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: In this paper, a new method for structural damage identification based on flexibility disassembly is presented, which decomposes a structural flexibility matrix into a matrix representation of the connectivity between degrees-of-freedom and a diagonal matrix containing the magnitude information.
Abstract: This paper presented a new method for structural damage identification based on flexibility disassembly. The basic idea of the developed theory is to decompose a structural flexibility matrix into a matrix representation of the connectivity between degrees-of-freedom and a diagonal matrix containing the magnitude information. Using the flexibility disassembly, a new damage detection scheme is presented to approach the damage identification problem in three steps. The scheme has a unique advantage that it can accurately compute the stiffness perturbation parameter without any higher-order sensitivity analysis or iteration. The efficiency of the proposed method is demonstrated by five numerical examples.
48 citations
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TL;DR: In this paper, an elastic model of a soft-finger contact is proposed and a generalized contact stiffness matrix is developed by applying the congruence transformation and by introducing stiffness mapping of the line springs in translational directions and rotational axes.
Abstract: This paper investigates the soft-finger contact by presenting the contact with a set of line springs based on screw theory, reveals the rotational effects, and identifies the stiffness properties of the contact. An elastic model of a soft-finger contact is proposed and a generalized contact stiffness matrix is developed by applying the congruence transformation and by introducing stiffness mapping of the line springs in translational directions and rotational axes. The effective stiffnesses along these directions and axes are hence obtained and the rotational stiffnesses are revealed. This helps create a screw representation of a six-dimensional soft-finger contact and produce an approach of analyzing and synthesizing a robotic grasp without resorting to the point contact representation. The correlation between the rotational stiffness, the number of equivalent point contacts and the number of equivalent contours is given and the stiffness synthesis is presented with both modular and direct approaches. The grasp thus achieved from the stiffness analysis contributes to both translational and rotational restraint and the stiffness matrix so developed is proven to be symmetric and positive definite. Case studies are presented with a two-soft-finger grasp and a three-soft-finger grasp. The grasps are analyzed with a general stiffness matrix which is used to control the fine displacements of a grasped object by changing the preload on the contact.
48 citations
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TL;DR: In this article, a non-dimensional formulation is adopted, and the frequency dependent trigonometric shape functions are used to find a simple frequency dependent element stiffness matrix which has both mass and stiffness properties.
47 citations
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TL;DR: In this article, a geometrically non-linear formulation that preserves higher-order terms in the strain energy function is proposed. But the formulation does not consider the axial and transverse displacements in the motion equation.
47 citations