I’m trying to get the acceleration information of the tower-top. I found there is an output of YawBrTAxp which could generate this information.However, I didn’t find the YawBrTAxp in my Test.ED or Test.outb files. Thus, I’m wondering how I could add YawBrTaxp to my requested outputs. Another question is that the acceleration YawBrTAxp give is the absolute value. Is it possible for me to get the true value of the acceleration?
YawBrTAxp is an output of the ElastoDyn module, so, you should add it to the output section (OutList) of the ElastoDyn primary input file before running FAST.
I’m not sure what you mean be “true acceleration”, but by “absolute”, we mean that the YawBrTAxp is the acceleration relative to the inertia frame (as opposed to, say, relative to the tower base). The only term missing from YawBrTAxp that would be measured with an accelerometer is the fixed gravity term, -g directed downward, which we account for in FAST through structural weight, etc., but don’t specifically track in the structural acceleration.