ABSTRACT
Sign Convention 1. Compressive stresses are positive and tensile stresses are negative. 2. Shear stresses are considered as positive if they give a clockwise moment about a point
above the stressed plane as shown in Fig. 8.8(b), otherwise negative. The normal stresses are taken as abscissa and the shear stresses as ordinates. It is
assumed the normal stresses ax ' a y and the shear stress 'l'xy ('l'xy = 'l'yx) acting on the surface of the element are known. Two points PI and P2 may now be plotted in Fig. 8.8(b), whose coordinates are
If the points PI and P2 are joined, the line intersects the abscissa at point C whose coordinates are [( ax + a y)/2, 0].
