I have an update on this topic. To create a submodel of clinched joint which is to be used in a bigger structure, the best recommended method is by using spring connection. One spring required in each direction having stiffness values derived from experimental results of single point clinched joint for shear and tensile tests. There should be two remote points along each axis, 0,05 mm away from the center (co-ordinate origin) in positive and negative direction. These will be the connecting point for the springs. The pinball diameter can be set equal to the diameter of clinched joint.

The calculation of stiffness values obtained from experimental results needs to be as accurate as possible i.e. the selection of force and displacement values. 

The major challenge here is to define the failure criteria.