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Description to wear debris boundaries by radar graph fractal method

Chinese Science Bulletin 2007年第16期52卷 2285-2290页

作者： LIU HongTao1,2.& GE ShiRong1 1 institute of tribology and {2. engineering,china university of Mining & technology,xuzhou 2.1008,china 2.College of Mechanical and Electrical engineering,china university of Mining & technology,xuzhou 2.1.1.,china institute of tribology and {2. engineering China University of Mining and Technology Xuzhou 221008 China

In this paper,radar graph fractal method is introduced to describe wear debris boundaries. Research results show that it is a nice way to describe wear debris boundaries. Since the longest axis is selected as the first coordinate axis,its center point selected as the center point of the radar graph,and the co-ordinate value of wear debris boundary selected as the measure parameter,the limitations existing in Yard fractal measure method can be avoided. For any wear debris,its radar graph fractal dimension value is one and only,and as the wear debris shape changes from round to strip,the radar graph fractal dimension value also changes from low to high,showing strong uniqueness and independence. Due to the fact that the researched wear debris is gotten in different wear states,the results also prove that radar graph fractal dimension value is correlated with frictional pairs work condition and wear state. Radar graph fractal method is compared with Yard fractal measure methods,and results show that ra-dar graph fractal dimension values gotten from different wear debris have enough value grads to avoid effect of errors,and provide higher sensitivity for wear debris shape. This paper also discusses the influencing factors for radar graph fractal method. With the increase of the decomposing degree value,the radar graph fractal dimension tends to keep stable at one certain value,showing the typical characteristic of the fractal theory. All this proves that radar graph fractal method is an effective description method for wear debris boundaries.

关键词：磨粒边界雷达图表分形法

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Relations between thickness of UHMWPE’s wear debris and positive pressure of tribological system

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Chinese Science Bulletin 2008年第9期53卷 1435-1443页

作者： LIU HongTao1,2.3 & GE ShiRong1,3 1 institute of tribology and {2. engineering, china university of Mining & technology, xuzhou 2.1.1., china 2.College of Mechanical and Electrical engineering, china university of Mining & technology, xuzhou 2.1.1., china 3 Biotribology Center, State Key Laboratory of tribology, xuzhou 2.1.1., china institute of tribology and {2. engineering China University of Mining & Technology Xuzhou 221116 China College of Mechanical and Electrical engineering China University of Mining & Technology Xuzhou 221116 China Biotribology Center State Key Laboratory of Tribology Xuzhou 221116 China

MiaoXAM2.5X-50X Ultrahigh Precision Surface 3D Profiler is introduced to research the relations be- tween thickness of UHMWPE’s wear debris and positive pressure of tribological system. Research re- sults show that thickness of wear debris owns evident classification, and the first grade thickness math model and the second grade thickness math model are built. By the second grade thickness math model, the true force condition in the tribological system can be gotten, and the model can be used as a tool to modify simulating parameters of the tribological system, and it is an important inspecting method to the airtight system which cannot be examined in real time. The first grade thickness math model can describe the true working load and surface condition of work piece in the tribological sys- tem, and is an effective description method for the running condition of frictional pairs. The research results at different lubricating conditions testify the relations between thicknesses of wear debris and positive pressure of the tribological system. The fractal relation between maximal thickness of wear debris and positive pressure is discussed. The conceptions of the immutability principle and charac- teristic granularity of wear debris thickness are brought forward and discussed. In conclusion, as a stable tribological parameter owning mechanical theory basis, wear debris thickness will play an im- portant part in fault diagnosis, especially for the airtight system such as artificial joint.

关键词：摩擦学磨损面厚度分形数学模型

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Friction behavior of coupling motion for natural articular cartilage by reciprocating rotation

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Chinese Science Bulletin 2009年第4期54卷 576-583页

作者： QIAN ShanHua1,2.3 & GE ShiRong1,3 1 College of Mechano-electronic engineering, china {2. of Mining & technology, xuzhou 2.1.1., china 2.institute of tribology and reliability engineering, china {2. of Mining & technology, xuzhou 2.1.1., china 3 Bio{12. Center, State Key Laboratory of {12., xuzhou 2.1.1., china College of Mechano-electronic engineering China University of Mining & Technology Xuzhou 221116 China institute of tribology and {2. engineering China University of Mining & Technology Xuzhou 221116 China Biotribology Center State Key Laboratory of Tribology Xuzhou 221116 China

