A new nonlinear force model based on experimental data is proposed to replace the classical Hertzian contact model to solve the fractional index nonlinearity in a ball bearing system. Firstly, the radial force and the...A new nonlinear force model based on experimental data is proposed to replace the classical Hertzian contact model to solve the fractional index nonlinearity in a ball bearing system. Firstly, the radial force and the radial deformation are measured by statics experiments, and the data are fitted respectively by using the Hertzian contact model and the cubic polynomial model. Then~ the two models are compared with the approximation formula appearing in Aeroengine Design Manual. In consequence, the two models are equivalent in an allowable deformation range. After that, the relationship of contact force and contact deformation for single rolling element between the races is cal- culated based on statics equilibrium to obtain the two kinds of nonlinear dynamic models in a rigid-rotor ball bearing system. Finally~ the displacement response and frequency spectrum for the two system models are compared quantitatively at different rotational speeds, and then the structures of frequency-amplitude curves over a wide speed range are compared qualitatively under different levels of radial clearance, amplitude of excitation, and mass of supporting rotor. The results demonstrate that the cubic polynomial model can take place of the Hertzian contact model in a range of deformation.展开更多
Theoretical studies show that a Hertzian-conical crack can be considered to be composed of double cone faces for simplicity. In the present study, the three-dimensional finite-difference time-domain method is employed...Theoretical studies show that a Hertzian-conical crack can be considered to be composed of double cone faces for simplicity. In the present study, the three-dimensional finite-difference time-domain method is employed to quantify the electric-field distribution within the subsurface in the presence of such a defect under normal incidence irradiation. Both impurities （inside the crack） and the chemical etching have been investigated. The results show that the maximum electric field amplitude │E│max is 9.57374 V/m when the relative dielectric constant of transparent impurity equals 8.5. And the near-field modulation will be improved if the crack is filled with the remainder polishing powders or water vapor/drops. Meanwhile, the laser-induced initial damage moves to the glass-air surface. In the etched section, the magnitude of intensification is strongly dependent on the inclination angle θ. There will be a highest modulation when θ is around π/6, and the maximum value of IEImax is 18.57314 V/m. When θ ranges from π/θ to π/4, the light intensity enhancement factor can easily be larger than 100, and the modulation follows a decreasing trend. On the other hand, the modulation curves become smooth when θ〉π/4 or θ 〈 π/8.展开更多
In this paper the Auerbach＇s scaling law of Hertzian fracture induced by a spherical indenter pressing on a brittle solid is studied. In the analysis, the singular integral equation method is used to analyze the frac...In this paper the Auerbach＇s scaling law of Hertzian fracture induced by a spherical indenter pressing on a brittle solid is studied. In the analysis, the singular integral equation method is used to analyze the fracture behavior of the Hertzian contact problem. The results show that the Auerbach＇s constant sensitively depends on the Poisson＇s ratio, and the effective Auerbach＇s domain is also determined for a given value of the Poisson＇s ratio.展开更多
Aero engine seal coatings can effectively improve the air tightness of aircraft engines and increase fuel efficiency.However,due to the frictional forces between the blades and the coating,the coating often flakes off...Aero engine seal coatings can effectively improve the air tightness of aircraft engines and increase fuel efficiency.However,due to the frictional forces between the blades and the coating,the coating often flakes off,resulting in damage to the blades and causing eco-nomic losses.Therefore,it is necessary to analyze the friction between the blades and the coating.In this paper,three ceramic-based high-temperature seal coatings with different polyphenylene ester contents and a pure Yttria-stabilised zirconia coating were prepared by atmo-spheric plasma spraying(APS).The hardness and modulus of elasticity of the coated surfaces were obtained by hardness and modulus of elasticity tests,and the coatings were subjected to high-speed touch abrasion tests.The Hertzian contact model was used to calculate the maximum normal contact load on the coating during the process.The test values were compared with the theoretical values and it was found that the calculated values were always greater than the test values.In order to make the Hertzian contact model more accurate in calculating the touching and abrasion forces,the contact coefficients in the Hertzian contact model were optimized.Substituting the optimized coeffi-cients into the Hertzian contact model,the results show that the calculated results after optimizing the coefficients are much closer to the test values,with deviations from the test values ranging from 1%to 38%.展开更多
