| a coefficient of elasticity of a substance, expressing the ratio between the force per unit area (shearing stress) that laterally deforms the substance and the shear (shearing strain) that is produced by this force. |
| shear modulus
See under modulus of elasticity. |
shear modulus
numerical constant that describes the elastic properties of a solid under the application of transverse internal forces such as arise, for example, in torsion, as in twisting a metal pipe about its lengthwise axis. Within such a material any small cubic volume is slightly distorted in such a way that two of its faces slide parallel to each other a small distance and two other faces change from squares to diamond shapes. The shear modulus is a measure of the ability of a material to resist transverse deformations and is a valid index of elastic behaviour only for small deformations, after which the material is able to return to its original configuration. Large shearing forces lead to flow and permanent deformation or fracture. The shear modulus is also known as the rigidity
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