ALMA Wind Random Vibration Analysis of legs • In the ESO-AEM TM No. 40 was reminded that there aren't any information if wind induced deflection and/or von Karman vibration may be excluded on slender legs. • To treat this aspect we intend to compute the deflections by a wind random vibration analysis using the random spectral content defined in the Simiu spectrum, S(u), see next slide. • Wind pressure random loads (Pa^2/Hz) will be derived from the Simiu spectrum (m/s)^2/Hz and applied over the most sensitive surface structures. • Worst case random response analysis will be performed on the Antenna FEM to determine the structural response to dynamic wind loading and the resulting optical errors.
ALMA • Random Vibration Input