Theoretical And Experimental Research On Structural Health Monitoring For Space Structure

Large space structure are the symbol of the national building science and technology for not only its novel and prolific style but also plenty of new material and new technology have been adopted. Space structures are inevitable to suffer from environmental corrosion, long term fatigue effects or natural disasters, and then the damage accumulates during long service period. Therefore, intelligent heath monitoring and damage diagnosis for structures become an important technology to study.Detailed research are carried out for space structure heath monitoring by combining the status quo of structural health monitoring and structural condition assessment. The related important problems about structural health monitoring, such as model update, optimal placement of sensors, damage detection and information fusion, are lucubrated and a series of new methods are proposed. The main contents of this dissertation are described as follows:1. Sensitivity analysis is carried out for structural dynamic equation by wavelet, and the accelerate signal sensitivity is solved. Damage time for a structure can be detected by Lipschitz index, which is gained by module maximum of wavelet transform and is viewed as an index for identifying mutational degree of signals. Damage degree for a structure can be detected by energy spectrum at different frequency bands for the signal decomposed by wavelet packets.2. Model update for space structure is studied. Because too much samples for training Artificial Neuron Network are demanded, uniform design method is used to produce samples in order to reduce the amount of samples in the process of structural damage simulation. Genetic Algorithm is used to optimize the initial weight of back propagation network and the operation efficiency is enhanced. A recurrence update method based on substructures and ANN is presented especially for spatial structures. A structure is divided into multilayer substructures, the updating is realized step by step and a proper damage factor is...