Principle Stress, Hydrostatic and Deviatoric Components of Stress — Lesson 1

This lesson covers the development of a finite element model for elasto-plastic analysis in welding processes. It explains how to predict residual stress associated with welding processes by combining temperature and residual stress distribution. The lesson also delves into understanding plasticity models, yield criteria, hardening rules, and flow rules applicable in finite element-based stress analysis models. It further discusses the formulation of stress analysis models, prediction of residual stress, solution strategies, and the incorporation of phase transformation effects. The lesson uses the example of a three-dimensional body to illustrate the concepts.

Video Highlights

01:29 - Concept of stress analysis and how it is used in the welding process
04:31 - Concept of principal stress and how it can be derived from the three-dimensional state of stress
18:00 - How the state of stress can be divided into hydrostatic stress and deviatoric stress components
33:56 - Concept of strain hardening and how it affects the behavior of materials
42:00 - How the yield surface can be represented mathematically

Key Takeaways

- Bauschinger effect refers to the phenomenon where the yield stress in tension is not the same as the yield stress in compression.
- Strain hardening is the concept where the strength of a material increases as it is deformed beyond its yield point.
- An effective stress, which characterizes the state of applied stress, is compared with a known material property to determine if failure or yielding will occur.