**3. Crystal Plasticity**

Crystal plasticity (CP) is known as a fundamentally multi-dimensional approach beginning at the atomic level (dislocation cores) across sub-structural dislocation engagements in a single grain and up to the macroscopic mechanical behavior of the material. The multi-scale specialty and extensive research status of CP allow scientists and engineers to concentrate on different methodological domains. Plastic slip can be regarded as the utmost common plastic deformation mechanism in crystalline solids and metals. Typically, the slip system is found across the pre-established directions and planes in the form of plastic shearing, which is taken care of by the atomic arrangement at a regular crystal structure. The constitutive equations, theories, and mechanisms are derived keeping in mind the deformation characteristics of the materials on meso and micron levels. It derives the significant alteration of crystal plasticity from classical plasticity models for computational analysis. The hypothesis is derived much ahead in context to the continuum mechanics, stress fields, and other essential variables. For single and poly-crystals, the inelastic deformation models are successfully obtained and promoted the researchers to apply the crystal plasticity models for predicting the fatigue fracture and damage analysis. Besides, the freedom to apply various empirical formulas at the scale level permits solicitation of continuum dislocation simulations for determining crack initiation and propagation behavior [27].
