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Comparative Study on the Complex Eigenvalue Prediction of Brake Squeal by Two Infinite Element Modeling Approaches

Chinese Journal of Mechanical Engineering 2010年第3期23卷 383-390页

作者： CHEN Guangxlong WU Pingbo DAI Huanyun zhou zhongrong State Key Laboratory of Traction Power Southwest Jiaotong University Chengdu 610031 China

The complex eigenvalue analysis is currently a common approach to predict squealing vibration and noise. There are two methods for modeling friction contact in the complex eigenvalue analysis of friction systems. In one method, contact springs are used to simulate friction contact. In another method, no contact spring is used. However, it has been uncertain whether these two modeling methods can predict approximately identical results. In order to clarify the uncertainty, two finite element models of the same brake system for the brake squeal prediction are established and simulated by using ABAQUS and NASTRAN software tools, respectively. In the ABAQUS model, friction coupling is applied to determine normal contact force and no contact spring is assumed. Whilst in the NASTRAN model, the contact spring is assumed by the penalty method to simulate contact connection. Through the numerical simulations, it is recognized that even if the same mesh geometry is applied, generally, these two finite element approaches are not capable of predicting approximately identical unstable frequencies. The ABAQUS approach can predict instabilities of high frequency up to 20 kHz or more, while the NASTRAN approach can only predict some instabilities of high frequency, not all. Moreover, the simulation results also show that both the contact spring stiffness and mesh size have influences to some extent on the prediction results of squeal. The present comparative work illuminates that the modeling method without contact springs is more suitable to predict squealing vibration and noise, comparing to the modeling method with contact springs. It is proposed that one should prefer using the modeling method without contact springs to predict squealing vibration and noise. The proposed study provides the reference for predicting squealing vibration and noise.

关键词： friction brake squeal noise finite element

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Influence of two polyphenols on the structure and lubrication of salivary pellicle:An in vitro study on astringency mechanism

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Friction 2022年第1期10卷 167-178页

作者： Lei LEI Yue TANG Jing ZHENG Genlei MA zhongrong zhou Tribology Research Institute Key Laboratory of Advanced Technologies of MaterialsMinistry of EducationSouthwest Jiaotong UniversityChengdu 610031China

This study investigated the influence of two polyphenols on the structure and lubrication of the salivary pellicle,aiming to extend the understanding of astringency *** salivary pellicle was prepared by the adsorption of human whole saliva on the enamel ***-astringency catechin and high-astringency tannic acid were used as *** changes induced by the two polyphenols in the structure and lubrication of the salivary pellicle were examined using quartz crystal microbalance with dissipation(QCM-D)and nano-indentation/scratch *** salivary pellicle suffers from changes in structure and physical properties owing to protein dehydration and protein-polyphenol complexation when encountering polyphenolic molecules,causing increases in the roughness and contact angle but a decrease in the load-bearing ***,the lubrication performance of the salivary pellicle is impaired,leading to an increase and fluctuation of the friction *** intensity of astringency has a strong positive correlation with the water contact angle,surface roughness,and friction coefficient of the salivary *** summary,astringency is a tactile perception driven by the roughness and wettability of the salivary pellicle rather than oral lubrication,and increased intraoral friction is an inevitable consequence of *** findings of this study will help promote and assist the objective evaluation of astringency.

关键词： salivary impaired string

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The correlation between biotribological function and structural characteristics of bamboo rat teeth

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Biosurface and Biotribology 2022年第4期8卷 323-328页

作者： Zhenwu Ning zhongrong zhou Jing Zheng Tribology Research Institute Key Laboratory of Advanced Technologies of MaterialsMinistry of EducationSouthwest Jiaotong UniversityChengduChina

Chinese bamboo rats consume a diet that consists mainly mechanically demanding *** ability of the rats to process food depends on the capacity of their teeth to resist wear during biting and *** mechanisms of the bamboo rat teeth were determined by investigating and correlating the structure and tribological properties of the *** rat's incisor has a cutting-edge cusp and outer enamel iron pigmentation,making the teeth harder,more resistant to acid attacks,and improving the resistance to ***,the incisor is designed to *** complex morphology at the macroscale,and the three-dimensional fabric body formed by densely packed rods and inter-rods at the microscale of molar enamel benefit molar rapid capture and effective breaking of bamboo,resisting the high stresses required to process bamboo without *** results of the structure-function relations of bamboo rat teeth in this study may provide new ideas for improving plant cutting and grinding tools.

