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E
ebelmonte1-Visitor
1-Visitor
March 5, 2018
Question

2d linear interpolation

  • March 5, 2018
  • 1 reply
  • 4292 views

Dear all,
I'm facing again a problem with linear 2D interpolation.
In this case I tried to see if the results of direct and inverse interpolation coincide.
z=f(x,y) and y=f(x,z).
Unfortunately, they don't.
Could you please help me in finding the solution of this problem?
Attached you see the mathcad file.

Thank-you very much for your support.

Regards.

Enrico

1 reply

W
Werner_E25-Diamond I
25-Diamond I
March 5, 2018

Sorry, but I see no reason why the two diagrams in your sheet should coincide.

Your first table yields a value for cycles  of 35309 if force=16574 and ratio=0.2.

Your second table suggest a cycle value of just 100 for the same values. Obviously different functions.

 

E
ebelmonte1-VisitorAuthor
1-Visitor
March 6, 2018

Dear Werner,

 

Thank-you very much for your reply.

You are right. I've sorted out the file. Now it should be clearer.

I still find some difficulties by interpolating the data.

I really appreciate your support!

 

Regards.

 

Enrico

 

E
ebelmonte1-VisitorAuthor
1-Visitor
March 7, 2018

Dear Werner,

 

The discrepancies are possible since a low variation of the stress can lead to a big variation of the number of cycles.

The S-N curves are linear if x- and y-axis are logarithmic.

I think that the data are too much apart from each other for linear interpolation.

 

I tried also the following interpolation

woehler_law.PNG

 

which is working better for low number of cycles but poor for high number of cycles.

Do you have any idea how I can deal with this issue?

Thank-you very much!

 

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