Sir, will there always be variation in stress sigmax to sigmax prime as we move from one plane to another?. And in the previous shown diagram of plane stress you took the same sigmax on both positive and -ve planes,why there was no any variation, i could not understand.
Is point O at the center of parallelopiped and not at the intersection of the three axes? Cause then only the perpendicular distance (to calculate moment around O) will be delx/2
I think that moment is taken from O point i.e. center of the thin sheet and since we calculate along only in one direction delta x will be the extension of the bar in both the direction. So in order to consider the extension in one direction delx/2 is taken. If it is wrong notify!?