Topic
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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TL;DR: An exact dynamic stiffness method is developed for predicting the free vibration characteristics of a three-beam system, which is composed of three non-identical uniform uniform beams of equal length connected by innumerable coupling springs and dashpots as discussed by the authors.
21 citations
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TL;DR: In this article, two methods for identifying the mass, damping and stiffness matrices of a linear vibrating system are presented, which require the measurement of acceleration, velocity and displacement at various locations of the system.
Abstract: Two methods for identifying the mass, damping and stiffness matrices of a linear vibrating system are presented. Both methods require the measurement of acceleration, velocity and displacement at various locations of the system. In the first method, the response of the system subjected to known forces is used while the second method employs the free vibration data. The unknown parameters are recovered through the standard least squares procedure. Numerical results are presented for several examples.
21 citations
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TL;DR: In this paper, the eigenvalues or natural frequencies of the global stiffness matrix offer a decision basis regarding the damage-induced change of structural features, which is a common feature of these processes.
Abstract: For more than 50 years, the technology of linear damage processes has been known and mastered. Strong, progressive damage processes have recently been discovered on various types of structures, for which a uniform theory has been unavailable. A common feature of these processes is the wide-band excitation of the dominant forces (ocean waves, storm, traffic), a shift of the structural response spectrum into domains of higher excitation caused by degrading structural stiffness, as well as a damage-controlled self-adaptation phenomenon. Any numerical investigation of progressive damage phenomena should be based on the load- or time-evolution of the global stiffness matrix. The eigenvalues or natural frequencies of this stiffness matrix offer a decision basis regarding the damage-induced change of structural features.
21 citations
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TL;DR: In this paper, a computational procedure for extracting substructure-by-substructure flexibility properties from global modal parameters is presented, which is based on an element-based direct flexibility method.
Abstract: A computational procedure for extracting substructure-by-substructure flexibility properties from global modal parameters is presented. The present procedure consists of two key features: an element-based direct flexibility method which uniquely determines the global flexibility without resorting to case-dependent redundancy selections; and, the projection of cinematically inadmissible modes that are contained in the iterated substructural matrices. The direct flexibility method is used as the basis of an inverse problem, whose goal is to determine substructural flexibilities given the global flexibility, geometrically-determined substructural rigid-body modes, and the local-to-global assembly operators. The resulting procedure, given accurate global flexibility, extracts the exact element-by-element substructural flexibilities for determinate structures. For indeterminate structures, the accuracy depends on the iteration tolerance limits. The procedure is illustrated using both simple and complex numerical examples, and appears to be effective for structural applications such as damage localization and finite element model reconciliation.
21 citations
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TL;DR: The development of closed-form stiffness matrices is extended to the next level of approximation, the subparametric p-level 4 element, and it is found that the compilers used could better optimize the code with closed form generated expressions for efficient execution when compared to the code for numerical integration.
21 citations