I am new to vibration analysis and have scoured the internet to find how to read acceleration and then transform it into a time domain plot of velocities, like inches per second and display over a period of time, like 5 seconds. All the sites show the calculus to take integral of acceleration over time, but I have discrete values at time t0 through tN for 5 seconds of reading at a fixed rate t. I assume I need to read the accelerometer G values at a rate twice the frequency of resolution I want to capture time based waveform data. Once I have this array of G values, how do I transform it into a time domain plot of velocity -vs- time?
To obtain velocity, numerically integrate the acceleration values, after subtracting the acceleration due to gravity. In general there will be components of g along each of the accelerometer axes. In the simplest, least accurate method (Euler integration) the basic equation for the x axis, starting from Vx=0, is:
Vx = Vx + Ax*deltat;
The main problem with this approach is the inability to accurately subtract the components of g from each of the axes. You need to know the 3D orientation of the accelerometer quite precisely to be successful (to better than 0.1 degree), or the calculated velocities will increase indefinitely.
On the other hand, for peak acceleration Ax , then for a sinusoidal vibration of frequency f, the peak velocity Vx = 2PIf*Ax