Hooke’s law describes the relationship between [[Stress|stress]] and [[Strain|strain]] in the [[Elastic|elastic]] region of the stress strain curve. The relationship between stress and strain is linear in the elastic region, as such the general form of Hooke’s law states: $\varepsilon_{ij}=\dfrac{\sigma_{ij}-\nu(\sigma_{kk}\delta_{ij}-\sigma_{ij})}{E}$ Where for this equation $\delta_{ij}$ is the [[Kronecker Delta|Kronecker delta]] and $E$ is Young's modulus, which is dependent on the material, and finally $\nu$ is [[Poisson's Ratio|Poisson's ratio]] which also depends on the material. For [[Normal Stress|normal stress]] Hooke's law simplifies to: $\varepsilon = \dfrac{\sigma}{E}$ Using Hooke's law for axial [[Force|loading]] we can find the deformation directly: $\delta=\dfrac{FL}{AE}$