Hello,
i have a problem that i need to solve, but i don´t know how, any help from anyone would be great
The problem is; in the top of a metallic tower is installed a radar antenna wich weights 170 kgs the hellix and about 230 kgs the motor.
The antenna is fixed to a metallic profile place in the geometric center of the tower, the antena and motor are excentric in the yy direction, the distance between the center of gravity of the tower and the center of rotation of the antenna is aprox 171.84 mm, and 5 mm in the xx direction.
The antenna rotates in the maximum at 60 rpm, about 2*pi rad/s.
Due to the excentricity i found a formula to calculate the FS, ( free force), wich is given by, FS=Mr x ω x e; eurocode 1 parte 3, pag 39
MR mass of the rotor
ω  angular velocity
e excentricity
I´m don´t know wich is the mass of the rotor is the mass of the antena + motor 400kgs?
In this case, because the antenna is excentric there is a precession movement. The angular moment of the antenna is constant given by I . ω;
the torque r x mg, the velocity of the movement is given by r x mg/I.ω rad/s.
If the angular velocity of the antenna diminush the angular velocity of precession incresses.
Is there any way, to calculate the magnitude of force of the precession induce in the tower?
Is the precession neglectable in this case( the antenna rotating induces considerable oscilation of the tower in the reallity)?
Wich equilibrium of forces is the more accurate, to quantify the forces induced by the antenna?
Thanks,
i have a problem that i need to solve, but i don´t know how, any help from anyone would be great
The problem is; in the top of a metallic tower is installed a radar antenna wich weights 170 kgs the hellix and about 230 kgs the motor.
The antenna is fixed to a metallic profile place in the geometric center of the tower, the antena and motor are excentric in the yy direction, the distance between the center of gravity of the tower and the center of rotation of the antenna is aprox 171.84 mm, and 5 mm in the xx direction.
The antenna rotates in the maximum at 60 rpm, about 2*pi rad/s.
Due to the excentricity i found a formula to calculate the FS, ( free force), wich is given by, FS=Mr x ω x e; eurocode 1 parte 3, pag 39
MR mass of the rotor
ω  angular velocity
e excentricity
I´m don´t know wich is the mass of the rotor is the mass of the antena + motor 400kgs?
In this case, because the antenna is excentric there is a precession movement. The angular moment of the antenna is constant given by I . ω;
the torque r x mg, the velocity of the movement is given by r x mg/I.ω rad/s.
If the angular velocity of the antenna diminush the angular velocity of precession incresses.
Is there any way, to calculate the magnitude of force of the precession induce in the tower?
Is the precession neglectable in this case( the antenna rotating induces considerable oscilation of the tower in the reallity)?
Wich equilibrium of forces is the more accurate, to quantify the forces induced by the antenna?
Thanks,
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