19b. TELEPHONE NUMBER (include arsacodeIn current technologies, given the high rehability required in almost all systems, the ability to detect a system fault at the earliest possible stage is of primary interest. The routine manual inspections required for structures in mechanical, civil and aerospace fields, significantly increase maintenance cost. Our objective is to develop and implement a selfdiagnostic tool that would reduce costs while also increasing system efiiciency and reducing risk. In addition, diagnostic tools can provide information on inaccessible parts in the structure. To provide the necessary architecture for this health maintenance, an array of sensor is used to monitor the system.
Status of EffortDuring this grant, a fault detection filter was developed for structural health monitoring of a simply supported beam. More complex structtrres would be addressed later. The filter design is based on a mathematical model of the structure and rehes on foiu: measurements and one actuation point. Based on structural analysis, the structural damage is decomposed 1 and reduced to a fault direction vector that maintains a fixed direction in the detection space. We show that this fault detection vector can be detected and uniquely identified and thereby, the structural damage is detected and localized.3 Accomplishments/New Findings During this grant, robust fault detection filter based on a spectral design method is implemented for a simply supported beam and is shown to both identify and localize structural faults. See Appendix A for details. The algorithm is specifically accomplished using 4 sensors and 1 actuator and relays on a mathematical model of the structure. The detection filter design is based on fault direction vectors that can be uniquely associated with any structural fault occurring at the beam. At each damage locations the detection filter measurement residual vector produces a fibced direction independent of the fault (damage) size that can be uniquely identified. The numerical simulations are compared with experimental results produced by an aluminum simply supported beam and show good agreement. The measvirements and actuation of the beam are obtained with piezoelectric transducers that ensure a large operating bandwidth. Although the algorithm is designed specifically for 4 measurements, it can be adapted to virtually any number of sensors. This is a fundamental properties for structural health monitoring because, depending on structure complexity, the damage detection must be accomplished using the least number of sensors. The faultdetection filter methodology can also include sensors and actuator faults, as well as plant faults as addressed here. However, in this grant period, only structural faults are considered.For the implementation of the fault detection filter, the following equipments where utilized: 1) A Wavetek lOMHz DDs Mod. 29 function generator to produce the sinusoidal inputs for the actuator, 2) a low impedance Burleigh PZ 150M volt amplifier for the ampUfication of the ...