Vibration profile

[bcg444]

Hi All,

I am trying to define appropriate duration for the qual test for our equipment. The duration should represent the life cycle of the unit. I have some field data and, of course, profiles from different standards (810, SAE 1455).
My question is: do the profiles for random vibration in 810, for example, represent real environmental data or they are recomended profiles for accelerated test?

Thanks a lot!

 

[mechengdude]

I do not beleive the random vibration curves in 810 are from "real" data. 810 recommends you use real data if avaiable. If not they give various curves for tracked vehicles, air craft etc. that represent approximations of various operating environments.
I also beleive that these curves do not represent HALT levels. HALT levels are usually above and beyond what is seen during its normal lifetime. The HALT is meant to identify weak points in the design. Its not a pass/fail test.

You may want to post on the "military" forum here to get some more detailed answers.

Just as a point of reference I have used 810 curves or similar in the past and never seen a test go more than three hours per axis.

 

[tomirvine]

I agree that you need to gather you own field measurements.

You may want to search out the references that MIL-STD-810F gives, but clear answers regarding the origins of test levels are sometimes hard to come by.

MIL-STD-810F gives some duration guidelines. For example, the exposure duration for the Truck transportation over U.S Highways is 60 minutes per 1000 miles. (MIL-STD-810F, Method 514.5, Annex A, Section 2.2.1)

Furthermore, MIL-STD-810F has some fatigue formulas which can be used to calculate an accelerated test level.

See for example the equations in:

MIL-STD-810F, Method 514.5, Annex B, Sections 2.2 and 2.7.3.

A number of assumptions must be made in using these formula.

Tom Irvine

http://www.vibrationdata.com