
Re: Sine on Random Vibration analysis
Anthony Botting Oct 14, 2013 8:05 PM (in response to Yuvaraj Dhanasekar)Yes you can do that. You need the "Linear Dynamic" analsysis package. I believe it comes with what is called "Simulation Professional", but check with your VAR.

Re: Sine on Random Vibration analysis
Anthony Botting Oct 14, 2013 11:49 PM (in response to Anthony Botting)Yes the "sine on random" is a commonly deployed test technique. You can calculate the energy input from the sine function (or a summation of several known excitation frequencies), then combine the energy levels to the random source (linearity allows principle of superposition to hold for this case). Then you can use the "Random vibration" analysis option in SW Simulation.

Re: Sine on Random Vibration analysis
Jared Conway Oct 15, 2013 12:47 AM (in response to Anthony Botting)Good to know. My experience is that those curves are just referred to as random vibration curves. When a sine is involved, either harmonic or time history is usually called for.
But definitely sim prem.

Re: Sine on Random Vibration analysis
Yuvaraj Dhanasekar Oct 15, 2013 12:52 AM (in response to Anthony Botting)Hi botting..
can you share me the procedure to do so??....any docu such kind..??
Re: Sine on Random Vibration analysis
Jared Conway Oct 15, 2013 12:59 AM (in response to Yuvaraj Dhanasekar)Which part? The sine to random or setting it up in solidworks simulation?

Re: Sine on Random Vibration analysis
Yuvaraj Dhanasekar Oct 15, 2013 1:03 AM (in response to Jared Conway)The sine to random ...





Re: Sine on Random Vibration analysis
Jared Conway Oct 14, 2013 9:02 PM (in response to Yuvaraj Dhanasekar)do you have a copy of the standard?
sine and random vibe don't really go together from my experience.
but anthony is right, if you have a dynamic analysis, you need a higher level of solidworks, solidworsk premium. if you dont' have that license, drop me a line at jared@hawkridgesys.com, we can help you with that analysis. if you have the license but need a push in the right direction, we also offer training and mentoring on those analyses.

Re: Sine on Random Vibration analysis
Yuvaraj Dhanasekar Oct 15, 2013 1:01 AM (in response to Jared Conway)Hi jared,
I am from VAR too..:). Sine on RVA can be done in solidworks simulation premium.
In Sine (harmonic) analysis we give acceleration vs real time as the input...In RVA we give acceleration2/hz vs frequency as input.....
How to combine these two to do Sine on RVA.
I hope Anthony has got answers..

Re: Sine on Random Vibration analysis
Anthony Botting Oct 15, 2013 4:06 PM (in response to Yuvaraj Dhanasekar)from what I recall you have to convert the sine input to have the same units as the random vibration input, then just add them. I believe you will need to calculate a GRMS power value for each sine frequency and add it to the appropriate frequency band in the GRMS of the random vibration signal. Then, just input the whole band on the loading curve of Simulation. I know that Steinberg's "Vibration Analysis for Electronic Equipment", 1988 (WileyInterscience), has some details about this. Hope that helps.

Re: Sine on Random Vibration analysis
Anthony Botting Oct 15, 2013 5:10 PM (in response to Anthony Botting)as you wrote for sine: you have the acceleration vs time record so you can generate a set of frequency 'bands' where the acceleration is nearly constant, square it, and divide by the bandwidth. You will need some software to sortout (identify) the frequencies into 'bands' which have level (or nearly level) acceleration values.
Example: the band from 1000 to 5000 Hz has fairly const acceleration within some tolerance, say 10 m/s^2, the bandwidth is 4000 Hz and the center frequency point is at 3000 Hz [1000 +(50001000)/2]. So the first point will be: 100/4000 = 0.025 (accel2/Hz) at 3000 Hz. Go up the spectrum from 5001 Hz to say, 10,000 Hz or for as many bands as you can find with nearly const acceleration. I believe you could get some open source software if you look hard enough, or just write your own alorithm to do that.

Re: Sine on Random Vibration analysis
Rick Champagne Jul 26, 2014 1:40 PM (in response to Anthony Botting)True. I have done it the other way  convert random into sine, but from some internet reading it seems most experts say to do it like you are describing, convert the sine peaks into narrow band psd rectangles. Some say to double their value to get closer to a 2 sigma value.


