Application of Griffith Theory, Irwin-Orowan Modification of Griffith Theory, Assessment of Effect of Dynamic Loading — Lesson 4

This lesson covers the Griffith theory of brittle fracture, which explains the energy conversion from strain energy to surface energy during the crack operation. It further delves into the concept of energy conversion being irreversible in thermodynamics. The lesson also discusses the critical load capacity of a component and how it can be calculated using the given formula. It provides examples to illustrate the application of Griffith’s theory in selecting materials for rocket motor cases. The lesson also introduces the Irwin Orowan Modification of Griffith theory, which caters to some amount of plastic deformation during crack propagation. It concludes with the application of the stress intensity factor approach in design and safety assessment.

Video Highlights

00:36 - Introduction to Griffith theory of brittle fracture and energy conversion from strain energy form to surface energy form
15:11 - Explanation of the Irwin Orowan Modification of Griffith theory.
29:11 - Explanation of the stress intensity factor approach by Irwin
39:58 - Application of the stress intensity factor approach in design and safety assessment.
46:57 - Explanation of the impact of dynamic loading on a component.

Key Takeaways

- The Griffith theory of brittle fracture explains the energy conversion from strain energy to surface energy during the crack operation.
- The energy conversion is irreversible in thermodynamics.
- The critical load capacity of a component can be calculated using the given formula.
- The Irwin Orowan Modification of Griffith theory caters to some amount of plastic deformation during crack propagation.
- The stress intensity factor approach can be applied in design and safety assessment.