1. Circular cylinder pressure vessels under external hydrostatic pressure are in a state of generalized plane strain (i.e., axial strain is constant). A consequence of this state is that circumferential, axial and radial stresses are compressive; corresponding circumferential and axial strain are also compressive. But, radial strain is tensile. https://www.researchgate.net/publication/373332365.

2. Such Alumina ceramic pressure vessels exhibit cracks that emanate from the bearing end then grow and arrest parallel to this tensile stress field. https://www.researchgate.net/publication/355935439, https://www.researchgate.net/publication/376582543