A Numerical Calculation Method for Galloping and Prevention of it

Study of the axial-torsional coupling effect on a sagged transmission line

“…The Den Hartog theory [1,2] argues that instability occurs when the negative slope of the lift coefficient is larger than the drag coefficient. GoTo and Koike [3] utilize the Den Hartog mechanism to suggest a method for preventing galloping. Ruedy [4] proposed that torsional motion is an integral part of the galloping phenomenon, and its coupling with the transiational motion is responsible for most cases of large amplitude vibrations.…”

“…pre-tensioned string subject to sinsoial load at both ends where p is the density of the string (mass per unit volume). The total force F(x,t) transmitted through any cross section of the string of area A is given by du(3)(4) F(x,t) = AE dx Assume boundary conditions as follows x=0 u=0 x=L/2 AEOu/dz) = P + Qcos2nft = F(L/2,t)Then from Eq. (3-3), it can be readily shown that cosXz(3)(4)(5) F(z,t) = P + Q ---cos2nft cos(XL/2)(3-6) % = 2nf(p/E)i/'It is convenient to introduce the fundamental frequency» fo, for the free longitudinal vibration of the string.…”