Lecture
This lecture covers the basic concept of the yield surface and its relation to plastic deformation in metallic materials. It explains the phenomenon of necking in ductile materials and the mechanical instability associated with it. The instructor discusses the stress-strain curves, plastic deformation behavior, and the criteria for the initiation of necking. Additionally, the lecture explores the implications of strain localization and deformation homogeneity in materials subjected to mechanical tests, emphasizing the importance of understanding material behavior under different loading conditions.