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Direct stiffness method

About: Direct stiffness method is a research topic. Over the lifetime, 2584 publications have been published within this topic receiving 53131 citations.


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Journal ArticleDOI
TL;DR: In this article, a technique to evaluate the error propagation of the pseudodynamic testing of a nonlinear system is proposed, which mainly relies upon the introduction of the degree of nonlinearity to describe the variation of stiffness for each time step.
Abstract: A technique to evaluate the error propagation of the pseudodynamic testing of a nonlinear system is proposed. This technique mainly relies upon the introduction of the degree of nonlinearity to describe the variation of stiffness for each time step. The commonly used Newmark explicit method is chosen for this study and it is analytically proved that the upper stability limit is enlarged for the case of stiffness softening and is reduced for the case of stiffness hardening. These theoretical results are thoroughly confirmed with numerical examples. It is also theoretically and numerically verified that for each time step stiffness softening encounters less error propagation while stiffness hardening experiences more severe error propagation than for the stiffness invariant case. This is because stiffness softening results in the decrease of the natural frequency and the value of the degree of softening nonlinearity while stiffness hardening leads to the increase of the natural frequency and the value of the degree of hardening nonlinearity.

37 citations

Journal ArticleDOI
TL;DR: In this article, a method that estimates mass and stiffness matrices of shear building from modal test data is presented, which depends on only measurable points that are less in number than the total structural degrees of freedom, and on the first two orders of structural mode measured.
Abstract: A method that estimates mass and stiffness matrices of shear building from modal test data is presented in this paper. The method depends on only measurable points that are less in number than the total structural degrees of freedom, and on the first two orders of structural mode measured. So it is applicable to most of the general test. Based on this method modal data of unmeasurable points are estimated, then global mass and stiffness matrices of structure are obtained by using the first two orders of modal data. Taking advantage of iteration the optimum global mass and stiffness matrices are gained. Finally, an example is studied in this paper. Its result shows that this method is reliable. © 1998 John Wiley & Sons, Ltd.

37 citations

Journal ArticleDOI
TL;DR: In this article, the authors present a procedure for the automatic generation of symbolic stiffness matrices, which greatly reduces the amount of work involved in the construction of finite element stiffness matrix.
Abstract: Procedures for the automatic generation of symbolic stiffness matrices are presented that greatly reduce the amount of work involved in the construction of finite element stiffness matrices. The related system of programs is presented which completely automates the matrix generation and an example is given.

37 citations

Journal ArticleDOI
Tao Sun1, Hao Wu1, Binbin Lian1, Qi Yang1, Panfeng Wang1, Yimin Song1 
01 Dec 2017
TL;DR: In this article, a 5-degree-of-freedom hybrid manipulator as a friction stir welding robot is proposed, which is composed of a 3-degree of-freedom redundant parallel module and a 2-degrees of freedom rotating head, and an instantaneous stiffness performance index is proposed on the basis of instantaneous energy defined by reciprocal product of external payload screw and corresponding deformation screw.
Abstract: In order to meet the requirements of large downward force and high stiffness performance for the friction stir welding process, this paper proposes a 5 degree-of-freedom hybrid manipulator as friction stir welding robot. It is composed of a 3 degree-of-freedom redundant parallel module and a 2 degree-of-freedom rotating head. Semi-analytical stiffness model of the hybrid manipulator is firstly established by compliance models of the two substructures. Virtual work principle, deformation superposition principle and twist/wrench mapping model are applied to this compliance modeling process. A novel instantaneous stiffness performance index is then proposed on the basis of instantaneous energy defined by reciprocal product of external payload screw and corresponding deformation screw. It solves the problems of inconsistent physical unit of linear/angular stiffness and is able to evaluate overall and worst-case stiffness performance. Next, stiffness/compliance experiments are carried out to verify the stiffne...

37 citations

Journal ArticleDOI
TL;DR: In this paper, a comparative study was carried out to determine the accuracy of finite element analyses based on the stiffness method, a mixed method, and the new integrated force and dual integrated force methods.

37 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202334
202270
202123
202022
201930
201842