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Hi @mutricyl, Can you provide some detail on where these new costs come from? Did you use the reference that Ryan sent to develop these coefficients, or another source? Depending on that answer, @RyanDavies19, can you confirm that these coefficients can be included in the newCosts.yaml? More specifically, that they fit with the applications and fidelity of the existing coefficients in the newCosts.yaml? In general, @mutricyl, can you provide additional notes, explanations, or documentation of the source of these values? Stein |
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Sorry for the very badly writen PR. I had prepare some justification but obviously they did not went through Anyway please find below some justifications: MBLMBL is a polynomial regression at the third order of breaking load data from Anchor Marine catalog provided by @RyanDavies19 (pages 52 & 53) MassAs suggested in the comments, and backed by the figures from Anchor Marine same values are used for all grades Axial stiffnessAxial stiffness is derived from DNV-OS-E301 2013 as for R4 grade CostR3 chain cost was already available. For R4 chain cost is identical for studlink and studless so I used the same approach for R3 dvol_dnomUsed the same values than R4 chains assuming same density hydro coeffUsed the same values than R4 Would you like my excel sheet to double check the regressions ? |
| mass_d2 : 21e3 # linear mass density per diameter^2 [kg/m/m^2] - avg R4 studlink and R4 studless | ||
| chainR3 : # R3 grade chain, studless | ||
| mass_d2 : 20.0e3 # linear mass density per diameter^2 [kg/m/m^2] | ||
| EA_d3 : -6.283e07 # stiffness per diameter^3 [N/m^3] |
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Is there a reason that this differs from R4 for studless while it is the same as R4 for stud link?
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mass_d2 is 20.0e3 for studless and 21.9e3 for studlink and is the same for R3 and R4
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Yep, sorry I was referring to the EA values. I left a commend for @shousner below to address it.
| mass_d2 : 20.0e3 # linear mass density per diameter^2 [kg/m/m^2] | ||
| EA_d3 : -6.283e07 # stiffness per diameter^3 [N/m^3] | ||
| EA_d2 : 84.82e9 # stiffness per diameter^2 [N/m^2] | ||
| MBL_d3 : -1.784e09 # minimum breaking load per diameter^3 [N/m^3] |
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Am I correct in reading that other than the EA difference flagged above, the only difference between R3 and R4 is the the MBL curves (which you pulled from the Anchor Marine catalogue)?
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Correct, steel grade only changes MBL and EA
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@shousner I'll let you decide on EA values, thats more your domain. In general though I agree that it should follow what is in the standards.
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@mutricyl overall this looks good, thanks for providing the info. If you could just add documentation in the file header as to where all the values that are different from existing values come from that would be great.
Also, just for housekeeping and documentation for future users, can you share a plot of the regression and source data?
| # - This default yaml uses R4 studless chain as the default style of chain | ||
| # - The chain MBL uses a cubic function, so be aware if you are researching theoretical chains with diameters greater than about 360mm, as the MBL will then decrease | ||
| # - Chain EA values not provided in manufacturer catalogs, so the below coefficients are taken from DNV-OS-E301 2013 | ||
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Please add a comment here documenting the source of the R3 MBL data
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@shousner this looks good to me! I'll let you decide what you want to do on the EA values. I don't remember if you have looked at chain in the past or not when making the original coefficients. |
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