Theoretical analysis of strain response envelopes using incrementally non-linear constitutive equations

This paper reviews some incrementally non-linear constitutive equations of interpolation type, and proposes a new approach to illustrate the discrepancies between different interpolation models. This approach uses the strain response envelopes, based on experimental data when restricted to triaxial plane, and the Jacobian of the constitutive equations to examine the loss of uniqueness. A new family of interpolation functions is proposed to meet the three requirements: ? 1 -continuity of strain response envelope, correct description of experimental data, and respect of the one-to-one property.