Bio: Jianrong Tan is an academic researcher from Zhejiang University. The author has contributed to research in topics: Shear rate & Traction (engineering). The author has an hindex of 2, co-authored 2 publications receiving 5 citations.
TL;DR: In this article, the multiaxial Fatemi-Socie fatigue criterion is adopted to study the contact fatigue in a spherical asperity subjected to cyclic elastic-plastic normal loading.
Abstract: Surface fatigue resulting from cyclic contact loading is a main reason for the rough surface wear. Since a rough surface consists of many asperities, the fatigue in one asperity is investigated. The multiaxial Fatemi–Socie fatigue criterion is adopted to study the contact fatigue in a spherical asperity subjected to cyclic elastic-plastic normal loading. The fatigue damage in the asperity is predicted. The maximum fatigue damage occurs at the edge of the maximum contact area. Two typical patterns are found for the fatigue damage distribution. Locations and orientations of fatigue microcrack initiation are also identified. Finally, future research directions are discussed.
TL;DR: In this paper, a new model of traction in elastohydrodynamically lubricated contact is presented to study shear stress distributions, and full numerical analyses of elliptical contacts under rolling and sliding are presented.
Abstract: A new model of traction in elastohydrodynamically lubricated contact is presented to study shear stress distributions. Results of full numerical analyses of elliptical contacts under rolling and sliding are presented. This study is confined to elastohydrodynamically lubricated contacts of relatively low load. Effects of dimensionless parameters such as speed, normal load, and elliptical parameter and coefficient of limiting shear stress on shear stress distributions have been analyzed. Moreover, the influence of slide-roll ratio on visualized shear stress in EHD contacts has been studied. It has been found that the higher slide-roll ratios induce higher maximum shear stress. Shear stresses in fluid film and those on surfaces vary with many factors that reveal the mechanism of traction in EHD conjunction zones.
TL;DR: In this article , the effect of lubricant viscosity on dynamics of a high-precision spur gear pair with near-zero backlash was investigated under deterministic and uncertain conditions via a tribo-dynamic model.
TL;DR: In this article, a simplified model of tapered roller bearings consisting of one inner raceway, one outer raceway and a tapered rolling bearing was established, in which the interaction of several heat sources was ignored.
Abstract: In the field of aerospace, high-speed trains and automobile, etc, analysis of temperature filed and scuffing failure of tapered roller bearings are more important than ever, and the scuffing failure of elements of such rolling bearings under heavy load and high speed still cannot be effectively predicted yet. A simplified model of tapered roller bearings consisted of one inner raceway, one outer raceway and a tapered roller was established, in which the interaction of several heat sources is ignored. The contact mechanics model, temperature model and model of scuffing failure are synthesized, and the corresponding computer programs are developed to analyze the effects of bearings parameters, different material and operational conditions on thermal performance of bearings, and temperature distribution and the possibility of surface scuffing are obtained. The results show that load, speed, thermal conductivity and tapered roller materials influence temperature rise and scuffing failure of bearings. Ceramic material of tapered roller results in the decrease of scuffing possibility of bearings to a high extent than the conventional rolling bearing steel. Compared with bulk temperature, flash temperature on the surfaces of bearing elements has a little influence on maximum temperature rise of bearing elements. For the rolling bearings operated under high speed and heavy load, this paper proposes a method which can accurately calculate the possibility of scuffing failure of rolling bearings.
01 Jan 2004
TL;DR: In this paper, the authors present a table of acknowledgments for the work of the authors of this paper: https://github.com/mcclouda/blog.
Abstract: iv Dedication vi Acknowledgments vii Table of
TL;DR: In this paper, a hybrid optimization method was developed for solving many-objective optimization problems of low specific speed centrifugal pumps (LSSCP) in district energy systems to promote the integration of renewable energy.
Abstract: Low specific speed centrifugal pumps (LSSCP) are widely utilized in district energy systems to promote the integration of renewable energy. However, the performance of LSSCP becomes inefficient due to harsh operating conditions resulting in substantial increase in energy consumption. Many-objective optimization is significant in improving the performance of LSSCP and promoting the sustainability of district energy systems. Among the existing optimization methods, global optimization methods are limited by high computational cost when solving many-objective optimization problems, and gradient-based optimization methods face difficulties in locating the global optimum. In the present study, a hybrid optimization method was developed for solving many-objective optimization problems of LSSCP. The LSSCP optimization result of the hybrid algorithm was compared with that of the non-dominated sorting genetic algorithm (NSGA), so as to demonstrate the capacity of the proposed method. In the designed flow condition without cavitation, the hydraulic efficiency obtained by the hybrid optimization algorithm was found to be 9.5%, 5.4%, and 4.7% higher than those of the original, NSGA-II, and NSGA-III optimized results, respectively. The shaft power was 10.3%, 8.7% and 5.1% less than said three optimized results. The maximum turbulent kinetic energy in the flow passage obtained from the hybrid optimization was only 2.2 J/kg, which was 67% and 46% less than that of the NSGA-II and NSGA-III optimized results, respectively. In the designed flow condition with cavitation, the net positive suction head critical optimized by the hybrid model was 0.857 m, which was substantially reduced compared with the original and NSGA- II optimized results.
TL;DR: In this article , a vibration separation methodology compensated by a time-varying transfer function (TVTF-VS) was proposed to diagnose non-hunting tooth planetary gearboxes.
Abstract: Due to planetary movement of planet gears, the vibration signal perceived by a stationary sensor is modulated and difficult to diagnose. This paper proposed a vibration separation methodology compensated by a time-varying transfer function (TVTF-VS), which is a further development of the vibration separation (VS) method in the diagnosis of non-hunting tooth planetary gearboxes. On the basis of VS, multi-teeth VS is proposed to extract and synthesize the meshing signal of a planet gear using a single transducer. Considering the movement regularity of a planetary gearbox, the time-varying transfer function (TVTF) is represented by a generalized expression. The TVTF is constructed using a segment of healthy signal and an evaluation indicator is established to optimize the parameters of the TVTF. The constructed TVTF is applied to overcome the amplitude modulation effect and highlight fault characteristics. After that, experiments with baseline, pitting, and compound localized faults planet gears were conducted on a non-hunting tooth planetary gearbox test rig, respectively. The results demonstrate that incipient failure on a planet gear can be detected effectively, and relative location of the local faults can be determined accurately.