What is the use of Strain energy density in FEA for static stress analysis?

[pike12]

I am trying to conduct fatigue life analysis for high cycle fatigue with stresses under yield. For that, I am trying to get stresses through NASTRAN. The model runs okay but there is a warning displayed saying 'high values of strain energy. the normal values should be zero.'

Is strain energy more of a quality check like internal energy monitoring for simulations?

 

[MotorCity]

You would be better off moving this to the Structural forum. This question is not BIM related so you may not get any responses here.
But while I'm here (and not at all familiar with NASTRAN), high strain values may indicate large deformations. Since they are below yield, they should be elastic (not plastic) deformations. Perhaps your deformations are exceeding some allowable deformation that you or the software specified?

 

[pike12]

Hi @MotorCity.
I realized it much later that I was posting the question in the wrong forum. Thank you for answering it though. Your answer is right. It serves as a flag to check on unusal deformations happening in the model.
Appreciate your help

 

[steinryan28]

Strain energy is not typically a quality check like internal energy monitoring in finite element analysis (FEA) simulations, but it can provide valuable information about the behavior of your structure or component. The warning you received regarding "high values of strain energy" suggests that there may be an issue with your analysis or model setup that should be investigated.

Strain energy is a measure of the internal energy stored within a material due to deformation. In the context of FEA, it can help you understand how much energy is being absorbed by the structure during loading and how much is being released when the load is removed. Here are some points to consider regarding the warning you received:

[ul]
[li]Material Properties: Ensure that you have defined the material properties (such as Young's modulus and Poisson's ratio) correctly for your analysis. Incorrect material properties can lead to unrealistic strain energy values.[/li]

[li]Boundary Conditions: Check your boundary conditions. Incorrectly constrained or overly restrictive boundary conditions can result in unrealistic strain energy values. Ensure that your model is properly constrained to represent the physical behavior of the structure.[/li]

[li]Load Application: Verify that the loads you are applying to the model are realistic and appropriate for the analysis you are conducting. Incorrectly applied loads can lead to unrealistic results.[/li]

[li]Mesh Quality: Ensure that your mesh is of good quality, with appropriately sized elements. Poorly meshed models can produce inaccurate results, including strain energy values.[/li]

[li]Convergence: Check if your analysis has converged properly. Convergence issues can lead to unrealistic strain energy values. You may need to refine the mesh, adjust solver settings, or use a more appropriate element type.[/li]

[li]Material Nonlinearity: If your analysis involves material nonlinearity (e.g., plasticity), make sure your material model is correctly defined and the yield criteria are appropriate.[/li]

[li]Dynamic Effects: If your analysis is dynamic, consider any dynamic effects that may be contributing to the strain energy values.[/li]
[/ul]

While strain energy itself is not a quality check in the same way as some other simulation parameters, it can provide insights into the behavior of your structure. High values of strain energy may indicate that your structure is absorbing a significant amount of energy during loading, which could be due to nonlinear material behavior, overloading, or other issues.

To diagnose the specific problem in your analysis, it's important to review your model setup, boundary conditions, material properties, and loading conditions in detail, and consider consulting with experienced engineers or analysts if needed.