This paper presents a new theoretical model to determine the optimal axial preload of a spindle system, for challenging the traditional method which relies heavily on experience of engineers. The axial preloading stif...This paper presents a new theoretical model to determine the optimal axial preload of a spindle system, for challenging the traditional method which relies heavily on experience of engineers. The axial preloading stiffness was treated as the sum of the spindle modal stiffness and the framework elastic stiffness, based on a novel concept that magnitude of preloads can be controlled by measuring the resonant frequency of a spindle system. By employing an example of a certain type of aircraft simulating rotary table, the modal stiffness was measured on the Agilent 35670A Dynamic Signal Analyzer by experimental modal analysis. The equivalent elastic stiffness was simulated by both finite element analysis in ANSYS? and a curve fitting in MATLAB?. Results showed that the static preloading stiffness of the spindle was 7.2125×107 N/m, and that the optimal preloading force was 120.0848 N. Practical application proved the feasibility of our method.展开更多
The distribution of shear stress on the cross-section of plastic metal solid circular shaft under pure torsion yielding, the applicability of complete plastic model assumption and the shear stress formula were researc...The distribution of shear stress on the cross-section of plastic metal solid circular shaft under pure torsion yielding, the applicability of complete plastic model assumption and the shear stress formula were researched. Based on the shear stress formula of circular shaft under pure torsion in elastic stage, the formula of torque in elastic stage and the definition of yield, it is obtained that the yielding stage of plastic metal shaft under pure torsion is only a surface phenomenon of torque-torsion angle relationship, and the distribution of shear stress is essentially different from that of tensile stress when yielding under uniaxial tension. The pure torsion platform-torsion angle and the shape of torque-torsion angle curve cannot change the distribution of shear stress on the shaft cross-section. The distribution of shear stress is still linear with the maximum shear stress ts. The complete plasticity model assumption is not in accordance with the actual situation of shaft under torsion. The experimental strength data of nine plastic metals are consistent with the calculated results of the new limiting strain energy strength theory （LSEST）. The traditional yield stress formula for plastic shaft under torsion is reasonable. The shear stress formula based on the plane assumption in material mechanics is applicable for all loaded stages of torsion shaft.展开更多
文摘This paper presents a new theoretical model to determine the optimal axial preload of a spindle system, for challenging the traditional method which relies heavily on experience of engineers. The axial preloading stiffness was treated as the sum of the spindle modal stiffness and the framework elastic stiffness, based on a novel concept that magnitude of preloads can be controlled by measuring the resonant frequency of a spindle system. By employing an example of a certain type of aircraft simulating rotary table, the modal stiffness was measured on the Agilent 35670A Dynamic Signal Analyzer by experimental modal analysis. The equivalent elastic stiffness was simulated by both finite element analysis in ANSYS? and a curve fitting in MATLAB?. Results showed that the static preloading stiffness of the spindle was 7.2125×107 N/m, and that the optimal preloading force was 120.0848 N. Practical application proved the feasibility of our method.
文摘The distribution of shear stress on the cross-section of plastic metal solid circular shaft under pure torsion yielding, the applicability of complete plastic model assumption and the shear stress formula were researched. Based on the shear stress formula of circular shaft under pure torsion in elastic stage, the formula of torque in elastic stage and the definition of yield, it is obtained that the yielding stage of plastic metal shaft under pure torsion is only a surface phenomenon of torque-torsion angle relationship, and the distribution of shear stress is essentially different from that of tensile stress when yielding under uniaxial tension. The pure torsion platform-torsion angle and the shape of torque-torsion angle curve cannot change the distribution of shear stress on the shaft cross-section. The distribution of shear stress is still linear with the maximum shear stress ts. The complete plasticity model assumption is not in accordance with the actual situation of shaft under torsion. The experimental strength data of nine plastic metals are consistent with the calculated results of the new limiting strain energy strength theory （LSEST）. The traditional yield stress formula for plastic shaft under torsion is reasonable. The shear stress formula based on the plane assumption in material mechanics is applicable for all loaded stages of torsion shaft.
