Research On Wheel Ultrasonic Testing Technology Based On Dry Coupling

Large equipment in service for a long time is affected by internal pressure,corrosive medium and other factors.The inner wall of equipment is easy to produce a variety of corrosion defects,leading to medium leakage,equipment explosion and other major accidents.These conditions seriously affect the safe use of equipment,therefore equipment must be regularly defect detection.At present,the main detection method is to carry out the defect detection of the wall surface manually at high altitude,which is with the nondestructive testing equipment on the premise that the equipment is shutdown.The artificial high-altitude detection is timeconsuming and dangerous,and the shutdown also brings great economic losses to the enterprise.The realization of fully automatic online detection of equipment defects can solve the problems caused by manual detection.In this paper,the wheeled ultrasonic detection method,the solid coupling materials with good acoustic permeability and the ultrasonic dry coupling interface propagation theory are taken as the research objects.and the ultrasonic dry-coupled detection technology suitable for the automatic defect detection of large-scale equipment mounted on the wall-climbing robot is studied.The specific research content is as follows:1.A wheeled ultrasonic dry coupling detection method is proposed to detect the internal corrosion defects of equipment,which is based on the p-wave pulse reflection method to measure the defect depth.This method can realize automatic detection,replace manual operation to solve all kinds of dangerous situations and economic efficiency problems.The detection accuracy and stability are greatly improved.2.The working principle and ultrasonic propagation path of the wheeled probe are analyzed.The key technologies for the study of wheeled ultrasonic detection based on drycoupled are proposed.According to the actual working conditions,the ultrasonic pressure distribution characteristics are analyzed.According to the theoretical formula and the simulation results of ultrasonic field characteristics,and the parameters of the probe are established.Based on the theoretical analysis of the positions of the reflected signals from all kinds of surfaces,the thickness parameters of each layer of the wheeled probe are calculated to avoid the adverse effect of the superposition of signals,which make it difficult to identify the defect signals,so as to guide the structural design of the wheeled probe.3.Through the study of vertical incidence in the medium of ultrasonic propagation theory,the attenuation coefficient and the impedance matching theory are derived.Analyzed the influence of the solid coupling material ultrasonic through performance parameters.Choose different types of solid coupling material.At the same time,a new type of solid coupling material was prepared,and the time domain and frequency domain analysis of the experiment and data were carried out to obtain the best coupling material.4.The sound propagation characteristics of a wheeled ultrasonic probe under non-ideal contact at the dry-coupled detection interface are studied.On the basis of the classical theory,the relationship between the interface reflection coefficient,the surface roughness and the new interface pressure coupling interface model is deduced.Compared with other models,it has better fit.The simulation analysis of the model by MATLAB shows that the roughness of drycoupled interface can significantly reduce the coupling effect.Increasing the pressure between solid interfaces can improve the coupling performance.By establishing the stochastic rough interface model,the influence of detection interface and interface pressure can be quantitatively analyzed to guide the use of wheeled probe.5.According to the design of the structural parameters of the wheeled probe,the solid coupling material is poured into the mold,and the wheeled dry-coupled probe is produced.The performance experimental research,the application research of the probe is conducted,the performance experiments are conducted to verify whether the performance of the probe could meet the actual needs.It is proved that the dry coupling model can be used to detect wheeled probe and the application of the probe is studied.Wheel-type dry-coupled probe is installed on the wall-climbing robot,and the collected defect echo signal can be used for data analysis of the detection robot.At last,the experiment of the robot is carried out to simulate the actual working condition,and a good test result is obtained.