Gradient elasticity with surface energy: mode-III crack problem

In this paper an anisotropic strain-gradient dependent theory of elasticity is exploited, which contains both volumetric and surface energy gradient dependent terms. The theory is applied to the solution of the mode-III crack problem and is extending previous results by Aifantis and co-workers. The two boundary value problems corresponding to the “unclamped” and “clamped” crack tips, respectively, are solved analytically. It turns out that the first problem is physically questionable for some values of the surface energy parameter, whereas the second boundary value problem is leading to a cusping crack, which is consistent with Barenblatt's theory without the incorporation of artificial assumptions.