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1-Newbie

## Feed result of equation back into itself? How?

Hello,

I've attached my mathcad document and it explains what I am trying to do.

I have two equations, A and B.

Equation A determines the length of a crack in a material specimen after the specimen has been loaded a distinct number of times. This is based on several variables, one of them being the initial length of the crack.

So after one cycle, I can determine how much this crack grew. I can then determine the residual strength of the material based on this new crack size.

What I need to do, is make a plot that has residual strength (Equation B) in the y axis, and number of cycles (Equation A) in the X axis.

The process would look like this:

1 - Equation A calculates the final crack length in the specimen after ONE cycle (given an initial crack length value).

2 - Equation B takes this final crack length and calculates the residual strength.

3 - The residual strength is plotted in the 2D plot.

4 - This final crack length is then fed back into Equation A to determine how much it grows after ONE cycle.

5 - Repeat steps 2-4 until the residual strengh reaches zero.

How can I do this? I appreciate any help!

Attached is the workbook.

1 ACCEPTED SOLUTION

Accepted Solutions
15-Moonstone
(To:Fred_Kohlhepp)
 FredKohlhepp wrote:Alan's done the heavy lifting; I just plotted N vs stress as requested.

Thanks Fred. Perhaps, one day, I'll remember to read the whole question before jumping in!

Alan

9 REPLIES 9
24-Ruby III
(To:ptc-4451268)

You can/must do a complet calculation one time and than repeat it n time by for example copy and paste equations.

Than you can use the while operator!

5-Regular Member
(To:ptc-4451268)

Am I getting confused or are you saying N calculates af?

Solve you do not need to solve for af?

Mike

15-Moonstone
(To:ptc-4451268)

Do you mean something like the attached?

Alan

23-Emerald I
(To:AlanStevens)

Alan's done the heavy lifting; I just plotted N vs stress as requested.

15-Moonstone
(To:Fred_Kohlhepp)
 FredKohlhepp wrote:Alan's done the heavy lifting; I just plotted N vs stress as requested.

Thanks Fred. Perhaps, one day, I'll remember to read the whole question before jumping in!

Alan

1-Newbie
(To:AlanStevens)

Thank you for the help!!! I am going to take a look at this now and see if I can figure out how it is done. At first glance the plots look reasonable.

If I have any questions I will let you guys know.

Thanks again!

1-Newbie
(To:AlanStevens)

Alan,

Do you suppose you could describe what the lines in the program routine mean?

15-Moonstone
(To:ptc-4451268)
 ptc-4451268 wrote:Alan,Do you suppose you could describe what the lines in the program routine mean?

See attached.

Alan

1-Newbie
(To:AlanStevens)

Thanks!

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