Models of nonlinear kinematic hardening based on different versions of rate-independent maxwell fluid

Different models of finite strain plasticity with a nonlinear kinematic hardening are analyzed in a systematic way. All the models are based on a certain formulation of a rate-independent Maxwell fluid, which is used to render the evolution of backstresses. The properties of each material model are determined by the underlying formulation of the Maxwell fluid. The analyzed approaches include the multiplicative hyperelastoplasticity, additive hypoelasto-plasticity and the use of generalized strain measures. The models are compared with respect to different classification criteria, such as the objectivity, thermodynamic consistency, pure volumetric-isochoric split, shear stress oscillation, exact integrability, and w-invariance

Extended concept of representative directions to describe inelastic behaviour of electrospun polymers

The concept of representative directions allows one to generalize onedimensional uniaxial material models to more general constitutive equations, suitable for arbitrary multi-axial loading scenarios. The procedure preserves the thermodynamic consistency and the resulting material model satisfies the principle of objectivity. In the current paper, the concept is modified by the introduction of new kinematics. Some features of the resulting constitutive equations as well as the applicability of the extended concept to real materials are discussed. For demonstration purposes, the plastic behaviour of an electrospun polymer is modelled under large strain non-monotonic loading

Steady-State Creep Analysis of Pressurized Pipe Weldments by Perturbation Method

The stress analysis of pressurized circumferential pipe weldments under steady state creep is considered. The creep response of the material is governed by Norton's law. Numerical and analytical solutions are obtained by means of perturbation method, the unperturbed solution corresponds to the stress field in a homogeneous pipe. The correction terms are treated as stresses defined with the help of an auxiliary linear elastic problem. Exact expressions for jumps of hoop and radial stresses at the interface are obtained. The proposed technique essentially simplifies parametric analysis of multi-material components.Comment: 17 pages, 6 figure