Based on the irregular surface of natural cartilage configurations, the tribological characteristics of coupling motion between natural cartilage pairs were investigated by the variation of rotated offset and velocity. Contact displacement, contact load, friction force and coefficient of friction from natural cartilage pairs were measured by a UMT-2.testing machine. In order to obtain the steady part and wavy part, the contact load and contact displacement were decompounded by the five-point sliding average method. These results showed that the contact load was composed of steady load and wavy load. And the contact displacement was composed of cartilage deformation and surface outline. The steady load was similar to exterior load while natural cartilage deformation increased nonlinearly with the sliding time. Wavy load had the correlative coefficient 0.2.5 with surface outline due to the irregular surface of friction configurations. The coefficient of friction from cartilage friction configurations was less influenced by smaller magnitude in rotated parameters. A few strange summits were obtained in the area of coef-ficient of friction, and significantly related with local minimal values corresponding to the contact loads. The rotated offsets had clear impact on contact load and a slight impact on contact displacement. Larger offset produced higher wavy magnitude of the contact load. The rotated velocities played an evident role in cartilage deformation, but had a less influence on contact load. Lower velocity brought larger cartilage deformation.

关键词：软骨构造关节软骨摩擦系数软骨变形接触装

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Wettability Modification for Biosurface of Titanium Alloy by Means of Sequential Carburization

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Journal of Bionic engineering 2009年第3期6卷 219-223页

作者： Yong Luo~(1,2. Shi-rong Ge~1 Zhong-min Jin~2..institute of tribology and {2. engineering,School of Material Science and engineering,china university of Mining and technology,xuzhou 2.1008,P.R china2.institute of Medical and Biological engineering,School of Mechanical engineering,university of Leeds,Leeds LS2.9JT,UK [a]institute of tribology and {2. engineering School of Material Science and Engineering China University of Mining and Technology Xuzhou 221008 P. R China [b]Institute of Medical and Biological Engineering School of Mechanical Engineering University of Leeds Leeds LS2 9JT UK

Microporous titanium carbide coating was successfully synthesized on medical grade titanium alloy by using sequential *** in the surface morphology of titanium alloy occasioned by sequential carburization were characterized and the wettability characteristics were ***,the dispersion forces were calculated and *** results indicate that sequential carburization is an effective way to modify the wettability of titanium *** the carburization the surface dispersion force of titanium alloy increased from 76.5×10^(-3)J·m^(-2. to 105.5×10^(-3) J·m^(-2.,with an enhancement of 37.9 %.Meanwhile the contact angle of titanium alloy decreased from 83° to 71.5°,indicating a significant improvement of wettability,which is much closer to the optimal water contact angle for cell adhesion of 70°.

关键词： biotribology wettability titanium alloy sequential carburization biosurface

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Parameter identification theory of a complex model based on global optimization method

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Science china(Physics,Mechanics & Astronomy) 2008年第11期51卷 1722-1732页

作者： QU Jie1, JIN QuanLin2.& XU BingYe3 1 College of Automotive engineering, South china {2. of technology, Guangzhou 510640, china 2.Beijing Research institute of Mechanical and Electrical technology, Beijing 100083, china 3 Department of engineering Mechanics, Tsinghua {2., Beijing 100084, china 1. College of Automotive engineering South China University of Technology Guangzhou 510640 China 2. Beijing Research institute of Mechanical and Electrical technology Beijing 100083 China 3. Department of engineering Mechanics Tsinghua University Beijing 100084 China

With the development of computer technology and numerical simulation technology, computer aided {2. (CAE) technology has been widely applied to many fields. One of the main obstacles, which hinder the further application of CAE technology, is how to successfully identify the parameters of the selected model. An elementary framework for parameter identification of a complex model is provided in this paper. The framework includes the construction of objective function, the design of the optimization method and the evaluation of the identified results, etc. The parameter identification process is described in this framework, taking the parameter identification of the superplastic constitutive model considering grain growth for Ti-6Al-4V at 92.°C as an example. The objective function is the weighted quadratic sums of the difference between the experimental and computational data for the stress-strain relationship and the grain growth relationship; the designed optimization method is a hybrid global optimization method, which is based on the feature of the objective function and incorporates the strengths of genetic algorithm (GA), the Levenberg-Marquardt algorithm and the augmented Gauss-Newton algorithm. The reliability evaluation of parameter identification result is made through the comparison between the calculated and experimental results and between the theoretical values of the parameters and the identified ones.

