You can use node-to-node contact elements to model point-to-point contact (flexible-flexible or rigid-flexible). Additionally, you can use these elements to represent contact between two surfaces by specifying individual node-to-node contact between the opposing nodes of each surface. This use requires that the nodes of the two opposing surfaces match up geometrically and that the relative sliding between the two surfaces is negligible. In addition, the deflections (rotations) of the two surfaces must remain small.