Hygrothermal Behaviour of Laminates — Lesson 3

This lesson covers the concept of hygrothermal stresses in laminates, focusing on the derivation of effective engineering constants for a laminate. It explains how these constants are derived from the elements of the ABBD matrix and how they can only be obtained for symmetric laminates. The lesson also discusses the effects of temperature change and moisture absorption on laminates, leading to the development of residual thermal and hygroscopic stresses. The lesson further explains how to calculate these stresses using the reduced transform stiffness matrix and the stress transformation matrix. An example of an n-layer laminate is used to illustrate the process of determining hygrothermal residual stresses.

Video Highlights

02:15 - Effects of temperature change and moisture absorption on laminates
09:00 - Calculation of residual thermal and hygroscopic stresses
13:14 - Determining hygrothermal residual stresses using an n-layer laminate
31:10 - Equivalent thermal load
39:00 - Equivalent Moment Resultant
01:03:16 - Free Thermal Strain
01:04:49 - Residual Thermal Strain

Key Takeaways

- Effective engineering constants for a laminate are derived from the elements of the ABBD matrix.
- These constants can only be obtained for symmetric laminates.
- Temperature change and moisture absorption can cause residual thermal and hygroscopic stresses in laminates.
- These stresses can be calculated using the reduced transform stiffness matrix and the stress transformation matrix.
- The process of determining hygrothermal residual stresses involves considering an n-layer laminate and using the known values of each lamina.