Electronic Back Panel Mounting

[kbujuru]

Hello All,

I am trying to investigate robust methods of mounting electronic back panel inside an enclosure. The backpanel assembly weighs about 170 pounds and is subjected to 10G shock and vibration testing. In the past, we have used the following method
--mounting the panel on the collar studs welded on to the enclosure with vibration dampeners between the panel and the collar studs and ran a threaded bolt from from the front of the panel to inside of the vibration dampener. see attached picture.


However, this method had a failure point at the weld between the collar stud and the enclosure. Therefore my question is, are there any industry standard mounting methods that I can take a lead from?

Any help is greatly appreciated.

thanks
karthik

 

[drawoh]

kbujuru,

This sounds like a general mechanical engineering and design question, rather than one about vibration.

You must know what forces are being exerted on your back panel. You need to analyze each element of your structure to verify that they can take the load. Your materials must be well below their yield stress. You may need to account for metal fatigue. Your fasteners must be well below the rated capacity.

Some other thoughts...
[ol]
[li]Have you engineered your anti-vibration mounts properly? If not, you may be amplifying your vibration, not reducing it. Did you work out the resonant frequency of your mounts?[/li]
[li]Are those red things rubber? If you clamping a piece of rubber between two faces, with a big bolt, you don't have an anti-vibration mount. You have a solid mount that transmits all the vibration and shock. [/li]
[li]What constrains your bolts from shaking up and down? You may be applying a substantial bending moment to the base of your studs.[/li]
[li]Is your material aluminium? Most structural grades of aluminium either are heat treated or work hardened, until you weld them. Surprise![/li]
[li]How badly do you need to shock mount this thing? Sometimes, the best solution is to ruggedize your parts, apply threadlocker, and tighten everything down hard with a torque wrench.[/li]
[/ol]

--
JHG

 

[kbujuru]

drawoh,

Thanks for your thoughts.

1,2.First of all, the red things are rubber, and I agree that the setup presented is not an anti-vibration mount as the dampener is screwed onto a collar stud welded to the back panel-- <sigh>.
3. The bolts aka studs are welded to the back panel and thus, tremendous bending moment at the stud base
4. Material is SS316
5. This is a design of an EE, and I am newly brought into the team as a first ME. To answer your question, honestly I dont know as I didnt witness the test. Like you suggested, I will first ruggedize the parts and then use vibration mounts if needed.

Also, I have come up with a mounting method idea involving unistruts and vibration pads. I am yet to perform the all the bending moment, von-mises stress, and deflection calculations to validate my design. I will share my calculations once they are ready.

thanks again for the prompt response.

Best Regards,
karthik

 

[drawoh]

...
5. This is a design of an EE, and I am newly brought into the team as a first ME. To answer your question, honestly I dont know as I didnt witness the test. Like you suggested, I will first ruggedize the parts and then use vibration mounts if needed.

...

Been there. Done that.

In my case I also did not witness the test. I don't know if they ran it at some vibration state for a specified time period, or if they tested it to destruction.

--
JHG

 

[DubMac]

Have you looked at wire rope vibration isolators? Extremely effective and have been used in military and aerospace for many years for isolating sensitive electronics. Go look at enidine.com.