# Shear Modulus

## Definition - What does Shear Modulus mean?

Shear modulus is the ratio of shear stress to shear strain. When shear modulus is calculated, it is always positive and expressed as an amount of force per unit area. Shear modulus is also known as modulus of rigidity. It is normally denoted by G, but is sometimes denoted by S.

**G = (Force Per unit Area) / (Transverse Displacement per unit initial length)**

The SI unit of Shear modulus is pascal (Pa), but it is expressed in GPa (Gigapascals) or in KSI (Thousands of pounds per square inch).

## Petropedia explains Shear Modulus

Shear modulus can be experimentally determined from the slope of a stress-strain curve created during tensile tests conducted on a sample of a material. The shear modulus of metals usually decreases when there is an increase in temperature. At high pressures, the shear modulus also appears to increase with the applied pressure. Correlations between the melting temperature, vacancy formation energy, and the shear modulus have been observed in many metals.

When the material has high tensile strength, its shearing power is also high, i.e., it has high shear modulus (not easily breakable) in ambient temperature conditions. Every material has a maximum shear withholding valve, above which when the force is applied on the material, it tends to strain or deform it along the plane of the direction of the force. Strain values tend to be rather small, however, in the calculations, strain is only a measure of deformation of a solid material before it breaks or fractures. Most solids like metals stretch only a small amount before breaking down.