Test Analysis Of The Acoustic Emission Signal Characteristics Of Tower Crane Material Conventional Defects

With the tower cranes of construction widely used, it causes a lot of property damage and personal injury due to lifting operations internal and abroad every year. The online positioning and testing of the source of danger is the key of the tower crane safety assessment and accident prevention. Under alternating load for a long time, metal components will produce fatigue crack in the stress concentration zone, the component variable cross-section area and weld and base metal fusion line, which will become a hidden induce major security incidents. Therefore, non-destructive testing for the above-mentioned defects has important theoretical significance and value of projects.Compared with non-destructive testing of the magnetic particle, ultrasonic, ray, acoustic emission has the advantages of high efficiency, short spection cycle, and sensitive to active defects. And it has been mature applicated in the detection of pressure vessels, aerospace and other industries. To get the acoustic emission signals of the tower crane work field is extremely complex and parameters characteristics of the material acoustic emission source lack of a typical sample, as a resoult, non-destructive testing of tower cranes based on acoustic emission technique is still at the exploratory stage. In this article, the pattern recognition and signal parameters feature extraction of acoustic emission source is toward experimental specimens prepared for conventional defects of the tower crane steel by using SDAES digital sound emission detector. The specific studies are as follows:(1) Determine the common defects in the form of the tower crane steel structure according to data analysis, and prepare the parent material specimen, surface cracks specimen and welding defects specimen.(2) Formulate a suitable experiment program and analytical methods base on acoustic emission principle and the use of the acoustic emission instrument. Measure the propagation velocity of acoustic emission signals in the Q235material by experimental methods. (3) Load test and collect acoustic emission signals of the base metal specimen, surface cracks and welding defects specimen under different loads, and real-time monitor the generated and changes of acoustic emission sources.(4) Analize the locate features, signal parameters characteristic and the spectral characteristics of acoustic emission signal through Acoustic Emission Signal Analysis Software. And finally summed up the the distribution range of main characteristic parameters typical acoustic emission signals of defective specimen.