| Aeronautical engineering structures are likely to suffer from damage under fatigue loading andthere may be crack initiation at structural hot spots during service. With the development of smartmaterials and structures, it is now possible that advanced actuation/sensing elements integrated into orsurface bonded on structures are used to acquire the structural health status related information in situand in time and then to identify the structural safety status. Applying the structural health monitoringsystem to obtain the information about the damage characteristic and severity is of great significanceto prevent the disastrous consequence caused by structural property deterioration and failure, improveand increase the security of structures and reduce the maintenance cost of aeronautical structures.This thesis focuses on researches about identification and monitoring of crack emerged ataeronautical structure hot spot and damage induced by low speed impact in advanced compositelaminate. First aiming at the lug joint structure, the statistical pattern identification method is used toconvert the structural health monitoring to pattern identification. The time and frequency domaincharacteristic acquired from the response signal is input to the Bayesian classifier, and then aftertraining and testing of the classifier, the length of the fatigue crack at the lug joint is identified.Second, aiming at the composite laminate, a damage index based weighted average merginglocalization algorithm is proposed to identify delamination by impact. The proposed algorithm isvalidated by artificial damage in experiments. At last, a full functioned dual module structural healthmonitoring system that is based on virtual instrument technology and algorithm development is usedfor some critical part of aeronautical structures such as the lug joint and the composite laminate. Theeffectiveness and reliability of the structural health monitoring is validated by experiments. |
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