Learning Forum

[javat33489]

Hi all.
I made a calculation for drilling rock. In my calculations, the drill drilled through the SPG die by 10 mm. The purpose of the calculation is to check the drill teeth.
I also performed a tooth fatigue analysis, but the number of cycles is not displayed.

I have two questions.
1. How to calculate fatigue in LS-Prepost so as to understand how the teeth will get tired after 1000 meters or 2000 meters?
2. How to calculate tooth fatigue in Ansys ncode Workbench to understand how the teeth will get tired after 1000 meters or 2000 meters? Using the D3plot file from Ls-Dyna.
What tools should you use?
I would be very grateful for the information.

[javat33489]

Help please.

[Ashish Khemka]

Hello,

Please see if the following links help: 

advances-in-fatigue-analysis-with-ls-dyna (dynalook.com)

Application of LS-DYNA  in Structural Fatigue Analysis and Post-Processing with LS-PrePost  — Dynalook

Understanding Mechanical Fatigue in Engineering Designs (simutechgroup.com)

Regards,

Ashish Khemka

 

[javat33489]

Thanks for your reply sir. But there is no answer in these links.
Could you please write here a general approach to solving my problem?

[javat33489]

Okay, let's do it in Ls-Dyna first:

How to calculate fatigue in LS-Prepost so as to understand how the teeth will get tired after 1000 meters or 2000 meters?

Briefly write the methodology or what cards should be used? I'll figure it out later.

Encode is a complex program - this will be the second episode and I will write a new question about it on the forum.

HELP PLEASE.

[Ashish Khemka]

Hi,

I am not an expert in this field but please wait for other forum members to comment.

Regards,

Ashish Khemka

[Ashish Khemka]

In addition, please see if the following information helps you:

To calculate fatigue in LS-PrePost, you can use the fatigue analysis method provided within the tool. You would need to select the appropriate fatigue definition type, stress value type for the S-N curve, and apply the stress scale factor for S-N curve ordinates. Additionally, you can define different fatigue settings using the provided buttons in the NVH Dialog of LS-PrePost [1]. URL: [1] https://ansyshelp.ansys.com/Views/Secured/corp/v232/en/lsdyna_prepost/lspp_ug_app_nvh.html

For calculating tooth fatigue in Ansys ncode Workbench, after setting up material properties and load using Material Mapping and Load Mapping, you can solve the model for fatigue life. Ansys Mechanical Fatigue Tool uses Solution Combinations to calculate fatigue life for time step loading, utilizing specific equations for alternating stress and mean stress [3]. URL: [3] https://ansys13.ansys.com/KnowledgeArticles/Phase-2A/2054180/2054180.pdf#page=4

Please note that the D3plot file from LS-DYNA can be used in the process, as it contains the necessary simulation results that can be analyzed for fatigue.

 

Regards,

Ashish Khemka

[javat33489]

Yes, I know how fatigue analysis is performed. I already ran it, everything is ok. I now need to scale it for longer.
As I already wrote in my calculation in LS-DYNA, I drilled a 10 mm die with a drill, I received fatigue data, I used the CH curve. And now, based on these fatigue data, I need to understand how long the drill will be able to drill, to understand how many mm it will still last, for example, 1000 mm or 2000 mm. Now I need to somehow scale the fatigue data for further operating time.

[javat33489]

Sir. If what I say cannot be done using a fatigue analysis, maybe a wear analysis can be done? You don't need a SN curve for wear, right?

[javat33489]

It would be much easier if my fatigue analysis showed cycles. I would just understand how many such cycles my part will last for. But they are equal to zero. Explain again why?

[javat33489]

Help please

[Ashish Khemka]

Hi,

My apologies for no response but I do not have expertise in this area. Please wait for other forum members to chime in.

Regards,

Ashish Khemka

[Ushnish Basu]

 

 

Are you using time-domain or frequency-domain fatigue? Please make sure to use a recent version of LS-DYNA and LS-Prepost as those will also show a “Counted cycles” entry, though “Expected fatigue cycles” seems to be zero for time-domain fatigue – I believe it is meaningful only for frequency-domain analysis. You can also look at the cumulative damage ratio to see if there is enough damage for a particular number of cycles