Physics-informed neural network(PINN)provides a novel method for understanding the mechanical behavior of tribology contacts,and the deformation of the contacting body plays a pivotal role in determining the contact s...Physics-informed neural network(PINN)provides a novel method for understanding the mechanical behavior of tribology contacts,and the deformation of the contacting body plays a pivotal role in determining the contact scenario of dry and elastohydrodynamic lubricated(EHL)contacts.Here,we delineate the design and construction of the PINN for obtaining elastic deformations under Hertzian pressure.The PINN obtains the elastic deformation by transforming the linear elasticity equation into an optimized neural network,which presents a new method for obtaining elastic deformation in tribological contacts.Our results are consistent with the results from finite element method.Hence,we envision that our method has great application potential in dry and EHL contacts in the prediction of elastic deformation.展开更多
The contact characteristics between cycloidal gear teeth and pinwheel teeth significantly impact the operational performance of cycloidal pinwheel mechanisms.Current research methods tend to rely primarily on theoreti...The contact characteristics between cycloidal gear teeth and pinwheel teeth significantly impact the operational performance of cycloidal pinwheel mechanisms.Current research methods tend to rely primarily on theoretical calculations,with limited use of experimental methods for detecting dynamic contact properties.We propose a novel method for testing the dynamic contact characteristics of cycloidal pinwheel mechanisms.By combining Hertzian contact theory and contact strength theory,we establish a force and meshing stiffness model for the cycloidal and pinwheel gears,and determine the maximum contact stress and variations in pinwheel gear force and meshing stiffness.Based on the principle of photoelasticity,we built a testing platform for the cycloidal pinwheel mechanism to assess its contact characteristics.This platform provides the stress distribution of the cycloidal pinwheel mechanism and allows us to deduce key parameters such as the number of meshing teeth and the meshing interval.This study provides an experimental method for investigating the contact characteristics of cycloidal pinwheel mechanisms.展开更多
轨道车辆非线性临界速度计算结果完全取决于求解轮轨接触问题的准确性,而轮轨接触力又对车辆-轨道系统运动有复杂且高度非线性的依赖性,如轮轨接触斑的形状、接触位置的局部弹性行为和摩擦效应。因此,轮轨蠕滑力建模对于评估车辆非线性...轨道车辆非线性临界速度计算结果完全取决于求解轮轨接触问题的准确性,而轮轨接触力又对车辆-轨道系统运动有复杂且高度非线性的依赖性,如轮轨接触斑的形状、接触位置的局部弹性行为和摩擦效应。因此,轮轨蠕滑力建模对于评估车辆非线性稳定性至关重要。为了评估轮轨蠕滑力模型对轨道车辆非线性稳定性的影响,基于非赫兹接触理论建立了轮轨蠕滑力计算模型,利用降速法和BS EN 14363:2016标准确定了车辆非线性临界速度,并与赫兹蠕滑力模型的结果进行了对比。结果表明,轮轨蠕滑力模型对车辆的非线性稳定性评估有不同程度的影响,主要取决于轮轨接触斑的非椭圆化程度。相较于赫兹接触模型,非赫兹接触模型更适用于非线性稳定性评估,因为传统赫兹接触模型可能会在某些情况下错误估计车辆的动力学行为。展开更多
基金Project supported by the National Basic Research Program(973 Program)of China(No.2015CB057400)the National Natural Science Foundation of China(No.11602070)+1 种基金the China Postdoctoral Science Foundation(No.2016M590277)the Heilongjiang Postdoctoral Financial Assistance(No.LBH-Z16067)
文摘A new nonlinear force model based on experimental data is proposed to replace the classical Hertzian contact model to solve the fractional index nonlinearity in a ball bearing system. Firstly, the radial force and the radial deformation are measured by statics experiments, and the data are fitted respectively by using the Hertzian contact model and the cubic polynomial model. Then~ the two models are compared with the approximation formula appearing in Aeroengine Design Manual. In consequence, the two models are equivalent in an allowable deformation range. After that, the relationship of contact force and contact deformation for single rolling element between the races is cal- culated based on statics equilibrium to obtain the two kinds of nonlinear dynamic models in a rigid-rotor ball bearing system. Finally~ the displacement response and frequency spectrum for the two system models are compared quantitatively at different rotational speeds, and then the structures of frequency-amplitude curves over a wide speed range are compared qualitatively under different levels of radial clearance, amplitude of excitation, and mass of supporting rotor. The results demonstrate that the cubic polynomial model can take place of the Hertzian contact model in a range of deformation.
基金Project supported by the Young Scientists Fund of the National Natural Science Foundation of China (Grant No.10904008)the Joint Fund of the National Natural Science Foundation of China and the China Academy of Engineering Physics (GrantNo. 11076008)the Scientific Research Foundation for the Central Universities of China (Grant Nos.ZYGX2009X007,ZYGX2010J045, and ZYGX2011J043)
文摘Theoretical studies show that a Hertzian-conical crack can be considered to be composed of double cone faces for simplicity. In the present study, the three-dimensional finite-difference time-domain method is employed to quantify the electric-field distribution within the subsurface in the presence of such a defect under normal incidence irradiation. Both impurities （inside the crack） and the chemical etching have been investigated. The results show that the maximum electric field amplitude │E│max is 9.57374 V/m when the relative dielectric constant of transparent impurity equals 8.5. And the near-field modulation will be improved if the crack is filled with the remainder polishing powders or water vapor/drops. Meanwhile, the laser-induced initial damage moves to the glass-air surface. In the etched section, the magnitude of intensification is strongly dependent on the inclination angle θ. There will be a highest modulation when θ is around π/6, and the maximum value of IEImax is 18.57314 V/m. When θ ranges from π/θ to π/4, the light intensity enhancement factor can easily be larger than 100, and the modulation follows a decreasing trend. On the other hand, the modulation curves become smooth when θ〉π/4 or θ 〈 π/8.
