Computational Methods for Solution of Inverse Problems in Mechanics最新文献

Regularization Matrices for Inverse Electrocardiography 逆心电图的正则化矩阵

Computational Methods for Solution of Inverse Problems in Mechanics Pub Date : 1998-11-15 DOI: 10.1115/imece1998-0223

L. Olson, R. Throne

引用次数: 0

Optimal Shape Design of Three Dimensional MEMS With Applications to Electrostatic Comb Drives 三维MEMS的最佳形状设计及其在静电梳状驱动器中的应用

Computational Methods for Solution of Inverse Problems in Mechanics Pub Date : 1998-11-15 DOI: 10.1115/imece1998-0217

W. Ye, S. Mukherjee

{"title":"Optimal Shape Design of Three Dimensional MEMS With Applications to Electrostatic Comb Drives","authors":"W. Ye, S. Mukherjee","doi":"10.1115/imece1998-0217","DOIUrl":"https://doi.org/10.1115/imece1998-0217","url":null,"abstract":"\u0000 A methodology for solving inverse problems in Micro-electromechanical (MEM) systems is proposed in this paper. Design of variable shape electrostatic comb drives (shape motors), in order to obtain desired force profiles, is presented as an application of the general methodology. This analysis includes simulation, sensitivity analysis and optimization.\u0000 A comb drive is one of the most important microactuators in MEM systems. In a standard comb drive, the capacitance varies linearly with displacement, resulting in an electrostatic driving force which is independent of the position of the moving fingers (relative to the fixed ones) except at the ends of the range of travel. It is of interest in some applications to have force profiles such as linear, quadratic or cubic. Such shaped comb drives could be useful, for example, for electrostatic tuning or to get actuators with longer ranges of travel than those of standard comb drives.\u0000 The present paper addresses the issues of simulation, sensitivity analysis, and then design (inverse problem) of comb drives with variable height profiles. Three-dimensional simulations of the exterior electrostatic field, and the resultant forces on the comb drive, are carried out with the exterior, indirect, boundary element method. Following direct simulation, sensitivity analysis is carried out by the direct differentiation approach. The variable of interest is the driving force while the design variables are parameters that determine the shape of the moving fingers. Next, an inverse problem is posed as follows: determine the height profile of the moving fingers such that the driving force is a desired function of the displacement of the comb drive. Comb drives of appropriate shapes, that produce desired force profiles, are obtained by this approach. Numerical results are given for shape motors that produce linear or cubic force profiles as functions of travel. The optimization code “E04UCF”, from the NAG package, is used for this phase of the work.","PeriodicalId":331326,"journal":{"name":"Computational Methods for Solution of Inverse Problems in Mechanics","volume":"64 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129960010","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Identification Problems for Vibrating Composite Plates 振动复合材料板的识别问题

Computational Methods for Solution of Inverse Problems in Mechanics Pub Date : 1998-11-15 DOI: 10.1115/imece1998-0224

S. Abrate, M. Perry

引用次数: 0

Identification of the Friction Coefficient for Steady and Unsteady Shallow-Water Flows 定常与非定常浅水流动摩擦系数的辨识

Computational Methods for Solution of Inverse Problems in Mechanics Pub Date : 1998-11-15 DOI: 10.1115/imece1998-0220

A. Soulaimani

引用次数: 0

Estimation of Distributions of Contact Stressess and Displacements Using Regularization Schemes 用正则化方法估计接触应力和位移的分布

Computational Methods for Solution of Inverse Problems in Mechanics Pub Date : 1998-11-15 DOI: 10.1115/imece1998-0219

S. Kubo, K. Ohji

{"title":"Estimation of Distributions of Contact Stressess and Displacements Using Regularization Schemes","authors":"S. Kubo, K. Ohji","doi":"10.1115/imece1998-0219","DOIUrl":"https://doi.org/10.1115/imece1998-0219","url":null,"abstract":"\u0000 Estimation of tractions and displacements on inaccessible boundaries, such as contact areas of solids, can be regarded as an inverse boundary value problem. In this study finite-element based inverse analysis schemes with regularization were applied to the estimation of the distributions of tractions and displacements on contact areas. The finite element equation was rewritten in terms of unknown boundary values on the contact area using over-prescribed boundary values. This equation was solved for the boundary values on the contact area. Like many other inverse problems, this inverse problem was severely ill-conditioned and the estimated distributions were very sensitive to the over-prescribed boundary values used in the estimation. To overcome the ill-posedness of this boundary value inverse problem, the function expansion method and Tikhonov regularization were introduced in the finite element-based inverse analysis scheme. The number of terms in the function expansion and the smoothing parameter in Tikhonov regularization were regarded as regularization parameters in the inverse analysis. To determine the optimum value of these regularization parameters, the estimated error criterion and the AIC were introduced. The usefulness of the finite element-based inversion scheme was examined by numerical simulations. It was found that the distributions of tractions and displacements can be estimated reasonably even from noisy observations by using the finite-element based inverse analysis schemes with regularization. The optimum value of the regularization parameters can be estimated by the estimated error criterion or by the AIC.","PeriodicalId":331326,"journal":{"name":"Computational Methods for Solution of Inverse Problems in Mechanics","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133597988","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A Flexibility-Based Inverse Algorithm for Identification of Substructural and Joint Properties 一种基于柔性的子结构和关节特性逆识别算法

Computational Methods for Solution of Inverse Problems in Mechanics Pub Date : 1998-11-15 DOI: 10.1115/imece1998-0216

K. Park, C. Felippa

{"title":"A Flexibility-Based Inverse Algorithm for Identification of Substructural and Joint Properties","authors":"K. Park, C. Felippa","doi":"10.1115/imece1998-0216","DOIUrl":"https://doi.org/10.1115/imece1998-0216","url":null,"abstract":"\u0000 This paper presents an inverse problem methodology for the identification of structural joint characteristics. The underlying theory employs a substructural flexibility method that allows statistical uncertainties in joints and interfaces. The method partitions structures into continuum and localized joint/interface substructural regions. The former are modeled by continuum finite elements and built up with the standard direct-stiffness method. Joint and interface regions are constructed from continuum and/or special elements. The novel aspect of the method is that the coupling of substructures is effected in terms of node-collocated Lagrange multipliers, which leads naturally to a boundary-flexibility formulation. Coupling through interaction forces addresses the concern that delicate localized effects are not masked out in the overall structural model. This heightened sensitivity is significant for inverse problems in which localized properties and uncertainties are deduced indirectly, through a hierarchical “peeling off” process. The method is applied to identify joint flexibilities in a model engine mount, which demonstrates key features of the method and its high-fidelity capability.","PeriodicalId":331326,"journal":{"name":"Computational Methods for Solution of Inverse Problems in Mechanics","volume":"106 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114630052","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 3