Tensile deformation can be defined as the tendency of a material to change shape or deform when a tensile force is applied. Deformation takes place when due to tensile strain on elastic material, internal intermolecular forces oppose the applied force. If the intermolecular forces can overcome the applied force, the material can return to its original state.
However; if the applied force is greater, permanent deformation or structural failure can take place.
When a tensile force is applied to a material, it develops a stress corresponding to the applied force (P), contracting the cross-section and elongating the length (ΔL). The tensile strain ε is expressed as ε = ΔL/L.
If the compressive force is applied, the compressive strain is expressed as ε = -ΔL/L. Based on Hooke's law, the relation between stress and strain is expressed as σ = Eε, where σ – stress, E – Young's modulus and ε – strain.
On receiving the tensile force, the material expands in the axial direction (longitudinal strain) while contracting in the transverse direction (transverse strain). The ratio between the longitudinal and transverse strains is known as Poisson's ratio.