The Acoustic Emission Technique Applied Research, The Helicopter Component Fatigue Crack Detection

Using acoustic emission in fatigue test and intensity research of helicopter part, the fatigue crack initiation, location and crack growth can be found. It is an effective method to discover the position and degree of damage in the materials. It is important to evaluate accurately the longevity of the part by advance the efficiency of using AE method on detecting crack in fatigue test. For successfully applying AE on detecting crack during fatigue test, noise restraining, signal locating and the building of AE features database has been deeply investigated in this thesis. In brief, the following are the primary contents: By analyzing the source of noise, several methods of restraining the noise are proposed: Space filter, Amplitude filter, BP filter, Parameters filter, Hit time setting and illustrate analysis. According to the AE characteristic of sample with different materials and shapes, the location mode of AE transducers to increase the precision in location are described in detail. And aiming at the errors in time difference measuring, wave velocity measuring and the location mode, the resolvent is proposed. To testify AE's prediction function, we use the acoustic emission in a great deal of fatigue experiments, and have attained experiential data which can be included in the AE features database. The building of AE features database is investigated. According to the demands, the structure of the database has been designed: defining data, defining table, building relation data model and designing the data structure.