共查询到20条相似文献,搜索用时 15 毫秒
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将热权函数法拓展为包括温度载荷、表面力和体积力等机械载荷在内的通用权函数法.通用权函数只与物体的几何形状有关,与时间及载荷无关.利用多虚拟裂纹扩展技术,给出热和机械载荷联合作用下的三维Ⅰ型裂纹问题通用权函数法的有限元格式.通用权函数法特别适合于计算复杂冲击载荷下应力强度因子分布的过渡过程.计算实例表明,通用权函数法具有很高的计算效率,又具有与COD法相当的精度. 相似文献
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Chae Ho Kim Seock Sam Kim Young Jae Shin 《Journal of Mechanical Science and Technology》1990,4(2):136-140
This paper presents a new solution method for the analysis of multibody systems with Coulomb friction. Complete equations
of motion and reaction forces are derived by using Lagrangian formulation and the traditional friction circle concepts for
the analysis of Coulomb friction. The numerical solutions by the new method, as well as the conventional method for comparision,
are illustrated. The new method saves considerably the computer execution time to solve equations of motion and reaction forces
compared with the conventional method for same accuracy. The higher the coefficient of friction is, the more the computation
time of the conventional method is needed but the computation time of the new method is nearly independent on the coefficient
of friction. 相似文献
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给出了任意凸多面体声腔在内部点源和外力激励下,腔内声压分布的解析解。该解析方法较传统的数值方法,不仅数据准备量小、速度快精度高,且能够解决目前常用的声弹性法难以解决的复杂几何形状的封闭空腔的声固耦合问题。在此基础上,结合有源结构声控制方法,建立了复杂封闭空间局部区域有源消声的模型,给出了矩阵形式的数值算法,并对一类似车辆驾驶室的复杂封闭空腔进行了有源降噪仿真分析,降噪效果良好,证明该方法可以作为复杂封闭空间有源力消声控制系统的建模基础。 相似文献
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LIU Deshun YUE Wenhui ZHU Pingyu Hunan Provincial Key Laboratory of Health Maintenance for Mechanical Equipment Hunan University of Science Technology Xiangtan China DU Xiaoping Department of Mechanical Aerospace Engineering University of Missouri-Rolla Rolla M USA 《机械工程学报(英文版)》2006,19(4):514-518
Conventional reliability-based design optimization (RBDO) requires to use the most probable point (MPP) method for a probabilistic analysis of the reliability constraints. A new approach is presented, called as the minimum error point (MEP) method or the MEP based method, for reliability-based design optimization, whose idea is to minimize the error produced by approximating performance functions. The MEP based method uses the first order Taylor's expansion at MEP instead of MPP. Examples demonstrate that the MEP based design optimization can ensure product reliability at the required level, which is very imperative for many important engineering systems. The MEP based reliability design optimization method is feasible and is considered as an alternative for solving reliability design optimization problems. The MEP based method is more robust than the commonly used MPP based method for some irregular performance functions. 相似文献
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对数正态分布的最好线性无偏估计方法是工程中常用方法,但是目前只能用于样本量不超过20个的情况。通过将无穷区间内积分,变换为有限区间内积分,以及采用高效的自适应高斯积分方法,解决了次序统计量的均值和方差的快速计算问题,从而将对数正态分布最好线性无偏估计方法,推广到样本量为40个以上情况,为可靠性数据分析,提供了高精度的计算方法。 相似文献
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用基础的测量方法和数据处理方法对直线度误差进行评定。测量方法采用水平仪的节距法。数据处理方法采用两端点连线法、最小二乘法、最小区域法。每一种方法都分别用计算法和作图法评定直线度误差。采用不同的方法对同一组数据评定直线度误差,其结果不尽相同,并对其精度进行比较,从而得出应用这三种方法评定直线度误差的差别。 相似文献
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The solution of tension distributions is infinite for cable-driven parallel manipulators(CDPMs) with redundant cables. A rapid optimization method for determining the optimal tension distribution is presented. The new optimization method is primarily based on the geometry properties of a polyhedron and convex analysis. The computational efficiency of the optimization method is improved by the designed projection algorithm, and a fast algorithm is proposed to determine which two of the lines are intersected at the optimal point. Moreover, a method for avoiding the operating point on the lower tension limit is developed. Simulation experiments are implemented on a six degree-of-freedom(6-DOF) CDPM with eight cables, and the results indicate that the new method is one order of magnitude faster than the standard simplex method.The optimal distribution of tension distribution is thus rapidly established on real-time by the proposed method. 相似文献
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A study on numerical solution method for efficient dynamic analysis of constrained multibody systems
Jae-Hwan Lim Hong Jae Yim Si-Hyung Lim Taewon Park 《Journal of Mechanical Science and Technology》2008,22(4):714-721
A new and efficient computational method for constrained multibody systems is proposed. In the proposed method, local parametrization
method is employed to apply the same solution method for position, velocity, and acceleration analyses since the coefficient
matrices for each analysis have an identical matrix pattern. The skyline solution method is used to overcome numerical inefficiency
when solving large scaled equations. Also, subsystem mpartitioning method is derived systematically to perform parallel processing
for real time simulation. To show the numerical accuracy and efficiency of the proposed method, three numerical problems are
solved. 相似文献
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This paper treats a solution for the ill-posed (inverse) load determination problem for a time-varying load on a beam. The
ill-posed nature of the problem causes numerical instability. Conventional numerical approach for solutions results in arbitrarily
large errors in solution. The Tikhonov regularization method, which is a non-iterative stabilization technique, has been widely
adopted for overcoming the ill-posed nature (or numerical instability). However, in this paper, we introduce an “iterative”
regularization method, specifically, the iterated Tikhonov regularization method. The iterated method is applied to the present
load determination problem. The result of the iterative method is compared with that of the (non-iterative) Tikhonov regularization.
