,so you mean to say is that the load still passes in the direction of maximum principal stress but the plastic failure for a ductile material starts to occur at 45 degrees to this direction i.e. 45 degrees to the load path. But my original question is why is the load supposed to pass through the direction of maximum principal stresses? In ANSYS Help, it is written that the locus of the directions of vector principal stresses suggests the paths of maximum load transfer throughout a body. My question is why?n