IC MAGE M35 is a user-defined model for PLAXIS built using the IC MAGE UMIP framework which uses a hypoelastic formulation to simulate the non-linear stiffness of prop elements, which can be affected by slack in various components of the system. The envisaged modelling approach requires the explicit modelling of the prop using solid elements to which this material model must be assigned. Starting with no stiffness, the model uses an hyperbolic law, with the stiffness value increasing asymptotically to its theoretical value.
Taborda et al. (Tue,) studied this question.