关键词： bamboo rat teeth biotribological function enamel mechanical properties microstructure

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Restoration of enamel anti-wear properties via remineralization: Role of occlusal loading

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Friction 2022年第11期10卷 1838-1850页

作者： Jiapin PENG Lei LEI Heng XIAO Dan YANG Jing ZHENG zhongrong zhou Tribology Research Institute Key Laboratory of Advanced Technologies of MaterialsMinistry of EducationSouthwest Jiaotong UniversityChengdu 610031China

In this in vitro study,the restoration of acid-eroded enamel surface morphology and anti-wear properties under two conditions,mono-remineralization(treated with remineralization alone)and impact-remineralization(treated with cyclic impact followed by remineralization),are characterized to determine the effect of occlusal loading on enamel *** with the mono-remineralized surface,the impact-remineralized surface demonstrates better anti-wear performance,as manifested by a higher hardness and elastic modulus,as well as a lower friction coefficient and wear *** on the eroded enamel surface induces the fragmentation of hydroxyapatite nanoparticles,which aids crystal deposition and fusion during subsequent *** summary,owing to the enamel microstructure,occlusal loading can promote the restoration of enamel anti-wear properties by enhancing *** enhancement through occlusalloading-induced nanoparticle fragmentation plays a significant role in preventing human teeth from excessive wear.

关键词： human tooth enamel anti-wear properties remineralization occlusal loading nanoparticle fragmentation

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Protective effects of two food hydrocolloids on dental erosion:Nanomechanical properties and microtribological behavior study

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Friction 2021年第2期9卷 356-366页

作者： Heng XIAO Liang ZHENG Wei HAN Rui WU Jing ZHENG zhongrong zhou Tribology Research Institute Key Laboratory of Advanced Technologies of MaterialsMinistry of EducationSouthwest Jiaotong UniversityChengdu 610031China Institute of Oceanographic Instrumentation Shandong Provincial Key Laboratory of Marine Monitoring Instrument and Equipment TechnologyQilu University of Technology(Shandong Academy of Sciences)Qingdao 266061China

In this study,the protective effects of two food hydrocolloids,Xanthan gum and Arabic gum,on dental erosion are investigated from the perspective of the nanomechanical properties and microtribological behavior of acid-eroded *** specimens prepared from extracted human teeth were immersed in citric acid solution(CAS),CAS with 0.03%w/v Xanthan gum and CAS with 0.03%w/v Arabic gum,respectively,for 10 min to obtain three groups of eroded *** nanomechanical properties and microtribological behavior of enamel were examined using nano-indentation/scratch *** results show that compared with Arabic gum,Xanthan gum inhibits enamel surface demineralization and acid permeation more effectively because of a more uniform and denser adsorption on the surface of the *** impairment of the nanomechanical and microtribological properties of the enamel surface by acid erosion is mitigated more significantly by adding trace amounts of Xanthan gum than Arabic *** summary,adding trace food hydrocolloids reduces enamel surface demineralization and inhibits acid permeation to mitigate the influence of erosion on the mechanical and tribological properties of *** adsorption state of food hydrocolloids is the determining factor in the permeability of acid agents into the enamel and plays a significant role in preventing dental erosion.

