ABSTRACT

New User-Supplied Subroutines in DIANA have been proposed for the elastic matrix of rubberlike materials in this paper. When the first and second derivatives of the strain energy function are known, other information can be generated automatically in DIANA through the new User-Supplied Subroutines. Knowles’ and Gao’s constitutive laws for rubber-like materials have been implemented in DIANA by this means. Singular problems are described successfully by those constitutive laws. We demonstrate two representative examples: uniaxial and biaxial tension analyses of a rubber cube show that the DIANA finite element package provides data which are consistent with the analytical results. When a new strain energy function is proposed in the future, the new constitutive law could be more conveniently inserted into DIANA than before. The new User-Supplied Subroutines in DIANA render new possibilities to study mechanics of rubber-like materials.