12.1 An element in plane stress on the fuselage of an airplane (figure part a) is subjected to compressive stresses of magnitude 42 MPa in the horizontal direction and tensile stresses of magnitude 9.5 MPa in the vertical direction (see figure part b). Also, shear stresses of magnitude 15.5 MPa act in the directions shown. Determine the stresses acting on an element oriented at a clockwise angle of 40 from the horizontal. Show these stresses on a sketch of an element oriented at this angle. 9.5 MPa (a) T (b) 42 MPa 15.5 MPa