Dynamic response analysis using Laser Doppler Vibrometer

Resonant vibration is often a contributory factor of many of the vibration related problems that occur in structures and operating machinery. The resonance of a structure should be identified and quantified to avoid vibration induced cracks and damages to the structure. Further, changes in the physical properties of the structures due to damage alter the dynamic responses such as natural frequencies, modal damping and mode shapes. Laser Doppler Vibrometer can extract vibration signatures for the purpose of damage detection without mass loading of the specimen. It is a non-contact vibration measurement system which works on the principle of Doppler Effect and interferometry. Laser scan heads are capable of measuring movements in all the three orthogonal directions yielding full information of three dimensional movements of the structure. Guided waves such as Lamb waves generated with the help of bonded PZT patches on composite structures can be analyzed for damage detection using Laser Doppler Vibrometer .