Material Constant
Resistance to deformation by opposing forces acting parallel to the surface of a material is defined by a numerical value. The shear modulus relates the shear stress to the resulting shear strain within the elastic limit. It is also known as the modulus of rigidity and is a fundamental property for structural analysis.
Physical Relationship
Relationships between different elastic constants allow for the calculation of this value from other properties. For isotropic materials, the shear modulus depends on the elastic modulus and the Poisson ratio of the substance.
Experimental Determination
Torsion testing or ultrasonic wave propagation provides the data for measurement. Finding the shear modulus involves applying a known torque to a cylindrical specimen and measuring the angle of twist.
Structural Design
Engineering calculations for springs and structural beams depend on accurate modulus values. The shear modulus identifies the stiffness of a component when subjected to transverse loads. Verification of the material property ensures that the final product will meet the deflection and vibration requirements.
Materials like rubber have a very low shear modulus compared to structural steel or titanium. This property is verified using dynamic mechanical analysis where the sample is subjected to oscillatory shear at various frequencies. The resulting storage and loss moduli provide a complete picture of the material’s viscoelastic behavior under load.
