Sign Conventions for Shear Stresses and Strains

1.) Shear stress acting on a positive face of an element is positive if it acts in the positive direction of one of the coordinate axes and negative if it acts in the negative direction of an axis. Shear stress acting on a negative face of an element is positive if it acts in the negative direction of an axis and negative if it acts in a positive direction.

2.) Shear strain in an element is positive when the angle between two positive faces (or two negative faces) is reduced. The strain is negative when the angle between two positive (or two negative) faces is increased.

3. )Hooke’s Law in Shear

4.) The moduli of elasticity in tension and shear are related by the following equation: