fatigue damage model

[xibaiw]

Hello Mr.Willberg and Mr.Hesse,
Is there a way to implement a fatigue damage model in the current version of PeriLab? Or does PeriLab have plans to incorporate a fatigue damage model in future updates?

[xibaiw]

by the way, how can i use reference temperature in input file ?

[JTHesse]

Take a look at this example.

[JTHesse]

Hi @xibaiw, it really depends on what kind of fatigue damage model you want to simulate. Fatigue can be quite simple and already achieved with the current damage models. Can you further explain what you want to achieve?

[xibaiw]

I currently want to simulate the damage progression in a plate under cyclic mechanical loading. If possible, I would also like to further simulate the damage caused by cyclic temperature-varying loading on the plate.

[CWillberg]

@xibaiw "I currently want to simulate the damage progression in a plate under cyclic mechanical loading." This is currently possible. However, it takes time to simulate. With temperature variation as well. However, if you analyse temperature be aware that for most of the materials it leads to reduced fatigue resistence. For metals you uses a strain based approach if your thermal strains exceed the yield strain.

[xibaiw]

How is this implemented in PeriLab? Is the stiffness reduced based on the number of cycles?

[JTHesse]

Cyclic mechanical loading can be used with the correct boundary condition: f.e.: 50 * sin(2 * pi * 10 * t - pi / 2) + 50
In PeriHub an amplitude generator is implemented for those BCs.

[CWillberg]

"Is the stiffness reduced based on the number of cycles?"
No. You can do that, if you want. Alternatively you can develope a function to reduce the bond strength in dependency of the cycles. We can support you, if you specify in detail what you want to do.

[xibaiw]

"Is the stiffness reduced based on the number of cycles?" No. You can do that, if you want. Alternatively you can develope a function to reduce the bond strength in dependency of the cycles. We can support you, if you specify in detail what you want to do.

maybe, i can try to do sth about the function.

[xibaiw]

and another question is, in contact model, is the parameter Contact Stiffness equals the Spring Constant in Peridigm? if not, how can i calculate the Contact Stiffness?

[xibaiw]

there's sth wrong with the contact model i think, the example of contact doesn't work well. @CWillberg @JTHesse

[JTHesse]

Good to know, fix is on the way ;)

[JTHesse]

It's already working, just update your repo ;)

[CWillberg]

Hello,

yes it is. Be careful with the model, we currently testing it. You chose the stiffness yourself, because it is an Penalty stiffness. If it is higher the contact is better approximated, but you will get numerical issues.