Introduction to Plasticity

This lecture introduces the concept of plasticity in structures, focusing on the formulation of elastoplasticity. Topics covered include the definition of displacement before and after sliding, force vectors, yield criteria, and the computation of plastic increments. The lecture also discusses the relationship between forces and displacements, the yield function, and the loading-unloading conditions. Emphasis is placed on the constitutive level, incremental methods (explicit and implicit), and the iterative approach for computing stresses. The importance of defining the yield surface and plastic flow is highlighted, along with the implications of non-associated flow in elastoplastic stiffness.