Integrated data processing method for estimatingshaft destruction kinetics

Purpose. Improving the method of monitoring the development of fatigue cracks in machine parts, in particular the gearbox shaft, based on the use of ultrasonic non-destructive testing. This allows to increase the accuracy of estimating the durability and parameters of the fracture process, reduce errors in the processing of experimental data and ensure the detection of cracks at the early stages of development. The methods. The research methods were based on the principles of the theory of fracture mechanics. The study was conducted on the example of a gearbox shaft, which was tested for fatigue by the symmetrical plane bending method at a frequency of 20 Hz. An ultrasonic flaw detector was used to monitor the development of cracks, which allows establishing the dependence between the signal from the crack, its size and the number of load cycles. Data processing was performed using the integral form of the Paris equation, which makes it possible to avoid errors in numerical differentiation and take into account the parameters of the fracture process. Findings. The proposed method allowed to detect cracks at the early stage of development 1.5–3 times faster than visual methods. A quantitative relationship between the signal amplitude and the crack size has been established, which is confirmed by experimental data. The calculated parameters of the Paris equation using the conjugate gradient method indicate a close correlation between the coefficients. The difference between the calculated and experimental estimates of durability does not exceed 40%. The originality. A new approach to the processing of experimental data has been developed, which addresses the need for numerical differentiation and interpolation of points, which, in turn, reduces losses in the analysis of deposits between periods cracks due to the number of cycles of wear. First, a vicoristic integral form of the Peris equation was used to estimate the parameters of the kinetics of gearbox shaft alignment, which makes it possible to more accurately determine the fluidity of the growth of internal cracks. A close relationship has been established between the amplitude of the ultrasonic signal and the size of the crack, which makes it possible to increase the reliability of control at the early stages of destruction. A close correlation between the coefficients of the Peris level was revealed, which is confirmed by the results obtained using the method of obtaining gradients. Practical implementation. The proposed method allows to significantly increase the accuracy of monitoring fatigue fracture of machine parts and determining their durability. Detection of cracks at early stages of development ensures timely detection of defects, which contributes to increasing the reliability and safety of equipment operation.