Dynamic Analysis and Design of Steel-Ball Grinding Machines Based on No-Slip Cases
Based on no-slip cases between steel balls and lapping discs while a horizontal grinding machine is working, the motion equations of the ball lapping are established and the law of motion is revealed by the MATLAB software. This paper shows that the difference of the trace spacing is reduced by increasing the disc diameter, which can make the trace distribution of the steel ball surface more uniform. In order that balls do not slip when rotary disc drives them to rotate, the ranges of the lapping pressure and lapping disc speed is deduced by using the dynamics analysis considering from the vertical trench surface and along the groove surface, respectively. Finally, this paper takes the selected material as an example to analyze the process parameters that affect the lapping curves, and explains the selection principles of alpha and beta when the trench has some bias, which can provide a reference to improve the quality of the steel balls surface.
Sound and Vibration in Rolling Bearings
Progress in information technology devices and the proliferation of these devices throughout the world have occurred at an astonishingly rapid pace. Not only have there been remarkable improvements in computers, automobiles and electric home appliances, but the total number of such products owned and used by people has increased dramatically. In the midst of such advancement, demand has grown for rolling bearings with lower vibration and noise. In response, extensive research and development has been undertaken at NSK. This report summarizes some of the key findings accumulated from research on sound and vibration in bearings, and discusses vibration modes of bearing rings. In addition, a useful table summarizing sound and vibration in bearings is included as a convenient reference tool for the reader.
Evaluation of buckling load and dynamic performance of steel shear wall retrofitted with strips made of shape memory alloy
One of the most imperfections of the steel shear wall is out of plane displacements that cause severe damage in both structural and non-structural elements. In this paper, the effects of shape-memory alloys on steel shear walls are investigated. First, a numerical analysis using the finite element method in ABAQUS software has been carried out according to an experimental test. The results of the numerical analysis have been verified with experimental results. Next, shape-memory alloy fibers have been added vertically and horizontally to various parts of the steel shear wall. The results show that retrofitting with the shape-memory alloy reduces the out-of-plane displacement of the steel shear wall under both cyclic and seismic loadings. Besides, the buckling load in the steel shear wall increases when it is retrofitted with the shape-memory alloy. Also, the total out-of-plane movement (accumulated absolute displacements) of the steel shear wall and non-structural damage are controlled by the characteristic of a shape-memory alloy material called “super-elastic”.