Question

Which nodes of the higher-order elements of the Lagrange family do not contribute to the inter-element connectivity?

(a) Interior nodes

(b) All nodes

(c) Corner nodes

(d) Intermediate nodes

This question was addressed to me by my school teacher while I was bunking the class.

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

Correct answer is (a) Interior nodes

To explain I would say: Since the Interior nodes of the higher-order elements of the Lagrange family do not contribute to the inter-element connectivity, they can be condensed out at the element level so that the size of the element matrices is reduced. The elements formed after removing the Interior nodes are called serendipity elements.