Continue to Site

Eng-Tips is the largest engineering community on the Internet

Intelligent Work Forums for Engineering Professionals

  • Congratulations pierreick on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

How to derive the first natural frequency requirement of a subassembly?

Status
Not open for further replies.

Ionut Cosmin

Aerospace
Jul 22, 2016
24
Hello all,

I am trying to determine what should be the first eigen mode frequency for a subassembly if the requirement is known for the assembly.

For example, let' say I have a robotic arm which has a requirement that the first natural freq should be higher than 70 Hz. On this arm I have an equipment, let's say a camera. How do I determine the requirement for minimum freq of the camera? is there an equation that can provide this answer? or should I just take the same requirement from the main assembly, the arm?

Thanks,
Cosmin
 
Replies continue below

Recommended for you

While it would be expected that the camera's modes would be >70 Hz, the main effect is its mass on the bending mode of the arm. 70 Hz seems incredibly high, perhaps that is driven by the camera.



Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376
 
both the camera and the assembly have to have first natural freq > 70 Hz. if the first mode of the camera is ~ 70 Hz, you will likely have difficulty with the assembly frequency.
 
The alternative is to put the assembly or the camera on isolators and/or stabilization system; the US Army used to have an EO sensor mounted on the rotor shaft and it had 8-Hz isolators, and coupled with its active stabilization servos could maintain nearly undetectable vibration levels, at least, good enough to kill Iraqi tanks from a looong distance

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! faq731-376 forum1529 Entire Forum list
 
Status
Not open for further replies.

Part and Inventory Search

Sponsor