Abstract
To draw conclusions as regards the stability and modelling limits of the investigated continuum, we consider a family of infinitesimal isotropic generalized continuum models (Mindlin–Eringen micromorphic, relaxed micromorphic continuum, Cosserat, micropolar, microstretch, microstrain, microvoid, indeterminate couple stress, second gradient elasticity, etc.) and solve analytically the simple shear problem of an infinite stripe. A qualitative measure characterizing the different generalized continuum moduli is given by the shear stiffness \(\mu ^{*}\). This stiffness is in general length-scale dependent. Interesting limit cases are highlighted, which allow to interpret some of the appearing material parameter of the investigated continua.
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Notes
The following energy expression has been used in [41]: \(W \left( \varvec{\nabla u}, \varvec{P}, \varvec{\nabla P}\right) = \mu \left\Vert \hbox {sym} \, \varvec{\nabla u} \right\Vert ^2 + \lambda /2 \, \hbox {tr}^2 \left( \varvec{\nabla u} \right) + \alpha \, \mu \left\Vert \varvec{\nabla u} - \varvec{P} \right\Vert ^2 + \alpha \, \lambda /2 \, \hbox {tr}^2 \left( \varvec{\nabla u} - \varvec{P} \right) +\mu \, L_{c}^2/2 \, \left\Vert \varvec{\nabla P} \right\Vert ^2 \). This formulations is not reconcilable with the relaxed micromorphic model even if we neglect the curvature part.
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Acknowledgements
AM acknowledge funding from the French Research Agency ANR, “METASMART” (ANR-17CE08-0006). AM and GR acknowledges support from IDEXLYON in the framework of the “Programme Investissement d’Avenir” ANR-16-IDEX-0005.
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Rizzi, G., Hütter, G., Madeo, A. et al. Analytical solutions of the simple shear problem for micromorphic models and other generalized continua. Arch Appl Mech 91, 2237–2254 (2021). https://doi.org/10.1007/s00419-021-01881-w
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DOI: https://doi.org/10.1007/s00419-021-01881-w