关键词： constitutive model parameter identification theory inverse analysis global optimization

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A study on compressive shock wave propagation in metallic foams

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Science china(Physics,Mechanics & Astronomy) 2010年第2期53卷 279-287页

作者： WANG ZhiHua1,2.ZHANG YiFen2.REN HuiLan1 & ZHAO LongMao2.1 State Key Laboratory of Explosion Science and technology,Beijing institute of technology,Beijing 100081,china 2.institute of Applied Mechanics and Biomedical engineering,Taiyuan university of technology,Taiyuan 03002.,china 1. State Key Laboratory of Explosion Science and technology Beijing Institute of Technology Beijing 100081 China2. Institute of Applied Mechanics and Biomedical Engineering Taiyuan University of Technology Taiyuan 030024 China

Metallic foam can dissipate a large amount of energy due to its relatively long stress plateau,which makes it widely applicable in the design of structural crashworthiness. However,in some experimental studies,stress enhancement has been observed when the specimens are subjected to intense impact loads,leading to severe damage to the objects being protected. This paper studies this phenomenon on a 2. mass-spring-bar model. With the model,a constitutive relationship of metal foam and corresponding loading and unloading criteria are presented; a nonlinear kinematics equilibrium equation is derived,where an explicit integra-tion algorithm is used to calculate the characteristic of the compressive shock wave propagation within the metallic foam; the effect of heterogeneous distribution of foam microstructures on the shock wave features is also included. The results reveal that under low impact pulses,considerable energy is dissipated during the progressive collapse of foam cells,which then reduces the crush of objects. When the pulse is sufficiently high,on the other hand,stress enhancement may take place,especially in the heterogeneous foams,where high peak stresses usually occur. The characteristics of compressive shock wave propagation in the foam and the magnitude and location of the peak stress produced are strongly dependent on the mechanical properties of the foam material,amplitude and period of the pulse,as well as the homogeneity of the microstructures. This research provides valuable insight into the reliability of the metallic foams used as a protective structure.

关键词： aluminum foam heterogeneous intensive pulse loading stress enhancement

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reliability analysis of ship structure system with multi-defects

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Science china(Physics,Mechanics & Astronomy) 2010年第11期53卷 2113-2124页

作者： AN Hai 1,AN WeiGang 1 & ZHAO WeiTao 2.1 School of Aerospace and Civil engineering,Harbin engineering {2.,Harbin 150001,china 2.School of Aeronautics and Astronautics,Shenyang institute of Aeronautical engineering,Shenyang 110034,china 1. School of Aerospace and Civil engineering Harbin Engineering University Harbin 150001 China2. School of Aeronautics and Astronautics Shenyang Institute of Aeronautical Engineering Shenyang 110034 China

This paper analyzes the influence of multi-defects including the initial distortions,welding residual stresses,cracks and local dents on the ultimate strength of the plate element,and has worked out expressions of reliability calculation and sensitivity analysis of the plate *** analysis is made for the system with multi-defects plate *** mechanism,failure paths and the calculating approach to global reliability index are also worked *** plate elements with multi-defects fail,the formula of reverse node forces which affect the residual structure is deduced,so are the sensitivity expressions of the system reliability *** ensures calculating accuracy and rationality for reliability analysis,and makes it convenient to find weakness plate elements which affect the reliability of the structure ***,for the validity of the approach proposed,we take the numerical example of a ship cabin to compare and contrast the reliability and the sensitivity analysis of the structure system with multi-defects with those of the structure system with no *** approach has implications for the structure design,rational maintenance and renewing strategy.

