Figure 1.

The indentation of an inflated spherical shell considered here. (a) Idealized set-up and notation for the problem: a spherical shell of thickness h and undeformed radius R is subject to an internal pressure, p, while also being loaded by a vertical point force F at a pole. This causes a vertical deflection w(r) and, in particular, a displacement w(0) = −w₀ at the point of application of the force. (b) Three-dimensional cross section of a deformed shell with w₀ = 13 cm from numerical simulations with E = 70 GPa, v = 0.3, R = 1 m, h = 2 mm and p = 10⁴ Pa. (c) Image showing the experimental set-up in which a Pezzi ball (Ledragomma) is inflated and loaded by an indentor.