The rate of convergence for the introduced iterative method turned out to be very fast. The accuracy and applicability of
the introduced method are examined through a numerical experiment. 相似文献
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J.E. Zúñiga-JuárezJ.A. Reynoso-Hernández J.R. Loo-Yau M.C. Maya-Sánchez 《Measurement》2011,44(9):1491-1498
An improved two-tier L-L method for characterizing symmetrical microwave test fixtures is introduced in this paper. The improved two-tier L-L method is implemented with two uniform transmission lines having the same characteristic impedance and propagation constants, but different lengths. The ABCD parameters of the test fixture and the embedded device under test (DUT) can be determined by measurements of the two lines and the DUT. To validate the improved L-L method, the two-tier thru-reflect-line (TRL) calibration technique is used. High correlation between the S-parameter data de-embedded with the TRL and with the proposed two-tier L-L validates the method. Moreover, the improved L-L method is not only useful for characterizing the test fixture, but is also useful for determining the line characteristic impedance. The main advantage of the two-tier L-L method over the two-tier TRL is the number of calibration elements. The former method uses two and the latter method uses three. 相似文献
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ZHANG Guoyu SUN Tianxiang WANG Lingyun XU Xiping School of Photo-electronic Engineering Changchun University of Science Technology Changchun China 《机械工程学报(英文版)》2007,20(2):101-103
The system mathematical model of flexible 3D measuring system is built by theoretical analysis,and the theoretical formula for measuring space point coordinate is also derived. Frog-jumping based coordinate transform method is put forward in order to solve measuring problem for large size parts. The frog-jumping method is discussed,and the coordinate transform mathematical model is method of the space point coordinate compared to original value,and an advanced method is provided. Form the space point coordinate transform formula can derive the calculation measuring method for measuring large size parts. 相似文献
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直接设计方法是一种先进的换热器设计方法,当换热器的局部几何特征可以代表整体的几何特征时,便可以应用此方法。此方法从有规律的换热器局部几何特征出发,通过计算以及推导确定换热器壳程、管程的允许压力损失以及总的传热量限制条件下管长对管数的关系式,将三个关系式绘制于同一图中来确定设计区域,从而进行后续的设计计算。本文运用此方法,对螺旋折流式换热器进行了简单的设计。 相似文献
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沟曲率半径系数是轴承设计中一个重要的设计参数,对轴承的承载能力和疲劳寿命有较大影响。目前为止,特大型四点接触球轴承沟曲率半径系数的设计依靠经验取值,缺乏设计依据,由此设计出来的轴承不能保证满足承载能力的要求。给出了特大型四点接触球轴承精确静承载曲线的绘制方法,提出了根据特大型四点接触球轴承精确静承载曲线设计轴承沟曲率半径系数的方法并给出了相应的设计流程,同时还给出了此类轴承疲劳寿命的计算方法。给出的沟曲率半径系数设计方法能够精确设计特大型四点接触球轴承的沟曲率半径系数,设计出的轴承一定满足轴承承载能力的要求及较高疲劳寿命的要求。此外,该设计方法可提高轴承的设计效率,并为轴承沟曲率半径系数设计方法的发展提供理论基础。 相似文献
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The simulation method of the fretting wear prediction using boundary element method is developed. The contact pressure and the contact width which is the first step to predict fretting wear are obtained from contact analysis of a semi-infinite solid based on the use of influence functions and patch solutions. The geometrical updating is based on nodal wear depths computed using Archard’s equation for sliding wear. The prediction of fretting wear for two cases of contact problems is performed; one is two-dimensional cylinder on flat contact which is for the comparison with a previous model by finite element method; the other is three-dimensional spherical contact. It is observed that for two-dimensional cylindrical contact the boundary element method developed in this study reduced the calculation time by 1/48 compared to FE method. We also showed the use of developed simulation technique is efficient to predict the fretting wear for three-dimensional spherical contact. 相似文献
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研究了FTA可靠性分析方法用于通信设备故障诊断的问题.介绍了故障树表达通信设备故障根因的概念和基于FTA方法进行故障分析和故障诊断的方法.最后结合光传输设备常见的RLOS故障告警实例,对FTA技术在故障自动诊断中应用进行了验证.所研究和分析的方法结合实际场景,简捷有效,方便工程人员使用. 相似文献