Understanding Interlaminar Stresses and Delamination — Lesson 1

This lesson covers the concept of interlaminar stresses in laminates, focusing on the mechanics of laminates and the classical lamination theory. It explains how to obtain the ABD Matrix from the classical lamination theory for a laminate and discusses the importance of symmetric laminate, anti-symmetric laminate, and quasi-isotropic laminate. The lesson also delves into the determination of stresses and strains in each ply of a laminate and the application of appropriate failure theories to determine the ply failure. It further explores the strength of laminate subjected to mechanical, thermal, or hydroscopic load. The lesson concludes by explaining the limitations of the classical lamination theory and the need to consider interlaminar stresses in the design of laminated structures.

Video Highlights

02:09 - Limitations of classical lamination theory
03:34 - Importance of considering interlaminar stresses in design
07:40 - Discussion on the in-plane and out-of-plane stresses in a laminate
15:13 - Discussion on the equilibrium equations
58:14 - Shear-extension coupling and its impact on the development of interlaminar stresses
01:03:18 - Influence of stacking sequence on interlaminar stresses and delamination

Key Takeaways

- Understanding the mechanics of laminates and the classical lamination theory is crucial in the design and analysis of laminated structures.
- The ABD Matrix derived from the classical lamination theory plays a significant role in determining the behavior of laminates under different loads.
- Different types of laminates, such as symmetric, anti-symmetric, and quasi-isotropic laminates, have unique properties and applications.
- Determining the stresses and strains in each ply of a laminate and applying appropriate failure theories helps in predicting the failure load of the laminate.
- The classical lamination theory, despite its usefulness, has limitations, especially when it comes to considering interlaminar stresses.