Of stress and strain, which is the cause and which is the effect? Is stress a cause of strain, or is stress an effect of strain, or do they occur together (by applying Newton's third law)?
Asked
Active
Viewed 129 times
0
-
1Is this a chicken-and-egg thing? – joseph h Mar 31 '22 at 08:54
-
@josephh This is a conceptual question perfectly in line with this site policy. It should not be dismissed with a joke. – GiorgioP-DoomsdayClockIsAt-90 Mar 31 '22 at 09:20
-
@GiorgioP I wasn't being dismissive and I'm sorry you felt that way. – joseph h Mar 31 '22 at 09:24
1 Answers
3
There is no cause-effect relationship between them. However, this has nothing to do with Newton's third law because, although stress gives a force, once multiplied by a surface, strain measures deformations, not forces.
The absence of a cause-effect relation is probably more clearly understood by looking at the simplest case of isotropic stress (pressure). In that case, the strain is simply described by the volume. We can use the volume to control the pressure or the opposite, depending on the experimental conditions. However, it is not a cause-effect relation because one deals with physical quantities at the same time. It would be possible to speak about cause-effect only in the case of changes. We could say that a change in volume is the cause of a change of pressure or the opposite, depending on the experimental conditions.
