Rigidity and functional properties of $\mathrm{BD}_{dev}(Ω)$
Marco Caroccia, Nicolas Van Goethem
TL;DR
The paper studies the space $\mathrm{BD}_{\mathrm{dev}}$ of functions with bounded deviatoric deformation, identifying a sharp rigidity structure for maps whose deviatoric part lies in the wave cone and constructing an explicit kernel projection to enable iterative blow-up arguments for relaxation and homogenization.A fourth-order annihilator is computed to characterize the wave cone, allowing a precise description of the singular parts of $\mathcal{E}_d u$ and the decomposition into absolutely continuous, jump, and Cantor pieces with explicit polar data.The main contributions are (i) a rigidity theorem for $\mathrm{BD}_{\mathrm{dev}}$ maps with constant polar in the wave cone, (ii) an explicit projection $\mathcal{R}_K$ onto $\mathrm{Ker}({\mathcal{E}}_d)$, and (iii) a framework enabling integral representation and homogenization for energies that depend on $u$ as well as $\mathcal{E}_d u$, with applications to material science.These results extend the BD theory to deviatoric settings, overcoming invariance issues and enabling an iterative blow-up approach for relaxation problems and materials modeling where shear-dominated effects are central.
Abstract
We provide a structural analysis of the space of functions of bounded deviatoric deformation, $\mathrm{BD}_{dev}$, which arises in models of plasticity and fluid mechanics. The main result is the identification of the annihilator and a rigidity theorem for $\mathrm{BD}_{dev}$-maps with constant polar vector in the wave cone characterizing the structure of singularities for such maps. This result, together with an explicit kernel projection operator, enables an iterative blow-up procedure for relaxation and homogenization problems, allowing for integrands with explicit dependence on $u$ as well as $\mathcal{E}_d u$. Our approach overcomes several difficulties as compared to the $\mathrm{BD}$ case, in particular due to the lack of invariance of $\mathcal{E}_d$ under orthogonalization of the polar directions. Applications to integral representation and Material science are discussed.
