Discussion Overview
The discussion revolves around the relationship between initial yield stress and tensile strength, particularly in the context of non-linear finite element analysis (FEA) for plastics. Participants explore how to calculate or estimate initial yield stress from available material properties and stress-strain curves.
Discussion Character
- Debate/contested
- Technical explanation
- Mathematical reasoning
Main Points Raised
- Some participants question whether initial yield stress and yield strength are the same, with one participant seeking clarification on the definitions and their applicability in FEA.
- There is a suggestion that the commonly specified property is tensile strength due to the nature of materials, particularly plastics, which may harden with deformation.
- One participant notes that they achieve good results in FEA when using yield strength as initial yield strength, indicating a possible overlap between the two terms.
- Another participant emphasizes the importance of understanding the stress-strain curve for ductile materials before proceeding with FEA, suggesting a need for foundational knowledge.
- A later reply provides resources for obtaining full stress-strain curves for specific resin types, highlighting the difficulty in defining yield points for plastics compared to metals.
- It is mentioned that yield strength is typically defined at a strain offset of 0.002, and that yield stress can be derived from stress-strain curves.
Areas of Agreement / Disagreement
Participants express differing views on whether initial yield stress and yield strength are equivalent, and there is no consensus on a formula for calculating yield stress. The discussion remains unresolved regarding the definitions and their implications for FEA.
Contextual Notes
Participants note the challenges in defining the elastic and plastic regions for plastics, as well as the limitations of relying solely on tensile strength data without access to comprehensive stress-strain curves.