THE LOSS AND RECOVERY OF STRESS ACCURACY IN FEM AS SEEN FROM MATRIX DISPLACEMENT METHOD

In the matrix displacement method, a “fixed end force” term is added for computing the member end forces, while in the finite element method (FEM) the nodal stresses are calculated directly from the derivatives of the element displacements without including the fixed end force term. This has been found to be a major source of the stress accuracy loss in FEM. For one dimensional problems, however, a similar “fixed end force” term can also be added in FEM, resulting super convergent nodal stresses that ...