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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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TL;DR: In this paper, a finite element scheme for the analysis of instability phenomena of arbitrary thin shells is described, and a computationally efficient procedure is proposed for calculating the non-linear stiffness and tangential stiffness matrices for a doubly-curved quadrilateral element defined by co-ordinate lines.
Abstract: This paper describes a new finite element scheme for the analysis of instability phenomena of arbitrary thin shells. A computationally efficient procedure is proposed for calculating the non-linear stiffness and tangential stiffness matrices for a doubly-curved quadrilateral element defined by co-ordinate lines. The essential feature is the explicit addition of the non-linear terms into the rigid-body motion of the element. Thus the non-linear and tangential element stiffness matrices can easily be generated by transforming the generalized element stiffness matrix for linear analysis, and the non-linear terms of these matrices are separated into a number of component terms multiplied by the rigid-body rotations. These component terms can be stored permanently and used to calculate efficiently the non-linear and tangential stiffness matrices at each iteration. Illustrative examples are presented which confirm the validity of the present approach in the analysis of instability phenomena of thin plates and shells.
32 citations
TL;DR: In this article, a manufacturing complexity index is proposed to assess manufacturing complexity without undertaking a detailed cost analysis, which interprets numerically qualitative issues such as simple and complex layups.
Abstract: Design criteria are essential for describing the objectives of optimization. Strength, stiffness, and manufacturing are addressed.The mechanical criteria, for strength and stiffness, provide with the magnitude by which the thickness of a given laminate must be scaled in order to just meet all requirements. For first-ply-failure strength, a quartic failure criterion was derived from the quadratic Tsai-Wu criterion, for unsymmetric and symmetric laminates subject to mixed loadsets. For stiffness, maximum displacement constraints can be selectively set on all components and modulus. Combined strength and stiffness control is also analyzed. While developed for single elements, these criteria are also suited for designing entire laminated plates.Assessing manufacturing complexity without undertaking a detailed cost analysis is achieved by an index which interprets numerically qualitative issues such as simple and complex layups. The new manufacturing complexity index takes into account variations in thickness,...
32 citations
TL;DR: In this article, the elastodynamics of Spherical parallel robots are described through an exact dynamic model, where Timoshenko arches are used to simulate flexible curved links while the base and mobile platforms are modelled as rigid bodies.
32 citations
TL;DR: In this article, a stiffness reduction method for the in-plane design of steel frames is presented, which reduces the flexural stiffnesses (EI) of the members of a steel frame by considering the first-order forces they are subjected to through the stiffness reduction functions and performing Geometrically Nonlinear Analysis (i.e. second-order elastic analysis).
32 citations
TL;DR: In this article, a method for the formation of the stiffness matrix of a rectangular plate finite element with a non-propagating, one-edge, open crack is presented.
32 citations