Interface stresses

Question

Hi, 
 
 In the table output of interface stresses there are two options 'node values' and 'stress point values'. Which one should be used to extract stresses? 
 Do interface has stress points as well? 
 The status of the points show failure or failure*. what is the significance of the '*'? 
 What is the difference between 'node' and 'wall node'?

Vasileios Basas · Answer

Hi Debasmita, 
 Answering your second question, the stiffness matrix for interface elements is obtained by means of Newton Cotes integration. The position of the Newton Cotes stress points coincides with the node pairs (see Section 5.6.6.2 Interface elements on PLAXIS 2D - Reference manual). Also, stresses in an element are calculated at the stress points (Gauss points) and then extrapolated to the nodes. However, the quality of this process can depend on many things (e.g. element size, order of element, etc.) and thus may introduce an extrapolation error. Therefore, it is best to consider stresses at stress points as more accurate. However, I believe the results for interfaces are given only on nodal points. For your other questions, please refer to this forum post: communities.bentley.com/.../717583