Smoothed contact in a micromechanical model for cement bound materials

The stability of a micromechanical constitutive model with embedded rough contact is considered. Spurious contact chatter at the constitutive level is reported. A single smooth contact state function-which employs two interpolation functions at contact state boundaries-is proposed to replace three existing discrete contact functions. Following a parametric study, values are assigned to three smoothing parameters that control the shape of the interpolation functions. The contact related instability is efficiently removed without unrealistic alteration of the predicted response. The smoothed contact formulation is then introduced in a constitutive model and its performance assessed in a series of 2D and 3D simulations.