drillmaggot.
We have lots of experience in specifying proper noise control systems for wide range of applications, but have not done design for an acoustical louver before. Typically acoustical louvers do not provide substantial noise reduction, and other means of reducing the noise may be...
Why don't you just rent a spectrum analyzer and be done!
Trying to develop your own system/methodology for analyzing dynamic signals can be time-consuming, and at the end of the day you have to make sure that your measurements and analysis are accurate (e.g. calibrated).
Contact the Modal...
Steel spring isolators from Mason Industries have roughly the same stiffness in both the vertical and transverse directions.
Andrew Gorton, MSc
Noise & Vibration Consultant
www.PapadimosGroup.com
The amount of analysis to some extent depends on what you are isolating and where the forces are coming from.
For mechanical equipment in buildings, efficient vertical force isolation is typically the most critical. A good rule of thumb is the isolator natural frequency should be 10 times less...
Are you really "sampling" at 25Hz, or are you referring to the frequency resolution? Fsamp=25Hz is not fast enough for the frequencies you are talking about.
I could see how the lower peak might be due to aliasing, but not the higher one.
Andrew Gorton, MSc
Noise & Vibration Consultant...
I believe you need to have two different time histories, one delayed with respect to the other. This is one of many things that SAP cannot handle.
Andrew Gorton, MSc
Noise & Vibration Consultant
www.PapadimosGroup.com
Hydtools. I'd go look at some acoustics and noise control books, your summary is off.
Andrew Gorton, MSc
Noise & Vibration Consultant
www.PapadimosGroup.com
NRC and dBA are two totally different types of acoustical descriptors. Your spec may be referring to NC (Noise Criteria), which is related to dBA.
Andrew Gorton, MSc
Noise & Vibration Consultant
www.PapadimosGroup.com
Does anyone know of a method for calculating the bending stiffness of metal decking with concrete in both directions? I have some ideas, which seem reasonable, but I would like to find a formal method to "hang my hat on"...any thoughts?
Andrew Gorton, MSc
Noise & Vibration Consultant...
Here's one paper on TMD applications.
Andrew Gorton, MSc
Noise & Vibration Consultant
www.PapadimosGroup.comhttp://files.engineering.com/getfile.aspx?folder=a53676c5-4c91-4d9c-ab4e-9a0e3204676a&file=Hanagan_Linda_M.pdf
You should have the manufacturer provide you with vertical and horizontal polar plots for these speakers.
Andrew Gorton, MSc
Noise & Vibration Consultant
www.PapadimosGroup.com
Yes the walking harmonics are really there and do contribute to the actual response.
There are more advanced methods parameter estimation techniques for estimating the poles of the FRF function, but looking at the imaginary plot is a good start.
Andrew Gorton, MSc
Noise & Vibration Consultant...
I think you are correct if you are talking about global modes for an entire floor plate; I was speaking to local modes within a single bay.
I'm wondering though if these global modes will truly participate in the response once "sees" within a single bay (i.e. a driving point response).
It...
I'm not so sure about the increased slab thickness decreasing vibrations drastically.
Very lightly loaded floors tend to have high vibration levels, so more mass in the slab could be beneficial (possibly more stiffness as well); however more mass decreases the natural frequency which could...
