Damage Detection for Space Truss Structures Based on Strain Mode under Ambient Excitation

Abstract

Safety assurance and detection of potential damage for space truss structures have been challenging topics. The two most critical problems are considered in this paper. One is to develop an effective damage detection method based on strain data under ambient excitation, and the other is then to optimize the installment of strain sensors owing to numerous structural members in the space truss structures. A method of damage detection for space truss structures, called the environmental excitation incomplete strain mode (EEISM) method, is proposed. Four steps are taken in the EEISM method. First, strain mode parameter identification is carried out based on the cross-correlation function of the strain responses through a combination of the empirical mode decomposition method and the peak amplitude series method. Second, the strain sensors are located optimally in the space truss structures through sensitive analysis of the strain mode perturbation matrix, which are obtained by perturbation theory. Third, the modal assurance criterion (MAC) value is applied to locate the damages; that is, the members with the larger MAC values are defined as the damaged members. Finally, a damage index obtained by solving the perturbation equation is used for damage quantification. Numerical analysis of a long-span space truss structure including damage location and quantification for single-member and multimember damages, detection of the various severities of damage, and the effect of the number of sensors is performed to verify the effectiveness of the proposed EEISM method. It is shown from the analysis results that the EEISM method is effective in the location and quantification of damages for single-member and multimember damages. The quantity of the strain sensors has an effect on the damage location and has no remarkable effect on the damage quantification for the determined damage members.