Show tot Hill's yield criterion XXXXXXXXXXreduces to a plane stress form: when plane stresses q,, c^ and TV are applied within the plane of a thin sheet and aligned with the orthotropic axes x and y...

Show tot Hill's yield criterion (3.27) reduces to a plane stress form:

when plane stresses q,, c^ and TV are applied within the plane of a thin sheet and aligned with the orthotropic axes x and y (z is through the thickness). Use this equation to show tot the variation in yield stress F with orientation #to x within the plane of the sheet, is given by: