×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Equivalency of random vibration and sinusoidal vibrat ion

Equivalency of random vibration and sinusoidal vibrat ion

Equivalency of random vibration and sinusoidal vibrat ion

(OP)
It is recognized that there is no "real" equivalency between random vibration and sinusoidal vibration. However, are there are any empirical equations based on tests or analysis that provide "approximate" equivalency between random vibration and sinusoidal vibration ?

RE: Equivalency of random vibration and sinusoidal vibrat ion

You can measure the average RMS of the random signal and then use 1.414 for the value in 0-pk at the dominant frequency.

RE: Equivalency of random vibration and sinusoidal vibrat ion

Lunney & Crede (see WADC TR-56-503) showed that by assuming Rayleigh distribution of the peak accelerations and combining this with Miner's rule of equivalent damage, the equivalent sinusoidal response acceleration, Aeq is given as

Aeq = Q*Ar

where Ar is the RMS random vibration response acceleration

and Q=[(0.5*(2pi)^.5)^(1/(lambda*alpha))*(lambda*alpha/e)^0.5]

where

lambda = a constant based on experimental data
alpha = slope of the fatigue curve when plotted in log-log coordinates
e = 2.718281828...

Long story short, Q = 2.14-2.17 (usually taken to be 2.14) for most metals.

Jeff Strain
jeff.strain@padtinc.com
Phoenix Analysis & Design Technologies

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources