The inverse energy cascade of two-dimensional (2D) turbulence is often represented phenomenologically by a Newtonian stress-strain relation with a ‘negative eddy-viscosity’. Here we develop a fundamental approach to a turbulent constitutive law for the 2D inverse cascade, based upon a convergent multi-scale gradient (MSG) expansion. To first order in gradients we find that the turbulent stress ...

The aim of this paper is to study the elastic stress and strain fields of dislocations and disclinations in the framework of Mindlin’s gradient elasticity. We consider simple but rigorous versions of Mindlin’s first gradient elasticity with one material length (gradient coefficient). Using the stress function method, we find modified stress functions for all six types of Volterra defects (dislo...

This paper first considers the approximation of peridynamics by strain-gradient models in the linear, one-dimensional setting. Strain-gradient expansions that approximate the peridynamic dispersion relation using Taylor series are compared to strain-gradient models that approximate the peridynamic elastic energy. The dynamic and energetic expansions differ from each other, and neither captures ...

To explain the size effect found in the testing of plastic behavior of metals on the micrometer scale, four theories of strain-gradient plasticity, representing generalizations of the deformation theory of plasticity, have been developed since 1993––the pioneering original theory of Fleck and Hutchinson in two subsequent versions, the mechanism-based strain-gradient (MSG) plasticity of Gao and ...

We present an atomic scale theory of lattice distortions using strain-related variables and their constraint equations. Our approach connects constrained atomic length scale variations to continuum elasticity and describes elasticity at several length scales. We apply the approach to a two-dimensional square lattice with a monatomic basis and find the elastic deformations and hierarchical atomi...

In this article, the free vibration analysis of magneto-electro-elastic (MEE) Timoshenko micro beam model based on surface stress effect and modified strain gradient theory (MSGT) under moving nano-particle is presented. The governing equations of motion using Hamilton’s principle are derived and these equations are solved using differential quadrature method (DQM). The effects of dimensionless...

A continuum thermodynamics formulation for micromagnetics coupled with mechanics is devised to model the evolution of magnetic domain and martensite twin structures in ferromagnetic shape memory alloys. The theory falls into the class of phase-field or diffuseinterface modeling approaches. In addition to the standard mechanical and magnetic balance laws, two sets of micro-forces and their assoc...