Lecture
This lecture covers the concepts of constraints and deformations in 3D, focusing on stress matrices, relative deformations, and normal stresses. It explains the relationship between stress and relative strain, the construction of stress matrices, and the importance of looking inside materials to understand internal forces. The instructor discusses the calculation of stresses from relative strains, the section method for finding internal forces, and the representation of stress components in 3D. Additionally, the lecture explores shear stresses, Hooke's law for shear stress, and the concept of reciprocal constraints. It concludes with an introduction to stress tensors and their application in analyzing stress states at different points in a material.