A constitutive model for compressible elastomeric solids

A non-linear thermo-elastic constitutive model for the large deformations of isotropic materials is formulated. This model is specialized to account for the physics and thermodynamics of the elastic deformation of rubber-like materials, and based on these molecular considerations a constitutive model for compressible elastomeric solids is proposed. The new constitutive model generalizes the incompressible and isothermal model of Arruda and Boyce (1993) to include the compressibility and thermal expansion of these materials. The model is fit to existing experimental data on vulcanized natural rubbers to determine the material parameters for the rubbers examined. The fit between the simple model and the data is found to be very good for large stretches and moderate volume changes.List of symbols xs=f(p) Deformation function - p Material point of a body in a reference configuration - x Place occupied by material point p in the current configuration - F(p)eq(t6/t6p) f(p) Deformation gradient - Js=det Fs>0 Determinant of F - Fs=RUs=VR Polar decompositions of F - U, V Right and left stretch tensors; positive definite and symmetric - R Rotation tensor; proper orthogonal - U=_1–1³₁²r₁r₁ Spectral representation of U - V=₁₌₁³_t²1_t1₁ Spectral representation of V - _t > 0 Principal stretches - {r_i} Right principal basis - {l_i} Left principal basis - Cs=F^TF, Bs=FF^T Right and left Cauchy-Green strain tensors - gqs>0 Absolute temperature - ge Internal energy density/unit reference volume - gh Entropy density/unit reference volume - gys=get-gqgh Helmholtz free energy/unit reference volume