军,齐桂荣一MOnteCarlo概率模拟法与结构力学或有限元相结合在静力可靠度问题分析中常用的正态变量法所求的计算结果是可靠性指标B,当已确认功能函数Y一L—S为正态分布时.用伍来确定结构的可靠度... 相似文献
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模糊分析方法在机械设计中的应用 总被引:4,自引:0,他引:4
一.前言在现实生活和工程设计领域中,存在着许多不确定现象,它主要表现在两方面:一是随机性,一是模糊性。前者是由于事物的因果关系不确定所造成的,它属于概率统计研究的范畴。后者是因边界不清楚所造成的,它是指其在质上没有确切的含义,在量上没有明确的界限。不确定性是事物的一种客观属性,是事物发展过程中存在着亦此亦彼或中介过渡状态的结果。例如,对于滚动轴承类型的选择,在同一工况下,有时各人会有各人的选择;对于材料的选用,制造某种零件往往也并不是非某种材料不可,…。这就是事物的模糊性。这些问题之所以模糊,是由于涉及的因素太多,且有些因素 相似文献
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模式识别,对我们来说并不是一件陌生的事情。比如我们在人群中找一个人,就是把所见到的人和记忆中的形象比照,当看到了一个和记忆中的形象一样的人时,就找到了那个人。这个找人、辨别、比照的过程就是模式识别。本文所说的模式识别是指给定工作情况,要从现有的模式(如结构类型、材料)中选择与所给条件最贴切的模式。模糊模式识别分为直接方法与间接方法两大类,今分述如下。 相似文献
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基于模糊分布参数的元件和结构系统的可靠性度量指标分析 总被引:7,自引:1,他引:7
在元件强度和外载的分布参数未知的情况下,本文提出了利用已有试验和专家经验采用模糊数对这些未知参数进行了定量描述,并给出基于可靠度指标和基于失效概率的两种元件的可靠性度量指标估计方法。比较这两种指标的结果表明,对于正态型的分布和隶属函数,基于失效概率的元件可靠性度量指标更能反映参数模糊性对元件的安全程度的影响。本文提出了方法还可以推广应用于结构系统,从而给出结构系统诸分布参数为模糊数时的可靠性度量指 相似文献
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现代机械零件不仅承受各种复杂机械载荷,还可能工作在热、电、磁、流体的环境中,因此零件设计不仅要考虑机械载荷,还应对其它因素的作用进行计算,本文在介绍了有限元分析软件功能,有限元分析软件的静力、动力分析方法基础上,介绍了机械设计中复杂结构有限元分析中问题的处理。 相似文献
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机械可靠性分析与设计的一种显式迭代算法 总被引:2,自引:0,他引:2
基于改进的一一次二阶知釜对机械可靠性分析和单一设计变量的机械可靠性设计问题,本文提出了计算结构可靠度和确定结构可靠性参数的一种显式迭代算法。与有关文献相比较,这种方法优点是无需解域变换、无需人工计算功能函数的偏导数和无需解结构失效的极限状态方程具有较为简便的计算形式和较高的计算效率,可方便地算出结构的可靠度和结构可靠性参数。本文方法具有一阶计算精度。 相似文献
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Ziling Zhang Zhifeng Liu Ligang Cai Qiang Cheng Yin Qi 《The International Journal of Advanced Manufacturing Technology》2017,91(5-8):1547-1566
Accuracy design constitutes an important role in machine tool designing. It is used to determine the permissible level of each error parameter of a machine tool, so that any criterion can be optimized. Geometric, thermal-induced, and cutting force-induced errors are responsible for a large number of comprehensive errors of a machine tool. These errors not only influence the machining accuracy but are also of great importance for accuracy design to be performed. The aim of this paper is the proposal of a general approach that simultaneously considered geometric, thermal-induced, and cutting force-induced errors, in order for machine tool errors to be allocated. By homogeneous transformation matrix (HTM) application, a comprehensive error model was developed for the machining accuracy of a machine tool to be acquired. In addition, a generalized radial basis function (RBF) neural network modeling method was used in order for a thermal and cutting force-induced error model to be established. Based on the comprehensive error model, the importance sampling method was applied for the reliability and sensitivity analysis of the machine tool to be conducted, and two mathematical models were presented. The first model predicted the reliability of the machine tool, whereas the second was used to identify and optimize the error parameters with larger effect on the reliability. The permissible level of each geometric error parameter can therefore be determined, whereas the reliability met the design requirement and the cost of this machining was optimized. An experiment was conducted on a five-axis machine tool, and the results confirmed the proposed approach being able to display the accuracy design of the machine tool. 相似文献
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Design of axial fan using inverse design method 总被引:3,自引:0,他引:3
Kyoung-Yong Lee Young-Seok Choi Young-Lyul Kim Jae-Ho Yun 《Journal of Mechanical Science and Technology》2008,22(10):1883-1888
The axial fans for cooling condensers were designed by inverse design code TURBOdesign-1. The parameters of the inverse design
were set by DOE (design of experiments). By changing the design parameters, such as the distribution of the blade loading,
spanwise circulation distribution and stacking, 32 different fan designs were created for the screening of parameters. The
overall performance and the local flow field of these fans were computed using a commercial CFD code. The results of the CFD
computations were analyzed by DOE. The pressure rise and efficiency were selected as the main responses, and the main effects
of the design parameters on the responses were discussed. The main design parameters for the optimum design of the fan were
decided from the results of the screening procedure. We designed the optimum axial fan by RSM (response surface method). The
design center fan was made by RP (rapid prototype) and the performance was tested using a fan tester based on AMCA standards.
These procedures ensured proper screening of parameters and optimum design of the axial fan.
This paper was presented at the 9th Asian International Conference on Fluid Machinery (AICFM9), Jeju, Korea, October 16–19, 2007. 相似文献
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模块化设计方法及其在机械设计中的应用 总被引:12,自引:0,他引:12
介绍了模块化设计产生的历史、模块和模块化设计的概念,分析了模块化的特征、作用与优点,阐述了模块划分的原则,并对模块化设计方式和模块化系统进行了分类,详细介绍了模块化设计的具体步骤,分析了模块化设计和现代技术之间的密切联系,并用数控立式车床的模块划分来举例说明了模块化设计方法在机械设计中的应用。 相似文献