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Friction 2024年第2期12卷 271-290页

作者： shaohua li Xiaohui liN Shuyun JIANG School of Mechanical Engineering Southeast UniversityNanjing 211189China

Bubbly oil lubrication is a type of lubrication ***,the lubrication model of the bubbly oil has not been thoroughly *** paper aims to investigate the modelling for bubbly oil lubrication considering the interfacial effect and thermal effect,and a theoretical model is established based on the theory of multiphase *** interfacial and thermal effects on the static characteristics of a thrust bearing are analyzed.A test rig for the thrust bearing is developed to measure the static characteristics of the bearing under bubbly oil *** results show that the bearing static characteristics,*** temperature rise,film thickness,friction torque,and volume flow,increase with consideration of three interfacial effects;the bearing temperature rise increases but the film thickness,friction torque,and volume flow rate decrease with consideration of the three thermal effects;the thermal effect on the bearing static characteristics is greater than the interfacial effect.

关键词： bubbly oil lubrication theory of multiphase mixtures interfacial effect thermal effect fluid bearing

Fracture spacing behavior in layered rocks subjected to different driving forces： a numerical study based on fracture infilling process

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Frontiers of Earth Science 2014年第4期8卷 472-489页

作者： lianchong li shaohua li Chun'an TANG School of Civil Engineering Dalian University of Technology Dalian 116024 China

Natural layered rocks subjected to layerparallel extension typically develop an array of opening- mode fractures with a remarkably regular spacing. This spacing often scales with layer thickness, and it decreases as extension increases until fracture saturation is reached. To increase the understanding of how these opening-mode fractures form in layered rocks, a series of 2D numerical simulations are performed to investigate the infilling process of fractures subjected to different driving forces. Numerical results illustrate that any one of the following could be considered as a driving force behind the propagation of infilling fractures： thermal effect, internal fluid pressure, direct extension loading, or pure compressive loading. Fracture spacing initially decreases with loading process, and at a certain ratio of fracture spacing to layer thickness, no new fractures nucleate （saturated）. Both an increase in the opening of the infilled fractures and interface delamination are observed as mechanisms that accommodate additional strain. Interface debonding stops the transition of stress from the neighboring layers to the embedded central layer, which may preclude further infilling of new fractures. Whatever the driving force is, a large overburden stress and a large elastic contrast between the stiff and soft layers （referred to as a central or fractured layer and the top and bottom layers） are key factors favoring the development of tensile stress around the infilled fractures in the models. Fracture spacing is expected to decrease with increasing overburden stress. Numerical results highlight the fracturing process developed in heterogeneous and layered sedimentary rocks which provides supplementary information on the stress distribution and failure-induced stress redistribution., It also shows, in detail, the propagation of the fracture zone and the interaction of the fractures, which are impossible to observe in field and are difficult to consider with static st

关键词： opening-mode fractures fracture spacing,driving force numerical simulation heterogeneity

Time-Periodic Fitzhugh-Nagumo Equation and the Optimal Control Problems

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Chinese Annals of Mathematics,Series B 2021年第3期42卷 471-486页

作者： Hanbing liU Wenqiang LUO shaohua li School of Mathematics and Physics China University of Geosciences(Wuhan)Wuhan430074China

In this work, the authors considered the periodic optimal control problem of Fitzhugh-Nagumo equation. They firstly prove the existence of time-periodic solution to Fitzhugh-Nagumo equation. Then they show the existence of optimal solution to the optimal control problem, and finally the first order necessary condition is obtained by constructing an appropriate penalty function.

关键词： Fitzhugh-Nagumo equation Time-periodic Optimal control

Defect Analysis and Innovation Design of Synchronizer for Clutchless Automatic Mechanical Transmission

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Chinese Journal of Mechanical Engineering 2022年第1期35卷 238-254页

作者： lipeng Zhang Yunao Peng Haojie Yang shaohua li Hebei Key Laboratory of Special Delivery Equipment Yanshan UniversityQinhuangdao 066004China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao UniversityShijiazhuang 050043China

The synchronizer is a key component of automatic mechanical transmission(AMT)equipped in electric vehicles,but the inertial lock-ring synchronizer(ILRS)commonly used there is not suitable especially for pure electric vehicles without a clutch because of big shift *** make the shifting process rapid and smooth,a new synchronizer named pressure-controllable friction ring synchronizer(PCFRS)was ***,the inevitable shortcoming of ILRS was verified by simulation and ***,the mechanical characteristics and advantages of the new synchronizer over ILRS were ***,the formulations describing the dynamic transmission based on the working mechanism of the PCFRS were ***,the shifting simulation results with PCFRS and ILRS based on the same operating conditions were compared and *** research shows that the PCFRS can meet the main shifting evaluation index of an AMT without complex control methods,as well as it takes only 0.2406 s to finish the comfortable and zero-speed-difference *** shifting quality of PCFRS is better than that of the *** lays a foundation for using the new synchronizer as a part of clutchless AMTs equipped in pure electric vehicles.

