Hygrothermal Behavior of Lamina — Lesson 3

This lesson covers the concept of hygrothermal stresses in lamina, specifically in fiber-reinforced polymer composites. It delves into the effects of temperature and moisture changes on the mechanical behavior of these composites. The lesson explains how these environmental changes can affect the properties of the matrix and induce residual stress. It also discusses the transformation of compliance and stiffness matrix from the local axis to the global axis. The lesson further elaborates on the macromechanics of lamina, including the stress-strain relationship, failure criteria, and the impact of environmental conditions on the behavior of polymer composites. For instance, it explains how a change in temperature during fabrication can lead to a change in the composite's dimensions, and how moisture absorption can affect its stiffness.

Video Highlights

02:12 - Discussion on the effects of temperature and moisture changes on polymer composites
04:15 - Explanation of the impact of these changes on the properties of the matrix
08:37 - Discussion on the concept of residual stress
13:14 - Explanation of the effects of temperature and moisture changes on a fiber-reinforced polymer matrix composite
23:14 - Hygrothermal stresses on a general orthotropic lamina
33:44 - Hygrothermal stresses on an unidirectional glass epoxy lamina
38:30 - Hygrothermal stresses on a fully restrained lamina
39:47 - Hygrothermal stresses on a fully unrestrained lamina
43:20 - Hygrothermal stresses on a 45 degree lamina

Key Takeaways

- Environmental changes, specifically temperature and moisture changes, significantly affect the mechanical behavior of fiber-reinforced polymer composites.
- These changes can affect the properties of the matrix, inducing residual stress and altering matrix-dominated properties such as transverse strength and stiffness.
- The transformation of compliance and stiffness matrix from the local axis to the global axis is crucial in understanding the behavior of these composites under different environmental conditions.
- The macromechanics of lamina involves understanding the stress-strain relationship, failure criteria, and the impact of environmental conditions on the behavior of polymer composites.