Research On Optical Fiber Information Collection Of Acoustic Emission From Local Damage Of Large Hoisting Machinery

Large hoisting machinery is one of the most widely used special equipment,which plays an important role in social production.With the rapid development of China's economy,the construction of infrastructure has been continuously strengthened,and the demand for large hoisting machinery has become more and more important.Because the local position of the large hoisting machinery is subjected to the alternating action of the load for a long time,and the working environment of the field is relatively poor,so it is easy to cause some damage.If there is no damage monitoring,it may cause some serious security incidents.Due to the sensitivity of the acoustic emission to the structural changes of metal materials and the generation and propagation of the early cracks,the acoustic emission technique is very suitable for monitoring the local damage of large lifting machinery.At present,the application of acoustic emission technology in the monitoring of the local damage of the large lifting machinery is not very mature,and the characteristics of the acoustic emission signal source and recognition is not clear enough.Based on the above reasons,the research work of this project is carried out.In this paper,the specific research work mainly includes the following aspects:In view of the present non-doing,the using of acoustic emission technology for large-scale lifting mechanical local damage uses optical fiber transmission of real-time detection.The implementation of the program is determined by the research on the acoustic emission detection system.Signal transmission contrast experiment was designed.First set of experiments:Short distance transmission and long distance transmission of cables are compared.It is found that the signal attenuation of the cable is more and more serious with the increasing of the distance of the cable.Second set of experiments:By comparing the short distance transmission and long distance transmission of the optical fiber,it is found that the acoustic emission signal transmitted over long distance optical fiber is very good to the acoustic emission signal.(The same set of experiments was carried out under the same conditions).This shows that it is feasible to use optical fiber to replace the cable for long distance transmission.Design of steel tensile test,the damage of lifting mechanical structure is simulated by experiment.Through the tensile test of Q235 steel,which is commonly used in large hoisting machinery,the experiment of acoustic emission is carried.In the process of drawing,the steel has experienced the stage of linear elastic degeneration,the plastic yield stage,the strengthening stage,the compression stage and the fracture.Through the research on the sensitivity of the signal characteristic parameter change of each stage,the frequency domain signal diagram is analyzed,and the noise signal and the acoustic emission signal are separated.Set up the experimental device in the field of production,the gantry crane running condition,beam stress concentration zone detection,acquisition of AE signal,and the signal real-time analysis,accurate judgment mechanism of crane damage.Through the study of optical information collection on sound,deepen the understanding of the large crane AE source to provide experimental basis for large local damage and heavy machinery remote monitoring,a positive role for the application of acoustic emission in related fields,safe operation of the crane to play a protective role.