关键词： Electric vehicle Clutchless automatic mechanical transmission Inertial lock-ring synchronizer Pressure-controllable friction ring synchronizer Mechanical characteristics Shifting quality

Dynamics of vehicle-pavement coupled system based on a revised flexible roller contact tire model

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Science China(Technological Sciences) 2009年第3期52卷 721-730页

作者： YANG ShaoPu li shaohua LU YongJie School of Mechanical Engineering Shijiazhuang Railway InstituteShijiazhuang 050043China

A revised flexible roller contact tire model (RFRC tire model) is proposed, which considers not only the geometric and flexible filtering effect, but also tire damping and pavement displacement. A vehi- cle-pavement coupled system is modeled as a two DOF oscillator moving along a simply supported beam on a linear viscoelastic foundation. By using the Galerkin’s and Direct Integral method, dynamical responses of the vehicle-pavement coupled system are obtained based on the RFRC tire model and the traditional single point contact tire model (SPC tire model). The simulation results are compared with test data and the validity of the proposed RFRC tire model is verified. Differences between the two models are also investigated. It is found that the dynamical behaviors for both models agree with each other quite well when road surface roughness is a long harmonic wave. On the other hand, they are different under short harmonic wave or impulse road excitation. Thus the RFRC tire model should be used to compute the tire force and investigate dynamical responses of vehicle and pavement.

关键词： tire model dynamics flexible roller contact vehicle-pavement coupled system viscoelastic foundation

Research on dynamics of a class of heavy vehicle-tire-road coupling system

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Science China(Technological Sciences) 2011年第8期54卷 2054-2063页

作者： LU YongJie YANG ShaoPu li shaohua School of Mechanical Engineering Shijiazhuang Tiedao University Shijiazhuang 050043 China School of Mechanical Electronic and Control Engineering Beijing Jiaotong University Beijing 100044 China

The dynamic tire force of heavy vehicle is a primary reason for road damage. This paper presents a mathematic model to restore the interacting process of vehicle-tire-road system and tries to find out the mechanics of interaction. A nonlinear tri-axle vehicle model with IBS (integral balanced suspension) is firstly proposed based on the detailed analysis of structural features of a heavy vehicle (DFL1250). The results indicate that the nonlinearities in the vehicle suspension contribute to improvement of ride comfort and to the reduction of dynamic tire force. Furthermore, an FRC (flexible rolling contact) tire model with the enveloping characteristics is added into the IBS model. The tire model considers both the tire contact history with rough road profile and the uneven distribution characteristics of vertical load. The FRC model is able to remove medium and high vibration components from uneven road profile due to its filtering feature. It is expected that these results could supply a new idea for vehicle-road interaction research.

关键词： heavy vehicle balanced suspension enveloping property nonlinear coupling system stochastic road excitation

On the parameterized vertex cover problem for graphs with perfect matching

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Science China(Information Sciences) 2014年第7期57卷 105-116页

作者： WANG JianXin li WenJun li shaohua CHEN JianEr School of Information Science and Engineering Central South University Department of Computer Science and Engineering Texas A&M UniversityCollege Station

A vertex cover of an n-vertex graph with perfect matching contains at least n/2 *** this paper,we study the parameterized complexity of the problem vc-pm*that decides if a given graph with perfect matching has a vertex cover of size bounded by n/2+*** first present an algorithm of running time O*(4k)for a variation of the vertex cover problem on K¨onig graphs with perfect *** algorithm combined with the iterative compression technique leads to an algorithm of running time O*(9k)for the problem vc-pm*.Our result improves the previous best algorithm of running time O*(15k)for the vc-pm*problem,which reduces the problem to the almost 2-sat problem and solves the latter by Razgon and O’Sullivan’s recent algorithm.

