Aspects of constitutive modeling in continuum-kinematics-inspired peridynamics

Continuum-kinematics-inspired Peridynamics (CPD) has been recently proposed as a geometrically exact formulation of peridynamics (PD) that is also thermo- dynamically and variationally consistent. Unlike the original formulation of PD, CPD can accurately capture the Poisson effect. CPD consists of one-, two- and three-neighbor interactions. The isotropic CPD formulation of non-local elasticity therefore involves three material constants associated with length, area and volume. This manuscript aims to establish the relationships between the material parameters of CPD and isotropic linear elasticity for two- and three-dimensional problems. Two alternatives for the CPD energy density are introduced. Analytical solutions of the energy densities for affine deformations are derived. It is shown that the three material parameters of CPD reduce to two independent pa- rameters in the linearized framework, and can be expressed in terms of any pairs of isotropic linear elasticity constants, such as Lame parameters. The analysis here provides a physical interpretation for the first Lame constant. Finally, the admissible ranges for CPD material parameters are established.