If you look at a typical Ashby diagram, you will notice that the fracture toughness based on K-factor is superimposed on all material classes.
Is this an ingenious solution or is it too simple?
The inclusion of fracture toughness based on the K-factor on an Ashby diagram can be considered an ingenious solution. The K-factor is a measure of the stress intensity factor at the tip of a crack and is a critical parameter in determining the fracture toughness of materials. By including this parameter on the Ashby diagram, it allows for a quick and easy comparison of the fracture toughness of different materials, regardless of their class or composition.
However, it should be noted that the K-factor only provides one aspect of the material's fracture behavior and other parameters such as crack growth resistance and microstructure should also be considered when selecting a material for a specific application. Additionally, the values on an Ashby diagram are typically plotted for a specific set of testing conditions and may not accurately represent the fracture toughness under different conditions. Therefore, while the inclusion of K-factor on an Ashby diagram is a useful tool, it should not be the only parameter considered when selecting a material for a specific application.
Febin Cherian John, thanks for your contribution.
We think that alternative parameters describe the situation better than K.
I find the question a bit of unclear and the edited chart with apples and oranges (implying Ashby has been mixing things and comparing apples with oranges) a bit aggressive.
The idea is simple, there are even standards how to measure fracture toughness in ductile materials. The chart includes mode 1 critical factor (there is an index 1 and c in K), therefore, it is an experimental value obtained by (for example) three-point bending specimen. Then dividing by Young's modulus, there is a measure for stiffness and toughness related questions in technical materials. There is nothing wrong or overly simplistic in this chart. It is a design guideline for an engineer to understand that technical ceramics are as good as metals, although very brittle. Without this quick estimation, one would avoid technical ceramics in impact including loading cases.
Ashby charts are a quick comparison for different technical cases. The ultimate values are necessary for fine-tuning. It is even stated in this way in the book at the very beginning.
- Badges
- Science topic
- Similar topics
- Physical Sciences
- Materials Science
- Plating