Strength of materials comprises the study of deformable bodies subject to applied forces and moments. Stress and strain are quantities used to characterize the strength and deformation of a component. When the properties of an engineering material are tested and recorded in a handbook, the definition of stress and strain allow the test data to be applied to virtually any structure. As the force is initially applied, the stress increases proportionally with strain. If the material is a linear elastic material, stress and strain in the elastic range will be related by Hooke’s Law. Applied torque creates a shear stress that causes the shaft to twist. In the elastic range of the material, the shear stress is related to the shear strain.
By Gary Conner
By George N Bullen FSME