The role of configurational stress in yield and plastic flow is discussed for a macroscopic model of rate-independent, finite-strain plasticity. The model is based on the traditional elastic-plastic decomposition of the deformation gradient, on integral balance laws and on thermodynamically restricted, rate-independent constitutive relations. Its formulation emphasizes the intermediate configuration in both the development of constitutive relations and the expression of balance laws. In addition to the usual balance laws, a couple balance is included to represent the action of plastic couples in the intermediate configuration. In particular, it is shown that the internal couple decomposes into a non-dissipative configurational stress and a dissipative couple that resists plastic flow. The couple balance thus determines a relation between the configurational stress and the plastic-flow resistance, a relation that can be interpreted as a generalized yield condition. A dissipation function is introduced and a maximum-dissipation criterion is used to obtain additional constitutive restrictions, which lead to a counterpart in the intermediate configuration of the classical normality conditions. The versatility of the framework is illustrated by applying it to rigid-plastic flow, in which case a nonlinear generalization of the classical Lévy-von Mises theory is obtained.

The occurrence of striped domains in stretched nematic elastomers has been suggested as evidence for soft elasticity. Conversely, the neo-classical model of Bladon, Terentjev and Warner, which displays soft elasticity, predicts striping. Here we show that the postulated director rotations and shears in the domain regions are also predicted by more general constitutive models that do not involve any notion of softness. Striping in nematic elastomers may therefore be a more general phenomena that is not necessarily an indication of soft elasticity. Furthermore, constitutive models more general than the neo-classical model may also explain the behavior of some nematic elastomers that do not appear to exhibit striping.

A continuum model of crystalline solid equilibrium is presented in which the underlying periodic lattice structure is taken explicitly into account. This model also allows for both point and line defects in the bulk of the lattice and at interfaces, and the kinematics of such defects is discussed in some detail. A Gibbsian variational argument is used to derive the necessary bulk and interfacial conditions for multi-phase equilibrium (crystal-crystal and crystal-melt) where the allowed lattice variations involve the creation and transport of defects in the bulk and at the phase interface. An interfacial energy, assumed to depend on the interfacial dislocation density and the orientation of the interface with respect to the lattices of both phases, is also included in the analysis. Previous equilibrium results based on nonlinear elastic models for incoherent and coherent interfaces are recovered as special cases for when the lattice distortion is constrained to coincide with the macroscopic deformation gradient, thereby excluding bulk dislocations. The formulation is purely spatial and needs no recourse to a fixed reference configuration or an elastic-plastic decomposition of the strain. Such a decomposition can be introduced however through an incremental elastic deformation superposed onto an already dislocated state, but leads to additional equilibrium conditions. The presentation emphasizes the role of configurational forces as they provide a natural framework for the description and interpretation of singularities and phase transitions.

Nematic elastomers exhibit large, spontaneous shape changes at the transition from the hightemperature isotropic phase to the low-temperature nematic phase. These finite deformations are studied here in the context of a nonlinear, properly invariant, variational theory that couples the orientational order and elastic deformation. The theory is based on the minimization of a freeenergy functional that consists of two contributions: a nematic one due to the interaction of the mesogenic units and an elastic one arising from the stretching of the cross-linked polymer chains. Suitable choices for these two contributions allow for large, reversible, spontaneous shape changes in which the elastic deformation can affect the isotropic-nematic transition temperature. The change in transition temperature as well as the magnitude of the resulting spontaneous deformation are illustrated for various parameter values. The theory includes soft elasticity as a special case but is not restricted to it.

Higher education in the global North, and exported elsewhere, is complicit in driving the planet’s socio-ecological crises by teaching how to most effectively marginalize and plunder Earth and human communities. As students and activists within the academic system, we take a firm stand to arrest this cycle, and to redirect education toward teaching how to create conditions for all life to thrive. In this paper, we articulate a research and education agenda for co-constructing knowledge and wisdom, and propose shifts in the ‘ologies from the current, destructive modes to intended regenerative counterparts. We offer to shift from an ontology of separation to that of interconnectedness; from an epistemology of domination to that of egalitarian relationship; and from an axiology of development to that of plural values for world- and meaning-making. Such paradigm shifts reflect the foundational aspirations of the consilient transdiscipline of ecological economics. We analyze several introductory university textbooks in economics, law, and natural sciences, to demonstrate how destructive ‘ologies are taught in North American universities, and how such teaching implicitly undermines critical inquiry and effective challenge. Our strategy for change is to provide a new theoretical framework for education: the regenerative ‘ologies of the Ecozoic’, based on biophysicality, embedded relationality, pluralism, and the sustainable well-being of all members in the community of life.