- #1

- 98

- 0

What assumption is made such that [itex] \sigma_{x,x} = \sigma_{x,-x} [/itex]? In other words, why is the normal stress on one face always equal and opposite to the normal stress on the opposite face?

It seems to me that [itex] \sigma_{x,x} [/itex] and [itex] \sigma_{x,-x} [/itex] do not need to be equal in order for the block of material to be in equilibrium, if the shear forces [itex] \tau_{x,j} [/itex] are allowed to balance it properly.