Based on Hertz contact theory, contact area parameters between ball and raceway are calculated. Using the Creep theory of Cater and V-J theory, adhesive area and micro-slip area in the contact area are analyzed. It is...Based on Hertz contact theory, contact area parameters between ball and raceway are calculated. Using the Creep theory of Cater and V-J theory, adhesive area and micro-slip area in the contact area are analyzed. It is considered that micro-adhesion wear of micro convex body in the slip area is the main reason for accuracy degradation of a linear ball guide pair. And, the characteristics of the contact area between ball and raceway of slider are characterized using the fractal function. Fractal parameters are obtained using the least squares fitting double logarithmic graph structure function. Considering the lubrication condition between the ball and rail of slider, stress analysis is carried out on the adhesive area. A fractal-creep model of contact surfaces is established in the micro-slip region. The fractal parameters of a certain guide rail are measured, and the wear degradation process of linear rolling guide is simulated. Finally, the relationship between wear and relative tangential velocity, normal load and running mileage of linear ball guide is obtained.展开更多
The traditional one-dimensional ultrasonic beam steering has time delay and is thus a complicated problem. A numerical model of ultrasonic beam steering using Neumann boundary condition in multiplysics is presented in...The traditional one-dimensional ultrasonic beam steering has time delay and is thus a complicated problem. A numerical model of ultrasonic beam steering using Neumann boundary condition in multiplysics is presented in the present paper. This model is based on the discrete wave number method that has been proved theoretically to satisfy the continuous conditions. The propagating angle of novel model is a function of the distance instead of the time domain. The propagating wave fronts at desired angles are simulated with the single line sources for plane wave. The result indicates that any beam angle can be steered by discrete line elements resources without any time delay.展开更多
基金Supported by the National Natural Science Foundation of China(No.51505012,51575014)the Natural Science Foundation of Beijing(No.3154029,KZ201410005010)+1 种基金the Important National Science&Technology Specific Projects of China(No.2012ZX04010021-001-004)Beijing Postdoctoral Research Foundation(No.2015XX-13)
文摘Based on Hertz contact theory, contact area parameters between ball and raceway are calculated. Using the Creep theory of Cater and V-J theory, adhesive area and micro-slip area in the contact area are analyzed. It is considered that micro-adhesion wear of micro convex body in the slip area is the main reason for accuracy degradation of a linear ball guide pair. And, the characteristics of the contact area between ball and raceway of slider are characterized using the fractal function. Fractal parameters are obtained using the least squares fitting double logarithmic graph structure function. Considering the lubrication condition between the ball and rail of slider, stress analysis is carried out on the adhesive area. A fractal-creep model of contact surfaces is established in the micro-slip region. The fractal parameters of a certain guide rail are measured, and the wear degradation process of linear rolling guide is simulated. Finally, the relationship between wear and relative tangential velocity, normal load and running mileage of linear ball guide is obtained.
基金supported by the National Natural Science Foundation of China (10972014)
文摘The traditional one-dimensional ultrasonic beam steering has time delay and is thus a complicated problem. A numerical model of ultrasonic beam steering using Neumann boundary condition in multiplysics is presented in the present paper. This model is based on the discrete wave number method that has been proved theoretically to satisfy the continuous conditions. The propagating angle of novel model is a function of the distance instead of the time domain. The propagating wave fronts at desired angles are simulated with the single line sources for plane wave. The result indicates that any beam angle can be steered by discrete line elements resources without any time delay.