关键词： initial distortions welding residual stresses cracks and local defects ultimate strength reverse node forces sensitivity expression reliability analysis

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A new method for spatio-temporal prediction of rainfall-induced landslide

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Science china Earth Sciences 2006年第4期49卷 421-430页

作者： DING Jixin1,2. YANG Zhifa2. SHANG Yanjun2. ZHOU Shenghua1 & YIN Juntao3 1. china Non-ferrous Metals Resource Geological Survey, Beijing 100012. china 2. {2. of Geology and Geophysics, Chinese Academy of Sciences, Key Laboratory of engineering Geomechanics, Beijing 10002., china 3. School of Geoscience & Environmental engineering, Central South university, Changsha 410083, china 1. china Non-ferrous Metals Resource Geological Survey Beijing 100012 China 2. institute of Geology and Geophysics Chinese Academy of Sciences Key Laboratory of Engineering Geomechanics Beijing 100029 China 3. School of Geoscience & Environmental engineering Central South University Changsha 410083 China

Geological condition and rainfall are two most principal conditions inducing landslides in the Chongqing region. By analyzing the forming conditions of rainfall-induced landslides, a new method for spatio-temporal prediction of rainfall-induced landslide is brought forward on the basis of grading and overlapping geological condition and rainfall factor in this paper. At first, semi-quantitative assessment and grading for the geological condition of a certain area or slope can be carried out with the multi-factor interactive matrix. Then the severity of rainfall in that area is grading according to the maximum daily rainfall and the total rainfall in a rainfall course. Finally, the “landslide probability judgement factor” can be worked out through grading and overlapping “geological condition influenc- ing factor” and “rainfall influencing factor”, by which the landslide can be graded into 4 grades, they are landslide extremely easily happening, landslide easily happening, landslide difficultly happening and landslide hardly ever happening respectively. More accurate spatio-temporal prediction of rain- fall-induced landslides can come true on the ground of detailed geological survey of some dangerous slopes in an area and more precise weather forecast. Finally, the reliability and feasibility of carrying out the spatio-temporal prediction of rainfall-induced landslides with the method of “two factors” grading and overlapping are validated by the example of Jipazi landslide.

关键词： rainfall-induced landslide, geological condition, rainfall, two factors, grading and overlapping, interactive matrix, spatio-temporal prediction.

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ON DESIGN METHOD OF THE PRECISION CAM PROFILE WITH RANDOM PROCESSING ERRORS

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Chinese Journal of Mechanical engineering 2003年第1期16卷 10-12页

作者： Zhao ZhisuMechatronics engineering andAutomation institute,National {2. ofDefense technology,Changsha 410073, china Mechatronics engineeringand Automation institute National University of DefenseTechnology Changsha 410073

Based on probability and statistic, a design method of precision cam profileconcerning the influence of random processing errors is advanced. Combining the design with theprocess, which can be used to predict that cam profiles will be successfully processed or not in thedesign stage, design of the cam can be done by balancing the economization and reliability. Inaddition, an fuzzy deduction method based on Bayers formula is advanced to estimate processingreasonable of the designed precision cam profile, and it take few samples.

关键词： Cam profiles design Random processing errors Probability and statistic

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A constitutive model of frozen soil with damage and numerical simulation for the coupled problem

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Science china(Physics,Mechanics & Astronomy) 2010年第4期53卷 699-711页

作者： ZHU ZhiWu, NING JianGuo& MA Wei 1 School of Mechanics and engineering, Southwest Jiaotong university, Chengdu 610031,{2. 2.State Key Laboratory of Explosion Science and technology, Beijing institute of technology, Beijing 100081,{2. 3 Key Laboratory of Frozen Soil engineering, CAREERI, CAS, Lanzhou 730000,{2. 1. School of Mechanics and engineering Southwest Jiaotong University Chengdu 610031 China2. State Key Laboratory of Explosion Science and Technology Beijing Institute of Technology Beijing 100081 China3. Key Laboratory of Frozen Soil Engineering CAREERI CAS Lanzhou 730000 China

Based on the microcosmic mechanics of composite materials, an elastic constitutive model for frozen soil with damage is presented. For frozen sandy soil with a range of ice contents and under a range of temperature conditions, quantitative results determined by this constitutive model agree with practically measured stress-strain curves. After numerically simulating the coupled water, temperature and stress fields of channel frozen and frozen roadbed using a self-developed finite-element routine, more accurate and practical calculation results for the temperature field coupled with stress, displacement and strain fields are obtained; the results match predictions and tests undertaken by earlier researchers. Our results support the reliability of our routine for calculating interdependent physical quantities of frozen soil and for describing the relationships between them. Our program can offer necessary constraints for engineering design and construction in permafrost regions.

关键词： frozen soil microcosmic mechanics roadbed coupling stress field

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