Indentation Test: How can you tell if the material yielded?

[NazD]

Homework Statement

I am modeling a 2D indentation test of pure Aluminum in ANSYS using non-linear analysis. The objective is to determine the minimum force required at the rigid indenter in order to achieve yielding of the Aluminum block. The indenter is 2 micrometers in width and is rigid.

Homework Equations

My main question is how can I tell if the material has yielded in ANSYS? I assumed it would yield once it reaches its yield strength of approximately 90 MPa but according to the Slip Line Theory, the material will yield at almost 250 MPa. How do I know the stress at which the material will yield?

The Attempt at a Solution

I ran the simulations by specifying a value for a remote displacement and then checked the stress levels. Does anyone have an idea how I can do this another way and find out the point at which the aluminum yields?

Thank you for your help!

 

[KataKoniK]

it is important to understand the behavior of materials under different conditions, such as in this indentation test. In order to determine the yield point of the aluminum, there are a few factors that need to be taken into consideration.

Firstly, it is important to understand that the yield strength of a material is not a fixed value, but rather a range. This range can vary depending on factors such as temperature, strain rate, and microstructure of the material. Therefore, the yield strength of aluminum can vary from 90 MPa to 250 MPa.

In ANSYS, you can determine the yield point of the aluminum by looking at the stress-strain curve. This curve will show the relationship between stress and strain, and the yield point can be identified as the point where the curve starts to deviate from linearity. This is known as the yield point or yield strength.

Another way to determine the yield point is by looking at the von Mises stress. This is a measure of the equivalent stress in the material and is commonly used in plasticity analysis. In ANSYS, you can plot the von Mises stress distribution and identify the point at which it exceeds the yield strength of the material.

It is also important to keep in mind that the yield point can also be affected by the size and geometry of the indentation. In order to accurately determine the yield point, it is recommended to run multiple simulations with different indentation sizes and compare the results.

I hope this helps in your analysis. Best of luck with your project!