Calibration and analysis of ultrasonic stress coefficient based on finite element simulation
As the key link of ultrasonic stress detection,stress coefficient calibration directly determines the accuracy of stress detection results.The traditional calibration of stress coefficient is sensitive to such factors as surface roughness,coupling thickness and contact force between acoustic matching block and measured object.Coupled with the influence factors,it is more difficult to accurately calibrate the stress coefficient.This paper puts forward that the stress coefficient can be divided into two parts:the basic value reflecting the acoustic elastic effect of materials and the value considering the influence of various detection factors.A multi-physical coupling ultrasonic stress detection model was established based on finite element software.Different tensile loads were applied to calculate and analyze the relationship between the arrival time of critical refraction longitudinal wave and different stress values.The results show that the basic value of ultrasonic stress coefficient of the simulated calibration 45# steel is 13.7 MPa/ns.Through four groups of uniaxial horizontal tensile tests,the influence values of test factors were calibrated as 1.0 MPa/ns,1.7 MPa/ns,2.8 MPa/ns and 6.8 MPa/ns,respectively.Under reasonable circumstances,the basic value of stress coefficient directly determines the value of stress coefficient,and the influence of test factors on the value of force system should be small.The factor influence value of 6.8 MPa/ns is 49.6％of the basic value of 13.7 MPa/ns,which is beyond the reasonable range.After observation,it is found that there are small gaps in the sound matching block after coupling with the measured surface,which can be judged as invalid data.The finite element model simulated the basic value of stress coefficient under the ideal detection conditions.By comparing the basic value of stress coefficient and the influence value of detection factors,the quality of detection can be judged,the discreteness of stress coefficient calibration data can be reduced,and the reliability of ultrasonic stress detection results can be improved.
Coefficient of stressUltrasonic simulationCritical refraction longitudinal waveAcoustic elastic effect
万方数据
维普
