Lecture
This lecture covers the concept of relative deformations in 3D, including normal and shear strains, displacement fields, and the relation between displacement and deformation. It explains the definition and derivation of normal relative strain in 3D, the matrix of relative strains, and the engineering shear. The instructor demonstrates how to calculate relative strains and deformations in different directions, emphasizing the importance of understanding the changes in relative volume and shape of objects.