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

Equivalency of random vibration and sinusoidal vibrat ion

Equivalency of random vibration and sinusoidal vibrat ion

Equivalency of random vibration and sinusoidal vibrat ion

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]


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
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! Already a Member? Login


Research Report - How Engineers are Using Remote Access
Remote access enables engineers to work from anywhere provided they have an internet connection. We surveyed our audience of engineers, designers and product managers to learn how they use remote access within their organizations. We wanted to know which industries have adopted remote access, which software they are using, and what features matter most. Download Now
eBook - Managing the Context of Product Complexity Using the Digital Twin
Keeping track of changes to complex products is difficult—think Aerospace & Defense equipment, new generations of commercial aircraft, and software-based automobiles. A new way to managing the digital context of the physical product is required and the answer is the Digital Twin. This ebook explores the opportunity available for Operations and Maintenance for the Digital Twin. Download Now
White Paper - Trends in Industrial Filtration
Substantial progress has been made in filtration technologies in recent years. New filter media materials, designs and processes have led to filters that are more efficient, reliable, compact and longer lasting. This white paper will discuss the various trends that are impacting operational responsibilities of MROs today and the resources that are available for staying up-to-date on the latest filtration solutions. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close