Research On Contact Stress Of Iron-Chromium Alloy Based On Ultrasonic Guided Wave Technology

There are a large number of metal columnar parts in contact with each other in the industrial field.In order to reduce the damage of the equipment during the production process and ensure the safe and stable operation of the metal parts,the detection of the key mechanical indicators of the contact area is of great significance to its safe production.Current detection of contact stress includes X-ray diffraction method,stress measurement based on magnetoelastic effect,ultrasonic echo method,etc.X-ray diffraction method has disadvantages such as small penetration depth and too long single-point test time;stress measurement method based on magnetoelastic effect The resulting hysteresis phenomenon will cause the magnetic force to stay permanently in the sensitive parts,which will directly adversely affect the ferromagnetic parts.The ultrasonic echo method utilizes the propagation characteristics of ultrasonic waves in ferromagnetic components,and uses ultrasonic echo carrying characteristic information for the characterization of contact stress.It has the advantages of high accuracy,long detection distance,and no damage to the metal parts to be measured.The paper uses ultrasonic guided wave characterization technology to realize the measurement of contact stress and loading force of metal parts in contact with each other.The paper analyzes the contact process of the waveguide rod and the propagation characteristics of ultrasonic guided waves;simulation verification is carried out with the help of finite element software,and the comparison error between the contact stress simulation results and the analytical value is within 3%,and the comparison error between the ultrasonic guided wave simulation model and the measured value Both are within 1%.From the perspective of numerical simulation,the feasibility of using ultrasonic echo information to characterize the mechanical characteristics of the waveguide rod contact area is verified;a signal excitation source emission/recovery circuit,an ultrasonic echo signal acquisition circuit,and a voltage control gain are developed.The experimental system platform for adjusting circuit,digital-analog and analog-to-digital conversion circuit.The paper sets up four sets of angle models(90°,60°,45°,30°)between the waveguide rod and the axis of the cylindrical component,and uses the developed system platform to conduct experiments.By collecting ultrasonic echo signals and processing the transit time algorithm,Obtain the ultrasonic guided wave transmission time difference increment in the reference pitch of the front end of the waveguide rod,and complete the calibration of the loading force and contact stress according to the ultrasonic guided wave transmission time difference increment.Experiments show that in the range of 40N-100 N,the transmission time difference increase and the load force change curve have a good degree of discrimination at different angles,and the measured value is consistent with the function analytical value;the experiment shows that the contact area can be characterized by the transmission time difference increase Loading force and contact stress.The research in the thesis shows that the loading force and the axis angle are the two main factors that change the mechanical index of the contact area,and both affect the ultrasonic parameters and the contact stress value.Therefore,the mechanical properties of the contact area can be characterized by the ultrasonic parameters.