Search results
Results from the WOW.Com Content Network
After developing the element stiffness matrix in the global coordinate system, they must be merged into a single “master” or “global” stiffness matrix. When merging these matrices together there are two rules that must be followed: compatibility of displacements and force equilibrium at each node.
The full stiffness matrix A is the sum of the element stiffness matrices. In particular, for basis functions that are only supported locally, the stiffness matrix is sparse. For many standard choices of basis functions, i.e. piecewise linear basis functions on triangles, there are simple formulas for the element stiffness matrices.
This type of element is suitable for modeling cables, braces, trusses, beams, stiffeners, grids and frames. Straight elements usually have two nodes, one at each end, while curved elements will need at least three nodes including the end-nodes. The elements are positioned at the centroidal axis of the actual members.
Physically, taking into account the added mechanisms of deformation effectively lowers the stiffness of the beam, while the result is a larger deflection under a static load and lower predicted eigenfrequencies for a given set of boundary conditions. The latter effect is more noticeable for higher frequencies as the wavelength becomes shorter ...
here is the mass matrix, is the damping matrix, and are internal force per unit displacement and external forces, respectively. Using the extended mean value theorem , the Newmark- β {\displaystyle \beta } method states that the first time derivative (velocity in the equation of motion ) can be solved as,
In the language of the finite element method, the matrix is precisely the stiffness matrix of the Hamiltonian in the piecewise linear element space, and the matrix is the mass matrix. In the language of linear algebra, the value ϵ {\displaystyle \epsilon } is an eigenvalue of the discretized Hamiltonian, and the vector c {\displaystyle c} is a ...
Macaulay's method has been generalized for Euler-Bernoulli beams with axial compression, [3] to Timoshenko beams, [4] to elastic foundations, [5] and to problems in which the bending and shear stiffness changes discontinuously in a beam. [6]
The finite element method has been the tool of choice since civil engineer Ray W. Clough in 1940 derived the stiffness matrix of a 3-node triangular finite element (and coined the name). The precursors of FEM were elements built-up from bars (Hrennikoff, Argyris, Turner) and a conceptual variation approach suggested by R. Courant.