Ultrasonic reflection provides a real-time way to monitor oil film thickness in a running machine with a nondestructive advantage.However,the influence mechanism of temperature on reference signals has not been clarif...Ultrasonic reflection provides a real-time way to monitor oil film thickness in a running machine with a nondestructive advantage.However,the influence mechanism of temperature on reference signals has not been clarified thus far,which hinders the precise measurement of oil film thickness.Focusing on a common three-layer structure of sensor-adhesive-steel,a global propagation model is constructed to investigate variations in the reference signal with temperature.Through finite element simulations,distinct influence mechanisms are revealed for different components.For piezoelectric sensors and the adhesive layer,temperature may induce amplitude attenuation and wave extensions in the reference signal.In the steel component,only an overall time shift is observed in the reference signal.Subsequently,a compensation model is established and validated through temperature-controlled experiments.Within the effective bandwidth,the compensation model achieves a relative error of±2%and an absolute error of±0.02 radians for the amplitude and phase of the reference waves.展开更多
Roller bearings support heavy loads by riding on an ultra-thin oil film(between the roller and raceway),the thickness of which is critical as it reflects the lubrication performance.Ultrasonic interfacial reflection,w...Roller bearings support heavy loads by riding on an ultra-thin oil film(between the roller and raceway),the thickness of which is critical as it reflects the lubrication performance.Ultrasonic interfacial reflection,which facilitates the non-destructive measurement of oil-film thickness,has been widely studied.However,insufficient spatial resolution around the rolling line contact zone remains a barrier despite the use of miniature piezoelectric transducers.In this study,a finite-element-aided method is utilized to simulate wave propagation through a three-layered structure of roller-oil-raceway under elastohydrodynamic lubrication(EHL)with nonlinear characteristics of the i)deformed curvature of the cylindrical roller and ii)nonuniform distribution of the fluid bulk modulus along the circumference of the oil layer being considered.A load and speed-dependent look-up table is then developed to establish an accurate relationship between the overall reflection coefficient(directly measured by an embedded ultrasonic transducer)and objective variable of the central oil-film thickness.The proposed finite-element-aided method is verified experimentally in a rollerraceway test rig with the ultrasonically measured oil-flm thickness corresponding to the values calculated using the EHLtheory.展开更多
基金support from the National Natural Science Foundation of China(Nos.52405597,52275126,and 52105159)the Natural Science Basis Research Plan in Shaanxi Province of China(No.2024JCYBQN-0577).
文摘Ultrasonic reflection provides a real-time way to monitor oil film thickness in a running machine with a nondestructive advantage.However,the influence mechanism of temperature on reference signals has not been clarified thus far,which hinders the precise measurement of oil film thickness.Focusing on a common three-layer structure of sensor-adhesive-steel,a global propagation model is constructed to investigate variations in the reference signal with temperature.Through finite element simulations,distinct influence mechanisms are revealed for different components.For piezoelectric sensors and the adhesive layer,temperature may induce amplitude attenuation and wave extensions in the reference signal.In the steel component,only an overall time shift is observed in the reference signal.Subsequently,a compensation model is established and validated through temperature-controlled experiments.Within the effective bandwidth,the compensation model achieves a relative error of±2%and an absolute error of±0.02 radians for the amplitude and phase of the reference waves.
文摘Roller bearings support heavy loads by riding on an ultra-thin oil film(between the roller and raceway),the thickness of which is critical as it reflects the lubrication performance.Ultrasonic interfacial reflection,which facilitates the non-destructive measurement of oil-film thickness,has been widely studied.However,insufficient spatial resolution around the rolling line contact zone remains a barrier despite the use of miniature piezoelectric transducers.In this study,a finite-element-aided method is utilized to simulate wave propagation through a three-layered structure of roller-oil-raceway under elastohydrodynamic lubrication(EHL)with nonlinear characteristics of the i)deformed curvature of the cylindrical roller and ii)nonuniform distribution of the fluid bulk modulus along the circumference of the oil layer being considered.A load and speed-dependent look-up table is then developed to establish an accurate relationship between the overall reflection coefficient(directly measured by an embedded ultrasonic transducer)and objective variable of the central oil-film thickness.The proposed finite-element-aided method is verified experimentally in a rollerraceway test rig with the ultrasonically measured oil-flm thickness corresponding to the values calculated using the EHLtheory.
