×
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

standard methods for sound damping

standard methods for sound damping

standard methods for sound damping

(OP)
Hey!
We developed a material for reducing the sound level. the material, in the form of a sheet, will be kept in between two metallic sheets.We would like to know how much sound it dampness. As we have to supply it to some automotive industries, we would like to have the standard method to determine the amount of sound it dampened.  can anybody tell me the standard procedure to do it? or any standards available on it.

thanks
pmsrao

RE: standard methods for sound damping

There are a few industry standard methods.

The real standard is to measure the sound transmission loss (STL) in an STL suite. The SAE probably has a standard for this.

Another standard is the use of an APAMAT machine that throws ball bearings at a sheet of treated steel, and measures the resulting noise.

However, neither of these gives any more than a rough guide to the performance of your system (a constrained layer damping material) in a specific application.

Why not ask your customers what tests they'd like done?

Cheers

Greg Locock

RE: standard methods for sound damping

For sound transmission-loss, the "standard" method would be the ASTM E90;  other customers such as Ford and General Motors have their own variations on this basic test.
For a constrained-layer damping material, though,  perhaps what you want to do is to measure the loss factor at various frequencies, i.e., the bandwidth at the half-power points divided by the resonant frequency.

RE: standard methods for sound damping

(OP)
This particular application dooesn't typically figure into STL for Auto, as the double layer will never completely cover say the floor pan.  This system called constrained layer damping is used to increase mass, stiffness, and convert dynamic energy into heat in the areas such as footwells and rear wheelhouse.  The proper
test for this is the Oberst bar method.  Not sure of the standard for the test but it ends up getting post processed with ASTM E768.  Pranab Saha of Kolano & Saha is your best bet for an expert to contact in this arena.

Hope this helps,

Eric

RE: standard methods for sound damping

Well, since Rao said "we would like to have the standard method to determine the amount of sound it dampened," I assumed he was referring to sound attenuation, not vibration damping (and not, of course, to getting sound wet).
Thus the reference to the STL testing.
Mr. Saha would refer you to an Oberst Beam test,  but this doesn't necessarily tell you what you want to know if for example, you're trying to reduce sound transmission through a firewall.  

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