Material Nonlinearity II — Lesson 4

This lesson covers the concept of elastoplastic behavior in finite element analysis, focusing on the application of this concept in thermomechanical models associated with welding fusion processes. The lesson explains the irreversible non-linearity in the light of the plasticity model and how Newton Raphson method or direct iterative techniques work in finite element-based models. It also discusses the importance of strain rate, loading history, temperature, and loading direction in influencing the non-linearity in metals and non-metals. The lesson further explains how to perform incremental elastoplastic stress analysis and the construction of elastoplastic matrix for thermomechanical analysis.

Video Highlights

01:40 - Discussion on the unique tensile testing diagram and the relationship between stress and strain
04:01 - Overview of the finite element analysis process, including domain discretization, thermal analysis, and stress analysis
06:08 - Concept of plastic work and its role in determining the plastic multiplier in elastoplastic behavior
22:22 - Construction of the elastoplastic matrix in finite element analysis and the role of deviatoric stress components
37:15 - Procedure for elastoplastic stress analysis

Key Takeaways

- Elastoplastic behavior of materials is a crucial example of irreversible non-linearity.
- The Newton Raphson method or direct iterative techniques are commonly used in finite element-based models.
- Strain rate, loading history, temperature, and loading direction greatly influence the non-linearity in metals and non-metals.
- Incremental elastoplastic stress analysis is performed to understand the behavior of materials under different loads.
- The construction of an elastoplastic matrix is essential for thermomechanical analysis.