Dear fellow contact mechanicists,
it is well known that the elastic edge singularity for the contact pressure in the vicinity of a singular contact boundary with a smooth boundary line is analogous to the elastic stress singularity for a crack with a smooth crack frontline, and of the form p(s) ~ s^(-1/2).
Now, what happens at a singular sharp corner of the contact boundary, e.g., under the indentation by a rigid square flat punch? I would assume, the exponent of the pressure singularity depends on the inner angle \theta of the corner, and will be p ~ 1/s (?) for \theta = 0, p ~ s^(-1/2) for \theta = \pi (the known edge singularity), and there is no singularity for \theta = 2\pi.
Are there asymptotic analytic solutions for this kind of singular indentation problems?
For the "crack analogue", the corresponding task has been solved in the work
Xu, L.; Kundu, T.: Stress Singularities at Crack Comers. Journal of Elasticity, 39, 1–16 (1995).
However, I think, the "analogue" only works for the edge singularity; for example, for a right-angled crack corner the singularity should be \sigma(s) ~ s^(-0.9) (approximately), but in a boundary element simulation for the indentation by a square flat punch, I obtain the asymptotic behavior p ~ s^(-0.7) (approximately).
Best regards,
Emanuel