March 26, 2021 at 12:00 pm

peteroznewman

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nThere are more Gauss points in a quadratic element that in a Linear element.nWhen assembling the stiffness matrix, the displacements are unknown. They appear as a variable in the equation, along with all the constants for terms such as Young's modulus. The equations use the location of the Gauss point within each element as a place to do the integration required to have equilibrium in the solution.nDuring solving, only the unknown displacements are solved for. Stress and strain are not solved for, but the equations that have stress and strain terms in them were included during the assembly phase of the stiffness matrix, before the solving started.nAfter the system of equations is solved, the displacements become known and now values can be put into equations to extract out values of stress and strain.nIt is a three step process. 1. Assemble the stiffness matrix. 2. Solve for the unknown displacements. 3. Postprocess solved displacements to get stress and strain. n