2.9. Hooke’s Law and Poisson’s Ratio

Most structural materials exhibit an initial region of the stress–strain diagram in which the material behaves both elastically and linearly. This linear elasticity is extremely important in engineering because many structures and machines are designed to experience relatively small deformations. For that straight-line portion of the diagram (Fig. 2.10a), stress is directly proportional to strain. If the normal stress acts in the x direction,

Equation 2.26