关键词： dental erosion Xanthan gum Arabic gum nanomechanical properties microtribological behavior

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A NOVEL BOUNDARY INTEGRAL EQUATION METHOD FOR LINEAR ELASTICITY--NATURAL BOUNDARY INTEGRAL EQUATION

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Acta Mechanica Solida Sinica 2001年第1期14卷 1-10页

作者： Niu zhongrong Wang Xiuxi zhou Huanlin Zhang Chenli Department of Mechanics University of Science and Technology of China Hefei 230026 China Department of Mechanics University of Science and Technology of China Hefei 230026 China Institute of Applied Mechanics Hefei University of Technology Hefei 230009 China Institute of Applied Mechanics Hefei University of Technology Hefei 230009 China

Th boundary integral equation (BIE) of displacement derivatives isput at a disadvan- tage for the difficulty involved in the evaluationof the hypersingular integrals. In this paper, the op- erators δ_ijand ε_ij are used to ac to the derivative BIE. The boundarydisplacements tractions and displacement derivatives are transformedinto a set of new boundary tensors as boundary variables. A new BIEformulation termed natural boundary integral equation (NBIE) isobtained. The NBIE is applied to solving two-dimensional elasticityproblems. In the NBIE only the strongly singular inte- grals arecontained. The Cauchy principal value integrals occurring in the NBIEare evaluated. A combination of the NBIE and displacement BIE can beused to directly calculate the boundary stress- es. The numericalresults of several examples demonstrate the accuracy of the NBIE.

关键词： BEM natural BIE elasticity

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Automatic modeling together with numerical simulation of the different-scale microstructures of human tooth enamels

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Science China(Technological Sciences) 2017年第9期60卷 1381-1399页

作者： LIU Tao DENG Qiang YANG Dan ZHENG Jing LIU JianTao zhou zhongrong School of Mechanical Engineering Southwest Jiaotong University Chengdu 610031 China

The present paper aims to develop an automatical strategy for generating accurate different-scale microstructures of human tooth enamels(HTEs),and to elaborate a numerical scheme for simulating their elastic *** first,the strong governing formulation of these microstructures is briefly constructed,and the relevant weak formulation is then deduced based on the virtual work ***,a subdividing approach,which cuts the elements intercepted by the interfaces between distinct phases automatically,is established with the aid of the level set method(LSM),and the discrete counterpart of the governing formula is obtained by combining the weak formulation derived and a discretized *** be noted,two silent merits are found when the elaborated strategy is applied:(1) the continents constituting the microstructures of different scales can be arbitrarily-shaped and conveniently reproduced;(2) the periodic boundary condition commonly employed can be enforced on the external surfaces of representative unit cells(RUCs) with no ***,a boundary value problem(BVP) involving a simplified HTE nanostructure is designed,analytically solved,and hereafter applied to verify the correctness of the proposed *** is observed that both the displacement and stress predictions by the computational approach are in good agreement with the relevant analytical results irrespective of the material combinations ***,discussions are made on the influence of material organizations of both the 2D and 3D HTE microstructures at the ultrastructural and repeated rod levels,and some concluding remarks are drawn.

关键词： tooth enamel level set method automatic modefing numerical simulation microstructure

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Simultaneous energy harvesting and tribological property improvement

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Friction 2021年第5期9卷 1275-1291页

作者： Xiaofan WANG Jiliang MO Huajiang OUYANG Zaiyu XIANG Wei CHEN zhongrong zhou Tribology Research Institute Southwest Jiaotong UniversityChengdu 610031China School of Engineering University of LiverpoolLiverpool L693GHUK

In this study,piezoelectric elements were added to a reciprocating friction test bench to harvest friction‐induced vibration *** such as vibration acceleration,noise,and voltage signals of the system were measured and *** results show that the piezoelectric elements can not only collect vibration energy but also suppress friction‐induced vibration noise(FIVN).Additionally,the wear of the friction interface was examined via optical microscopy(OM),scanning electron microscopy(SEM),and white‐light interferometry(WLI).The results show that the surface wear state improved because of the reduction of *** order to analyze the experimental results in detail and explain them reasonably,the experimental phenomena were simulated ***,a simplified two‐degree‐of‐freedom numerical model including the original system and the piezoelectric system was established to qualitatively describe the effects,dynamics,and tribological behaviors of the added piezoelectric elements to the original system.

