Potential strain energy change based damage indicator

• Commonly known that for a timeshenko beam the strain energy,

(15.6)

• Clear relation between the strain change and the second derivative of every mode shape
• Natural frequency change,depending on a damage location along the beam length.

(15.7)

Hybrid Damage Detection method (HDD)

• Utilizing natural frequencies and mode shapes for fatigue damage detection

  Experimental set for data gathering

• Mode shape are sensitive to damage
• Mode shapes have been obtained experimentally
• To obtain the modal parameters
• Frequency Response Functions (FRFs) via Fast Fourier Transformation
• Determination of natural frequencies by finding local maxima in averaged FRF graph
• Those frequencies have been examine ODS (operational deflection shapes).