Wavelet Technique for Damage Detection of Space Membrane Structures

Abstract

The health monitoring technique to detect the damages on the large space membrane is proposed based on wavelet transform technique and photometric stereo method. The natural vibration mode shape of membrane structures is are numerically applied to examine the effects of damage detection of the membrane using wavelet transform analysis. The results indicate that the proposed damage detection techniques can successfully detect the location and the magnitude of damages on the membrane under the tensile forces. The change in the normal vector of mode shape is proposed for damage detection using photometric stereo method. The results of the damage detection technique indicate that the precision of the normal vector is significant to detect the damage. HE damage detection techniques is significant for maintaining and controlling the navigation system of the satellites and space structural systems. The very large space structures as solar power satellites have high possibility to get the damages due to space debris because of the huge structural size and the continuum structural membrane. To detect the structural damages many research works have been investigated based on the changing the structural vibration properties in natural frequencies and vibration mode shapes. Also, by embedding optical fiber and piezoelectric devices into the structural elements, the smart structure systems are proposed to detect the damages. However, the large space structures like solar power satellites and solar sail systems, the change in the vibration properties of the structures due to the damages is quite subtle, and the embedded devices increase the structural mass and the performance in acceleration is decreased sensitively because of the very light weight spacecraft systems. In this paper, the wavelet transformation technique with photometric stereo method are proposed for detecting damages of membrane structures using the normal vector of the natural vibration mode shape. The formulations of the damage detection analyses are derived by wavelet transformation analysis. Numerical demonstrations are performed to examine the performances to detect the damages in the membrane under tensile forces using the formula. Finally, the effects of magnitude of damages length in the membrane on the reliability of damage detection performances are discussed.