Hi Hu Jingqiao,

A tie constraint joins together two regions with whose meshes may be dissimilar. If the meshes are similar and the nodes are coincident then merging the nodes is the best option and it will give the same results at a lower computation cost.

When two regions are tied together, there will be no relative motion between them. In other words, they become one on all the active degree of freedoms.

The tie is treated based on the "Discretization method" as described in Abaqus manual. By default "surface-to-surface" is used for Abaqus/Standard and "node-to-surface" for Abaqus/Explicit. However, you can still select the discretization method that best describe your model.

Select "Node-to-surface" to generate the tie coefficients according to the interpolation functions at the point where the slave node projects onto the master surface.

Select "Surface-to-surface" to generate the tie coefficients such that stress accuracy is "optimized" for the specified surface pairing.

Regards.

Thanks for your reply, Hamza Sulayman Abdullahi .

BTW, If anyone is interested, I have found FEM explanation of Tied interface in the Chapter. 8 of the book

Zienkiewicz O C, Taylor R L. The finite element method for solid and structural mechanics[M]. Elsevier, 2005.

Good question