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Vibe Input, Random or Sine?

Vibe Input, Random or Sine?

Vibe Input, Random or Sine?

(OP)

The following vibration spec came across my desk almost on a cocktail napkin.  

Vibration/ Shock Spec:
Frequency Range:  10Hz to 40Hz; amplitude = 0.1" p-p
                  40Hz to 2000Hz; acceleration = 4g RMS
Frequency Period: 30 minutes; 10Hz to 2000Hz and return
Test Time:        3 hours per axis


My job is to work with a test house to carryout this test. I'm assuming this is not a Random Vibe Test as the Amplitude is not specified in g^2/Hz, am I correct?

Thank you in advance for any advice.
-Tom
 

Failure is a prerequisite of successful design

RE: Vibe Input, Random or Sine?

If it is random vib, be safe and just ask for the break point table.  

Tobalcane
"If you avoid failure, you also avoid success."
"Luck is where preparation meets opportunity"  

RE: Vibe Input, Random or Sine?

(OP)
This is a situation where the customer did not require a spec, but the sales engineer wanted some piece of mind that the product would endure application environment. This aforementioned vibe spec is a spec that he used a while back to test another product for a seperate,but similar type of customer (heavy outdoor vehicle equipment e.g cranes).

With the minimal experience/knowledge I have of vibration testing I would agree with GregLocock and figured that it was a Sine Sweep from this part of the spec:
"Frequency Period: 30 minutes; 10Hz to 2000Hz and return", Random vibe excites all frequencies at once, right?

"40Hz to 2000Hz; acceleration = 4g RMS"
Are the amplitudes of Sine Sweeps typically given in g RMS?

  

Failure is a prerequisite of successful design

RE: Vibe Input, Random or Sine?

We see a lot of questions like this here and I just don't get it. If the spec is ambiguous then do a sanity check yourself (just to make sure you aren't being stupid), ask a colleague to do the same (or ask here if there is no-one else); then go back to the specifier and get clarification.

Simples

M.

--
Dr Michael F Platten

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