I have a steady state acceleration signal with acceleration amplitude different frequency with different phase angle.

For example

Frequency  amplitude phase

60Hz            60            179

120Hz          70             120

These are fictitious values I have given as an example

1. I wanted to know how to analyze phase angle got from an fft. As the graph is given figure below?

http://www.mathworks.com/help/signal/ref/angle.html

2. As a whole I want to know how can I represent a time domain acceleration signal accurately in frequency domain. and apply in ANSYS?

3. How do I account for phase lag due to damping?