Subject: Graphing Problem Mon Sep 24, 2012 2:51 pm
GSIOverlord: How do we graph the damped oscillations from the dynamic test with the curve? We know the max frequency, but we cant figure out how to get the damped oscillation data points to have a curve with it to find the amplitudes of successive peaks.
GSI Overlord Admin
Posts : 126 Join date : 2012-08-30
Subject: Re: Graphing Problem Mon Sep 24, 2012 8:24 pm
I assume you are talking about getting the peaks that you need for the log-decrement method. There's no one 'correct' answer to this, but you will most likely want to program some kind of algorithm using Excel or Matlab that picks off those peaks for you. Think about what mathematically is happening at each local maximum as a starting point for the algorithm. If you can't figure out a way to do it programmatically, you could of course use visual inspection to find the peaks, although the brute force approach would probably take more time.
GSI Overlord Admin
Posts : 126 Join date : 2012-08-30
Subject: Re: Graphing Problem Tue Sep 25, 2012 12:29 am
Actually, it may just be easier for the log-decrement method to do a visual inspection, since you only need two successive, positive peaks. However, if you are trying to fit a curve to all the successive positive peaks, then you'll need a program, I suspect.