the parameters of Strain in blades and tower

Dear Jonkman,
when I searched the keyword “strain” in the OutListParameters file, it seems to that there is only the strain of the shaft and rotor. In the forum, I found that ElastoDyn.dat may own these parameters. What’s the meaning of TwrGagNd and NBlGages? How to get the output of strain in blades and the tower? Thank you.

Best regards
Gaoshuai WANG

---------------------- OUTPUT --------------------------------------------------
True SumPrint - Print summary data to “.sum” (flag)
1 OutFile - Switch to determine where output will be placed: {1: in module output file only; 2: in glue code output file only; 3: both} (currently unused)
True TabDelim - Use tab delimiters in text tabular output file? (flag) (currently unused)
“ES10.3E2” OutFmt - Format used for text tabular output (except time). Resulting field should be 10 characters. (quoted string) (currently unused)
0 TStart - Time to begin tabular output (s) (currently unused)
1 DecFact - Decimation factor for tabular output {1: output every time step} (-) (currently unused)
0 NTwGages - Number of tower nodes that have strain gages for output [0 to 9] (-)
10, 19, 28 TwrGagNd - List of tower nodes that have strain gages [1 to TwrNodes] (-) [unused if NTwGages=0]
3 NBlGages - Number of blade nodes that have strain gages for output [0 to 9] (-)
5, 9, 13 BldGagNd - List of blade nodes that have strain gages [1 to BldNodes] (-) [unused if NBlGages=0]
OutList - The next line(s) contains a list of output parameters. See OutListParameters.xlsx for a listing of available output channels, (-)

Dear Gaoshuai,

The ElastoDyn module of FAST / OpenFAST does not output strain directly; rather, ElastoDyn can output deflection at a node. The term “strain gage” is used simply to mark a node in ElastoDyn where response outputs (deflection, sectional loads) can be output.

The definitions of TwrGagNd, etc. have been discussed several times on this forum, e.g., see:

Best regards,