关键词： piezoelectric friction‐induced vibration(FIV) energy harvester wear state contact

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Enamel matrix proteins in promoting saliva lubrication

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Friction 2024年第10期12卷 2298-2312页

作者： Hujun WANG Yue TANG Haonan QIU Jingyang HU Yuan SU Jing ZHENG zhongrong zhou Tribology Research Institute School of Mechanical Engineering and Key Laboratory of Advanced Technologies of Materials(Ministry of Education)Southwest Jiaotong UniversityChengdu 610031China

Anti-wear performance of human enamel in the mouth is closely related to the lubrication of salivary *** is well known that the inorganic hydroxyapatite(HA)of the enamel plays an important role in the adsorption and pellicle-forming of salivary proteins on the enamel,but the role of enamel matrix proteins remains *** this study,the adsorption and lubrication behavior of salivary proteins on original,heated,and deproteinated enamel surfaces was comparatively investigated using an atomic force microscopy and nano-indentation/scratch *** with that on the original enamel surface,the adsorption and lubrication behavior of salivary proteins remains almost unchanged on the heated enamel surface(where the enamel matrix proteins are denatured but the size of HA crystalline nanoparticles keeps constant)but exhibits an obvious compromise on the deproteinated enamel surface(where the enamel matrix proteins are removed and agglomeration of HA crystallites occurs).The HA agglomeration weakens the electrostatic interaction of enamel surfaces with salivary proteins to cause a distinct negative influence on the adsorption and pellicle-forming of salivary ***,the negative effect is confirmed with a quartz crystal microbalance with *** summary,by regulating enamel nanostructure for appropriate electrostatic interactions between salivary proteins and enamel surfaces,the enamel matrix proteins play an essential role in the adsorption and pellicle-forming of salivary proteins on human enamel,and then contribute to saliva lubrication,which provides the enamel with an anti-wear *** findings will promote and assist the design of enamel-inspired anti-wear materials.

关键词： enamel matrix proteins hydroxyapatite(HA)crystalline nanoparticles salivary proteins adsorption lubrication

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Investigation of reciprocating friction characteristics between different bionic surfaces of prosthesis materials and skin

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Biosurface and Biotribology 2019年第2期5卷 57-66页

作者： Quanping Feng Wei Li Xidong Liu Wei Ji zhongrong zhou Tribology Research Institution Key Laboratory for Advanced Technology of Materials of Ministry of EducationSouthwest Jiaotong UniversityCheng Du 610031People’s Republic of China Sichuan Bayi Rehabilitation Center(Sichuan Rehabilitation Hospital) Chengdu 611135People’s Republic of China

In this study,three types of bionic texture surfaces were designed,based on the microstructure of tree frog and gecko feet,for two typical prosthetic substrates:silicone rubber and thermoplastic polyurethane elastomer(TPU).The surface energy of all bionic texture surfaces,and the relative displacement and energy dissipation of the reciprocating friction between these bionic surfaces and skin,were *** results revealed that the bionic texture of the prosthetic socket surface had an obvious influence on the surface characteristics and reciprocating characteristics of friction with the *** to the comprehensive weight rating method,the optimal bionic textures for the silicone rubber substrate were a regular hexagonal prism and a quadrangular prism;for the TPU substrate,only the regular quadrangular prism texture was *** textures can effectively increase the surface energy of the surface of the prosthetic socket,thereby increasing its adhesion to skin and reducing the dissipation of friction energy when it interacts with the *** bionic prosthetic socket surface design helps improve the adaptation between the prosthetic socket and the stump.

关键词： socket friction characteristics

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