Question:
We say that a solid body is stress free when it is not subjected to any
applied loading or displacement restraint. Yet atmospheric pressure is
acting on it. Are the stresses in the solid zero ?
Answer:
Academically speaking no.
But practically, the stress due to atmospheric pressure is low compared with
the compressive stresses which ordinary materials can withstand.
Evidently so, or we would not be familiar with them in ordinaty conditions.
There are plenty of stresses in the element:
Residual stresses from manufacture
Chemical stresses from the atmosphere (and internally where the solid is
non-homogenous)
Thermal stresses
Radioactivity stresses
......to name but a few!
Fortunately most of these can be discounted depending upon the situation.
Even fluids are not immune when you think they have convection, flow etc to
act upon them.
So IMHO the stresses in a solid are not zero.
If that body is resting on something, then there are stresses in it
from its own mass and the reaction of the support.
If it is in orbit around earth, or some other body, and there are no
residual stresses from its manufacture, it must be nearly stress-free
- until space dust hits it.
Nope. The stresses should all be equal throughout the body, and they should
all be atmospheric pressure. Solids actually fail mostly through shearing
stresses, and not volumetric ones such as pressure.
