How Do I Calculate High Cycle Fatigue Life in Abaqus Using Strain Energy Models?

[BSids]

Hi all,

I'm hoping there's someone here who can give me a little help. So I've run a large number of fatigue tests, both stress and strain controlled, and using the data from these I've calibrated material constants for the chaboche model in Abaqus and run the simulations getting fairly similar results.

What I want to do now is determine the high cycle fatigue life (strain energy approach) of the material and compare it to available data. My main problem is choosing appropriate fatigue models and then calculating them. I was looking at the following models:

I know I need to look at the strain energy density output in Abaqus and need to post process the results some how (maybe a script in matlab). How do I take the abaqus output and get it in a form where I can determine fatigue life using the above equations?

Any help or guidance would be appreciated, I've been scouring the internet but can't find any info on it.

 

[Achy47]

Hi there,

Thank you for sharing your question with us. I would be happy to offer some guidance on your fatigue test data and determining high cycle fatigue life using different models.

Firstly, it's great that you have run a large number of fatigue tests and have calibrated material constants for the chaboche model in Abaqus. This is an important step in accurately simulating fatigue behavior.

In terms of determining high cycle fatigue life using the strain energy approach, there are a few different models that you can consider. The most commonly used models are the Coffin-Manson and Morrow models. Both of these models relate the number of cycles to failure to the maximum strain or stress amplitude. The Coffin-Manson model is typically used for ductile materials, while the Morrow model is more suitable for brittle materials.

To calculate the fatigue life using these models, you will need to use the strain energy density output from Abaqus. This output can be post-processed using a script in Matlab, as you mentioned. To do this, you will need to extract the strain energy density data from the Abaqus output file and then use it in the appropriate equation for the chosen fatigue model.

For example, if you are using the Coffin-Manson model, the equation would be Nf = C * (Δεmax)^-b, where Nf is the number of cycles to failure, C is a material constant, and b is the Coffin-Manson exponent. You can then use this equation to determine the fatigue life for your material.

I would also recommend checking the Abaqus documentation and forums for more information on post-processing fatigue data and using it in different fatigue models. Additionally, there are many research papers and articles available online that discuss the application of fatigue models in simulation software such as Abaqus.

I hope this helps and wish you all the best in your research. Please let me know if you have any further questions or need more clarification on anything I mentioned.