Lecture
This lecture discusses the concept of eigenstrains, which are deformations in a body not caused by stress. It explains how these strains can be created in a material and the importance of considering them in mechanics. The instructor presents examples of materials where eigenstrains play a significant role, such as piezoelectric materials. The lecture also covers the transformation strains that occur in bodies when they change shape due to factors unrelated to applied stress. Various scenarios are analyzed to illustrate the development of stresses in constrained bodies during transformation. The discussion includes the composition of total strain, the role of Hooke's law, and the implications of different behaviors in materials.