The RC Design Functions spreadsheet has now been updated to Version 9.06, and is available for free download from:

RC Design Functions9.zip

The new version fixes a problem with the MomcurveTS function, which was returning an error for any input strain greater than 0.0005. An example of the updated function is shown in the screenshot below:

For more details of how the function works, and how to use it, see: https://newtonexcelbach.com/2015/10/13/solving-non-linear-equations-with-two-or-more-unknowns-4/