Papers by Author: Bo Li

Abstract: Automatic open-parachute-device is an essential device in the field of aviation life-saving technology. In this paper, on the basic of the open-parachute-device mechanism, structure of its reliability function is given. According to its reliability indicators, considering the main failure mode and combining with similar products' reliability statistical data, analysis and design of reliability indicators are processed. Successively according to the principle of "redistribution method" and the principle of "proportional distribution method" about failure rate, the reliability indicators are calculated in detail. The results showed that the reliability indicators allocation with the "proportional distribution method" is little different from the reliability indicators allocation with the "redistribution method", but the former is more in line with the requirements. This design has a guiding significance to the product production.

Abstract: Influence of the damping ratio on the response fast performance to under-damped second-order system in the time domain has been discussed. The relationship between peak time and the input signal, the adjust time, and the system type has been analyzed. The response’s fast performance indicators are relative, and it is related to the input signal, the response of the system, and the type of system and its initial states. In conclusion, the peak time and the adjust time cannot reach a minimum at the same time. The fast response issue must be discussed in relation to specific cases, and it cannot be generalized.

Abstract: Transfer function (TF) for linear time invariant system and optical transfer function (OTF) for linear space shaft invariant system are compared and contrasted. TF is the unilateral Laplace transform of system’s one-dimensional unit impulse response, dimensions of the input and output may be same or different, TF can be used to describe a variety of filter or to express solution of linear differential equations accurately. But OTF is the Fourier transform of system’s two-dimensional impulse response, dimensions of the input and output must be same, OTF can be used only to describe a low-pass filter or to express solution of the linear univariate partial differential equations approximately. Their eigenfunctions are similar complex exponential functions. OTF has stricter requirements and application conditions than TF. It is helpful to the readers’ understanding of TF and OTF.

Abstract: Vibration-assisted machining (VAM) combines small-amplitude vibration with different machining process to improve the process fabrication quality. It has been applied to a number of machining processes, such as turning, drilling, grinding and polishing. The emphasis on this literature is the vibration-assisted abrasive machining (VAAM), which involves with finishing and grinding processes where VAAM have been applied to hard metal, brittle material and complex geometries products like optical molds. This paper presents different vibrating units in VAAM from tool vibration to workpiece vibration, which also includes different vibrating paths from linear to ellipse. Typical hardware systems used to achieve these vibratory motions are described too.