关键词： NP-complete parameterized algorithm vertex cover iterative compression

Analytical solutions of ground settlement induced by yaw in a space curved shield tunnel

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Underground Space 2023年第6期13卷 86-103页

作者： Jiannan Xie Pengfei li Mingju Zhang Fei Jia shaohua li Key Laboratory of Urban Security and Disaster Engineering Ministry of EducationBeijing University of TechnologyBeijing 100124China China Railway No.3 Engineering Group No.4 Engineering Co. Ltd.Beijing 102300China China Railway 15th Bureau Group Co. Ltd.Shanghai 200070China

This paper aims to provide the analytical solutions of the ground settlement for a space curved shield tunnel in the case of yaw *** inducements include ground loss and construction loads,and two corresponding analytical models have been proposed in this ***-dimensional image theory has been adopted to calculate the ground settlement due to ground *** parameters are introduced into the calculation model to deduce the relevant laws of the ground *** on modified Mindlin solutions,analytical models are established to calculate the ground settlement induced by construction loads,such as the frontal additional thrust,axial friction of shield shell,and the grouting *** method of calculating the position of the shield machine in the ground is refined,and the influence area of construction loads from the shield machine is ***,the obtained solutions are validated by a numerical model and field ***,a comparison reveals that the proposed model is the composition of three classical analytical models,thus it excels them in solving the problem ***,parametric analyses of yaw are conducted to examine yaw angle and pitch angle on ground *** proposed model can effectively predict ground settlement caused by the spatial linear shield tunneling process.

关键词： Shield tunnel Space line Yaw excavation Ground loss Construction load Ground settlement

Influence of vehicle-road coupled vibration on tire adhesion based on nonlinear foundation

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Applied Mathematics and Mechanics(English Edition) 2021年第5期42卷 607-624页

作者： Junning ZHANG Shaopu YANG shaohua li Yongjie LU Hu DING School of Traffic and Transportation Shijiazhuang Tiedao UniversityShijiazhuang 050043China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang 050043China Shanghai Institute of Applied Mathematics and Mechanics Shanghai Key Laboratory of Mechanics in Energy EngineeringShanghai UniversityShanghai 200072China

The influence of pavement vibration on tire adhesion is of great significance to the structure design of vehicle and *** adhesion between tire and road is the key to studying vehicle dynamics,and the precise description of tire adhesion affects the accuracy of dynamic vehicle ***,in most models,only road roughness is considered,and the pavement vibration caused by vehicle-road interaction is *** this paper,a vehicle is simplified as a spring-mass-damper oscillator,and the vehicle-pavement system is modeled as a vehicle moving along an Euler-Bernoulli beam with finite length on a nonlinear *** road roughness is considered as a sine wave,and the shear stress is ignored on the *** to the contact form between tire and road,the LuGre tire model is established to calculate the tire adhesion *** Galerkin method is used to simplify the partial differential equations of beam vibration into finite ordinary differential equations.A product-to-sum formula and a Dirac delt function are used to deal with the nonlinear term caused by the nonlinear foundation,which realizes the fast and accurate calculation of super-high dimensional nonlinear ordinary differential *** addition,the dynamic responses between the coupled system and the traditional uncoupled system are compared with each *** obtained results provide an important theoretical basis for research on the influence of vehicle-road coupled vibration on tire adhesion.

关键词： vehicle system dynamics vehicle-road coupled vibration LuGre tire model Galerkin method

Parametric analysis of a packed bed thermal storage device with phase change material capsules in a solar heating system application

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Building Simulation 2021年第3期14卷 523-533页

作者： Long Gao Gegentana Junchao Bai Baizhong Sun Deyong Che shaohua li School of Energy and Power Engineering Northeast Electric Power UniversityJilin 132012China

The goal of this study is to investigate the effect of key design parameters on the thermal performance of the packed bed heat storage device by numerical calculation.A one-dimensional,non-equilibrium packed bed latent heat storage mathematical model was established and the applicability of the model was *** results demonstrate that the inlet temperature of the heat transfer fluid(HTF)had the greatest influence on each *** the inlet temperature increased from 333 K to 363 K,exergy destruction increased threefold,effective heat storage time decreased by 67%,effective heat storage increased by 38%,and exergy efficiency decreased by 11%.The decrease of the capsule diameter had a positive effect on each evaluation *** to the sensitivity analysis,the order of importance of each parameter within their variation range was HTF inlet temperature,HTF flow rate,PCM capsule size and PCM initial temperature.

关键词： packed bed thermal energy storage solar heating system performance evaluation parametric analysis