# Time History Fatigue Analysis - Ansys Static Structural Quer

• kepler456
In summary, the conversation is about testing a wind turbine hub for fatigue and determining the von mises stress input for non-constant amplitude loading. The problem is how to place different stresses at different parts of the hub, specifically at the three blade roots. The speaker needs to enter three time series plots and specify where each stress series acts, but is unsure how to do so based on their experience and online research. They mention a video that demonstrates how the software applies these stresses, but the location is not explicitly mentioned.
kepler456
I'm testing a part for fatigue, and I got a time series of Forces and Moments on three different parts of the body (A wind turbine hub). From the static structural fatigue analysis, I noticed that you need a von mises stress input - that's not a problem.

My problem is, how do I place different stresses at different parts of the hub? Basically I have time series data at three blade roots. All of the loads will have the same time step. I do not see a way to determine where you place the loads.

I don't understand . Please explain the problem more clearly .

If you go into Ansys > Static Structural. You have an option to work with Fatigue Stresses and determine Fatigue Life and Factor of Safety, etc. And one of the input methods allowed is a stress time series (For non constant amplitude loading).

I am working with a wind turbine hub, that has 3 blades. I have the stresses at the 3 blade roots that act on the hub. So, what I have is the stress time series at each of the hub/blade connections. I need to therefore enter 3 time series plots and tell the software where each of these stress series act. Right now from what I see and what I've seen online, people enter one time series plot and do not even mention the location of where it acts, they just mention additional static forces. The software some how applies these stresses on the system (probably at the location of the static force that the person has applied). If you check this video around the 8 minute mark you will see what I mean:

## Why is Time History Fatigue Analysis important in engineering and design?

Time History Fatigue Analysis is important because it allows engineers to accurately predict the fatigue life of a structure under dynamic loading, which is crucial for ensuring the safety and reliability of a design. It also helps in identifying potential failure points and making necessary design improvements to increase the longevity of a structure.

## What type of structures or components can be analyzed using Time History Fatigue Analysis?

Time History Fatigue Analysis can be applied to a wide range of structures and components, including but not limited to bridges, aircraft, wind turbines, and automotive parts. Any structure or component that is subjected to dynamic loading can benefit from this analysis method.

## What are the key steps involved in conducting a Time History Fatigue Analysis using Ansys Static Structural?

The key steps in conducting a Time History Fatigue Analysis using Ansys Static Structural include defining the loading conditions, creating a finite element model of the structure, specifying the material properties, defining the fatigue analysis settings, and interpreting the results to determine the fatigue life of the structure.

## Are there any limitations or assumptions to consider when using Time History Fatigue Analysis?

One limitation of Time History Fatigue Analysis is that it requires a significant amount of computational resources and time to perform the analysis. Assumptions are also made about the loading conditions and material properties, which may not always accurately reflect the real-world conditions. Additionally, the analysis may not account for potential changes in the structure over time, such as wear and tear, which can affect the fatigue life.

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