Flat-ended rebound indentation test for assessing viability of articular   cartilage: Application of the viscoelastic layer model
  The rebound indentation test consisting of the displacement-controlled and load-controlled stages is considered for a frictionless cylindrical flat-ended indenter. The mechanical behavior of an articular cartilage layer sample is modeled in the framework of viscoelastic model with time-independent Poisson's ratio. Closed-form analytical expressions for the contact force (in the displacement controlled stage) and for the indentation displacement (in the load-controlled stage) are presented for an arbitrary viscoelastic solid model. The case of standard viscoelastic solid model is considered in detail. It has been established that the rebound displacement (that is the indentation displacement in the load-controlled stage) does not depend on the relaxed elastic modulus and Poisson's ratio as well as on the layer's thickness. 
I. Argatov, G. Mishuris
physics.bio-ph