Physical meaning of elastic constants in Cosserat, void, and microstretch elasticity

The physical meaning of Cosserat, void, and microstretch elastic constants is analyzed and interpreted.Various torsion experiment designs provide a clear path to extract Cosserat elastic constants independently of any dilatation gradient sensitivity the material may have.For void elasticity (with sensitivity to dilatation gradients) there is no known quasistatic modality to demonstrate phenomena or extract elastic constants independently of any sensitivity to rotation gradients.Wave methods may be appropriate if there is minimal viscoelastic dispersion.Microstretch elasticity, which includes sensitivity to gradients of rotation and of dilatation could account for bending effects larger than those of Cosserat elasticity.