Question

Which option is not correct about the three-noded triangular plane stress (linear) element used in FEM?

(a) It has six degrees of freedom

(b) It belongs to both the isoparametric and superparametric element families

(c) It can be improved by the addition of internal degrees of freedom

(d) Delaunay triangulation can be used for its mesh generation

This question was posed to me during an interview for a job.

I would like to ask this question from Library of Elements and Interpolation Functions topic in chapter Interpolation Functions, Numerical Integration and Modelling Considerations of Finite Element Method

Answer 1

Right answer is (c) It can be improved by the addition of internal degrees of freedom

The explanation: The three-node triangular element with linear displacements for the plane stress problem is simply called a linear triangle. It has six degrees of freedom and it belongs to both the isoparametric and superparametric element families. A mesh of linear trianglecan be easily generated using Delaunay triangulation, but the element cannot be improved by the addition of internal degrees of freedom; rather, it can be improved by increasing the number of nodes.