Sparks-Thomas Award - Recent Progresses in Physical Understanding, Mechanical Characterization and Modeling of the Mullins Softening in Carbon-Black Filled Rubbers

Carbon-black filled rubbers undergo substantial stress-softening and possible residual strain upon first stretch. This softening is known as the Mullins effect for Mullins’ significant contribution on the mechanical characterization, physical understanding and modelling of the phenomenon [1].  The presentation will review some recent progresses in: the mechanical characterization of the Mullins softening, defining an objective parameter to quantify the effect and a general criterion for its activation; the constitutive modelling, introducing damage directional constitutive equations reproducing induced anisotropy; and the physical understanding sorting out which of the physical damages may cause such a significant mechanical softening.

[1] Mullins, L., 1969. Softening of rubber by deformation. Rubber Chem. Technol. 42, 339-362.