tracked vehicle vibrations 2

[izax1]

Not much response on mechanical on this one, so I try here

I assume my main vibration input to my tracked vehicle (defence)innstalled equipment will originate from the tracks traversing a paved road. Of course, we want to install the equipment on as many vehicles as possible. (The sales people will take care of that!)Does anyone know of the vibration levels generated by these vehicles. Specifically: Are the frequencies generated by these vehicles very different? (Like Abrams, M113, Bradley, Leopard etc.) Are the vibrstion levels generated very different. My question really turns down to: Will I have to design for all the different vehicles, or is there a common vibration spec for this type of platforms?

Thanks for any help.

 

[KENAT]

Some time back I was involved in designing some racks for storing guided missiles in various armored personnel carriers. One of the questions I asked of the vehicle design authorities was about vibration and I didn't get a very definitive answer.

MIL-HDBK-767 (available on the net) has some information on 'noise' but not sure it quite meets your needs.

Mil-std-810 (also on the net) might be of use but I don't think will have the explicit info you ask for.

Not sure about your tracks on paved road assumption.

You may want to try contacting one of the vibration test houses that may have information.

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[izax1]

Thanks KENAT. I have been looking through MIL-STD-810, but that does not give any specific infomation. Just test procedures etc. I have some numbers from tests on M113, but I don't know if that is relevant for the other vehicles.

 

[IRstuff]

You don't need specific information. If you can meet the vibration and shock requirements in 810, you're essentially good to go.

TTFN

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[KENAT]

Does 810 actually giver requirements as such?

It's been a while since I looked at it but I wasn't sure if it did or if it gave spectrum to test against. It may seem a bit tomato/tomatoe but I seem to remember actual requirement specs only calling up certain tests or portions of tests etc.

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[IRstuff]

Of course it does; that's its whole purpose. There may be vehicles that are either outside of 810's limits, or simply want to do their own thing, but standard vehicle and transport vibration is well defined.

TTFN

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[KENAT]

That's what I couldn't remember - how much detail it gave on applicability of the test spectra.

I remember having 'generic' aircraft stores spectra etc. and I just wasn't sure if there was similar specifically for tracked vehicles.

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[izax1]

I still can't find any specific requirements for tracked vehicles. Fig 514.6D-8 only gives a representative spectrum (random on random). In fact, the 810G states: "Because the track pitch and the mechanical vibration transmission path through the vehicle are unique to each vehicle, vibration amplitudes and frequencies are vehicle and location dependent."

It then refers to ITOP 1-1-601, which will give tested values for M109, M110 and M113. That's all I can find in 810.

 

[ornerynorsk]

Sounds like this is for detection and recognition. No offense izax1, may I ask what country?

 

[izax1]

Probably the same as you. Norge

 

[RickNie]

Are you going to use vibration isolators? If so, the most important question is what will be the max shock event. Use the fragility level of the equipment you are trying to protect as a base, then take into account the max shock input, consider the max deflection room, and calculate the necessary isolator frequency. The system natural frequency should be such that it does not matter what the inputs are if you design your system under it. You will be well into the isolation region anyway.

 

[izax1]

No, we will not be able to use vibration isolators. It is actually not shock that is the prime concern. It is rather vibration fatigue.

 

[loki3000]

offtopic
kenat, if i remember correctly you said somewhere that you were from uk. were you by any chance (from your post) employed by BAE and if so may i ask why did you quit? because more and more work is being transferred to the US?

 

[boo1]

Tracked vehicle vibration is typically low level broadband random vibration with high level narrowband random vibrations at the resonant frequencies of the tracks at various vehicle speed increments. Don't forget to consider the transportation induced vibrations (Truck, rail, ship, ect.)

The M113 is considered to have the most severe vibration environment of all U.S. Army tracked vehicles. The track-sprocket wheel reaction and the track-idler wheel reaction are the chief sources of vibration. For tracked vehicle vibration consider; MIL-STD 810F, Method 514.3 Category 1.

In this forum we can't post the measured response data.

Slope of a log/log fatigue or S/N curve
– Per MIL-STD-810F:
• Many materials exhibit exponents between 1/6 and 1/6.5
• Wide variation based on degree of conservatism desired as well as material properties
• Sophisticated analyses based on fatigue data (S/N curves)
for specific materials should be used when practical

 

[KENAT]

No I was not employed by the former British Waste of Space. I moved to the US for personal reasons.

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[mechengdude]

For tracked vehicles MIL-STD-810 refers you to a seperate standard for tracked vehicles. The vibration curve is random on random. The specification is ITOP - International Test Operations Procedure 1-2-601 Laboratory Vibration Schedules.

If you are designing for a specific customer they should supply the requirement. If you are designing a product on your own dime to put on multiple vehicles, qualify it to teh "worst" vibration specification and then do a qualification by similarity for other platforms.

 

[izax1]

Thanks a lot mechengdude. Yes the ITOP 1-2-601 gave a real clue, and also gives some useful information on how to get data with other carriers. Also, I found ITOP 1-1-050 very helpful.

Thanks again.

 

[loki3000]

i was looking at some career ads over there and i saw some that were interesting (stress analyst; i'm just a beginner though). so i take it that that's not a wise choice?

 

[ChamberQueen]

izax1, I am currently working on some projects with the 810 group. I can tell you that they would direct you to find measured data if at all possible, and that the data will definitely be different between various makes of tracked vehicles, and the sentence you quoted from 810G backs that up.

You can always do your testing to assumed "worst case scenario" but your best bet is to get some input on the levels. If you have to qualify your materiel according to a contract it may be stated there. Good luck.

 

[izax1]

Thanks ChamberQueen.

We have done some tests on the CV90 (from BAE/Hägglunds), but we cannot tell if it representative for other vehicles. We are specifically interested in the vibration pattern on the Abrams vehicle.
Do you know of any data available?