基金supported by the National Natural Science Foundation of China(No.10772058)
文摘In this paper the Auerbach＇s scaling law of Hertzian fracture induced by a spherical indenter pressing on a brittle solid is studied. In the analysis, the singular integral equation method is used to analyze the fracture behavior of the Hertzian contact problem. The results show that the Auerbach＇s constant sensitively depends on the Poisson＇s ratio, and the effective Auerbach＇s domain is also determined for a given value of the Poisson＇s ratio.
基金supported by Basic Research Funds for Central Universities(3122019189).
文摘Aero engine seal coatings can effectively improve the air tightness of aircraft engines and increase fuel efficiency.However,due to the frictional forces between the blades and the coating,the coating often flakes off,resulting in damage to the blades and causing eco-nomic losses.Therefore,it is necessary to analyze the friction between the blades and the coating.In this paper,three ceramic-based high-temperature seal coatings with different polyphenylene ester contents and a pure Yttria-stabilised zirconia coating were prepared by atmo-spheric plasma spraying(APS).The hardness and modulus of elasticity of the coated surfaces were obtained by hardness and modulus of elasticity tests,and the coatings were subjected to high-speed touch abrasion tests.The Hertzian contact model was used to calculate the maximum normal contact load on the coating during the process.The test values were compared with the theoretical values and it was found that the calculated values were always greater than the test values.In order to make the Hertzian contact model more accurate in calculating the touching and abrasion forces,the contact coefficients in the Hertzian contact model were optimized.Substituting the optimized coeffi-cients into the Hertzian contact model,the results show that the calculated results after optimizing the coefficients are much closer to the test values,with deviations from the test values ranging from 1%to 38%.
基金supported by the Guangdong Basic and Applied Basic Research Foundation(No.2023A1515240032)the Scientific Research Startup Fund for Shenzhen High-caliber Personnel of SZPU(No.6022310045k)the Shenzhen Polytechnic University Research Fund(No.6024310009K).
文摘Physics-informed neural network(PINN)provides a novel method for understanding the mechanical behavior of tribology contacts,and the deformation of the contacting body plays a pivotal role in determining the contact scenario of dry and elastohydrodynamic lubricated(EHL)contacts.Here,we delineate the design and construction of the PINN for obtaining elastic deformations under Hertzian pressure.The PINN obtains the elastic deformation by transforming the linear elasticity equation into an optimized neural network,which presents a new method for obtaining elastic deformation in tribological contacts.Our results are consistent with the results from finite element method.Hence,we envision that our method has great application potential in dry and EHL contacts in the prediction of elastic deformation.
基金Sponsored by Natural Science Foundation of Hebei Province(Grant No.E2019209153)Tangshan Science and Technology Program(Grant No.22130219G).
文摘The contact characteristics between cycloidal gear teeth and pinwheel teeth significantly impact the operational performance of cycloidal pinwheel mechanisms.Current research methods tend to rely primarily on theoretical calculations,with limited use of experimental methods for detecting dynamic contact properties.We propose a novel method for testing the dynamic contact characteristics of cycloidal pinwheel mechanisms.By combining Hertzian contact theory and contact strength theory,we establish a force and meshing stiffness model for the cycloidal and pinwheel gears,and determine the maximum contact stress and variations in pinwheel gear force and meshing stiffness.Based on the principle of photoelasticity,we built a testing platform for the cycloidal pinwheel mechanism to assess its contact characteristics.This platform provides the stress distribution of the cycloidal pinwheel mechanism and allows us to deduce key parameters such as the number of meshing teeth and the meshing interval.This study provides an experimental method for investigating the contact characteristics of cycloidal pinwheel mechanisms.
文摘轨道车辆非线性临界速度计算结果完全取决于求解轮轨接触问题的准确性,而轮轨接触力又对车辆-轨道系统运动有复杂且高度非线性的依赖性,如轮轨接触斑的形状、接触位置的局部弹性行为和摩擦效应。因此,轮轨蠕滑力建模对于评估车辆非线性稳定性至关重要。为了评估轮轨蠕滑力模型对轨道车辆非线性稳定性的影响,基于非赫兹接触理论建立了轮轨蠕滑力计算模型,利用降速法和BS EN 14363:2016标准确定了车辆非线性临界速度,并与赫兹蠕滑力模型的结果进行了对比。结果表明,轮轨蠕滑力模型对车辆的非线性稳定性评估有不同程度的影响,主要取决于轮轨接触斑的非椭圆化程度。相较于赫兹接触模型,非赫兹接触模型更适用于非线性稳定性评估,因为传统赫兹接触模型可能会在某些情况下错误估计车辆的动力学行为。
