Frequency Analysis

April 2010

Frequency analysis investigates a vibration or time varying signal to identify its fundimental frequency components.  Analyzing the frequency spectrum can identify significant and problematic individual cyclic forces/inputs that are contributing to an instability or reliablilty problem.  Frequency analysis is commonly used in vibration analysis to detect bearing failures, alignment problems, out of balance, gear condition.  However, it can also be used to identify causes of fatigue failure, resonance, and inefficiencies caused by a process input or external force.

Example of a time wave form from a strain gauge analysis of a drive shaft.

Example of a frequency spectrum of the above time wave form with the significant frequencies identified.

Mainstream Engineering utilizes FFT transform software to assist in the generation of a frequency spectrum from a time wave form.  We then identify excitation frequencies to determine their causes and develop solutions for their removal, reduction or isolation.

Typical applications of Frequency Analysis are:
  • Troubleshooting process or machine instability
  • Condition based monitoring
  • Vibration and acoustic noise testing