Vibration Testing Based on Impulse Response Excited by Laser Ablation (Input Sensorless FRF Measurements)

This paper proposes an innovative vibration testing method for membrane structures based on impulse response excited by laser. Non-contact impulse force is generated by irradiating a high power pulse laser to a structure. The laser excitation makes a precise measurement of the frequency response in wide frequency range possible because an ideal impulse force is applied to a point on the structure. Using a laser Doppler vibrometer to detect a response of the structure, both non-contact laser excitation and measurement are achieved in the vibration testing system. Furthermore, a vibration measurement of the membrane structure in vacuum environment is effectively conducted by using the proposed vibration testing method with a vacuum chamber. The validity of the present vibration testing system is verified by evaluating the measured data of the membrane structure in the vacuum chamber.

Vibration Test for Membrane Structures Using Non-Contact Laser Excitation System in Vacuum Environment

Kajiwara

Obara²

2011

Vibration Measurement for Rotating Disk Using Contactless Laser Excitation

Miyamoto

Kajiwara²,

Hosoya³

2011

This paper proposes a contactless vibration testing system for rotating disks based on an impulse response excited by a laser ablation. High power YAG pulse laser is used in this system for producing an ideal impulse force on structural surface without contact. The contactless vibration testing system is composed of a YAG laser, laser Doppler vibrometer and spectrum analyzer. This system makes it possible to measure vibration characteristics of structures under operation, such as vibration measurement of a rotating disk. The effectiveness of this system is confirmed by experimental and theoretical analyses. In this paper, a platter of hard disk drive is employed as an experimental object. Vibration characteristics of a rotating and non-rotating platter are measured and compared with the results of theoretical analysis.

Vibration Control Evaluation of Micro Smart Structures with Non-Contact Laser Excitation

Nakamura

Zhu

Kajiwara³

et al. 2011

Self Cite

Smart structures technology that uses piezoelectric element etc. is effective for the vibration control of small devices. However, for micro devices, it is difficult to experimentally measure and evaluate the vibration control characteristics of the system due to its microscopic scale. Namely, it is not realistic to install an external exciter or to apply the excitation force with an impulse hammer. Therefore, in this study, the vibration property is measured and evaluated by using the non-contact excitation/measurement technology using laser ablation for the excitation and laser Doppler vibrometer for the measurement. Since both input excitation and output measurement are made without contact of apparatus and the excitation force has a high reproducibility in the present system, the efficiency and the reliability of the measurement can be improved.