Antenna Dia 19.0mm x 720mm Long Wind Vibration
Antenna Dia 19.0mm x 720mm Long Wind Vibration
(OP)
I have a Car Mounted Antenna Dia 19.0mm x 1mm Wall x 720mm Long which creates a vibration at approx. 80km/h. The Antenna has a fibreglass thin walled structure. I believe the vibration is due to the natural frequency of the material.
Can the velocity be calculated to determine critical speed where natural frequency affected?
Can this be designed out ie. longer/shorter length, increase in stiffness, etc...?
Can the velocity be calculated to determine critical speed where natural frequency affected?
Can this be designed out ie. longer/shorter length, increase in stiffness, etc...?





RE: Antenna Dia 19.0mm x 720mm Long Wind Vibration
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: Antenna Dia 19.0mm x 720mm Long Wind Vibration
OK, so it is vertex shedding behind the antenna. This only occurs at 80km/h and up. How can this be designed out.
RE: Antenna Dia 19.0mm x 720mm Long Wind Vibration
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: Antenna Dia 19.0mm x 720mm Long Wind Vibration
How can the frequency and vortex shedding be calculated?
RE: Antenna Dia 19.0mm x 720mm Long Wind Vibration
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: Antenna Dia 19.0mm x 720mm Long Wind Vibration
Hopefully I can relate the frequency back to Velocity and might nearly be there.
Also relation of phsical properties and there effect.
RE: Antenna Dia 19.0mm x 720mm Long Wind Vibration
RE: Antenna Dia 19.0mm x 720mm Long Wind Vibration
I like the idea of the helical vortex breaker. A wire wound around the OD in a helical form could do the trick and would look OK.