Calculate the shear modulus (G) of an isotropic material based on its Young's modulus and Poisson's ratio.
Last updated: March 2026 | By ForgeCalc Engineering
The shear modulus (G), also known as the modulus of rigidity, is a measure of a material's resistance to shear deformation. It is defined as the ratio of shear stress to shear strain.
For isotropic materials (materials that have the same properties in all directions), the shear modulus is mathematically related to the Young's modulus (E) and Poisson's ratio (ν). This relationship allows engineers to derive G when only E and ν are known.
Where:
• G is the shear modulus (GPa)
• E is the Young's modulus (GPa)
• ν (nu) is the Poisson's ratio
Young's modulus (E) measures resistance to axial deformation (stretching/compressing), while Shear modulus (G) measures resistance to twisting or sliding deformation.
For most engineering materials, Poisson's ratio is between 0 and 0.5. Looking at the formula, this means G will always be between 1/3 and 1/2 of E.
A perfectly rigid material would have an infinite shear modulus, meaning it would not deform at all under any amount of shear stress.
No. This formula is for isotropic materials. Composites (like carbon fiber) are anisotropic, meaning their properties change with direction, and G must be measured independently for each axis.
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