Table of Contents
Fast Fourier Transform (FFT) spectra are essential tools in structural health monitoring (SHM). They help identify changes in a structure’s dynamic properties by analyzing vibration data. Proper interpretation of FFT spectra enables early detection of damage or deterioration.
Understanding FFT Spectra
FFT converts time-domain vibration signals into frequency-domain data. The resulting spectrum displays the amplitude of vibrations at different frequencies. Peaks in the spectrum indicate dominant natural frequencies of the structure.
Interpreting Spectral Features
Changes in the FFT spectrum can suggest structural alterations. A shift in natural frequencies may indicate stiffness loss, while the appearance of new peaks can signal damage or added mass. Consistent monitoring helps distinguish between normal variations and significant changes.
Practical Tips for Analysis
- Baseline Data: Establish a reference spectrum during healthy conditions.
- Regular Monitoring: Collect data periodically to detect trends.
- Peak Identification: Focus on prominent peaks related to fundamental modes.
- Compare Spectra: Look for shifts or new features over time.
- Correlate with Other Data: Use additional measurements for confirmation.