I'm simulating the interface between a steel plate and the fire proof coatings covering the steel plate. The elements i use in the simulation is contact 173 with a material property of debonding,which is defined as cohesive zone model.(CZM)

 CZM in ansys provides  TBDATA such as maximum contact stress,contact at the completion of debonding, but what's the problem is that I failed to set the initial contact stiffness. it's true that ansys provides FKN to define the contact stiffness, but it's just a stiffness factor.