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Biotribology of artificial hip joints

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World Journal of Orthopedics 2015年第1期6卷 77-94页

作者： Francesca Di Puccio Lorenza Mattei Department of civil and industrial engineering University of Pisa

Hip arthroplasty can be considered one of the major successes of orthopedic surgery, with more than 350000 replacements performed every year in the United States with a constantly increasing rate. The main limitations to the lifespan of these devices are due to tribological aspects, in particular the wear of mating surfaces, which implies a loss of matter and modification of surface geometry. However, wear is a complex phenomenon, also involving lubrication and friction. The present paper deals with the tribological performance of hip implants and is organized in to three main sections. Firstly, the basic elements of tribology are presented, from contact mechanics of ball-in-socket joints to ultra high molecular weight polyethylene wear laws. Some fundamental equations are also reported, with the aim of providingthe reader with some simple tools for tribological investigations. In the second section, the focus moves to artificial hip joints, defining materials and geometrical properties and discussing their friction, lubrication and wear characteristics. In particular, the features of different couplings, from metal-on-plastic to metal-on-metal and ceramic-on-ceramic, are discussed as well as the role of the head radius and clearance. How friction, lubrication and wear are interconnected and most of all how they are specific for each loading and kinematic condition is highlighted. Thus, the significant differences in patients and their lifestyles account for the high dispersion of clinical data. Furthermore, such consideration has raised a new discussion on the most suitable in vitro tests for hip implants as simplified gait cycles can be too far from effective implant working conditions. In the third section, the trends of hip implants in the years from 2003 to 2012 provided by the National Joint Registry of England, Wales and Northern Ireland are summarized and commented on in a discussion.

关键词： Arthroplasty Replacement Hip Biotribology Wear Lubrication Friction

Simplified Computation of Reflective Overpressure in Closed Cuboid Space Due to Internal Explosion

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Transactions of Tianjin University 2010年第6期16卷 395-404页

作者：田力李忠献周清 School of civil engineering Tianjin University Binzhou Urban Planning and design Institute

A simplified method is proposed for analyzing the overpressure history of an optional point on the walls of a closed cuboid due to its internal optional point-explosion. Firstly, the overpressure histories of all nodes on the walls of a cube with a side-length of 2 m are computed under a reference-charge explosion at each node of its inner space using the LS-DYNA software, and then are collected to form a reference database. Next, with the thought of the isoparametric finite element, an interpolating algori...

关键词： closed cuboid space reference database reflective overpressure charge weight

The mechanical and water absorption properties of carbon fiber buoyancy materials under hydrostatic pressure

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Science China Technological Sciences 2025年第1期 251-265页

作者： Fanglin CONG Zihan LI Guocai YU Yang JIN Zixu ZHU Linzhi WU College of Aerospace and civil engineering Harbin Engineering University Key Laboratory of Advanced Ship Materials and Mechanics Harbin Engineering University Department of Basic Courses Naval University of Engineering

Buoyancy material technology is of paramount importance for the development of marine engineering. In this study,a novel carbon fiber buoyancy material(CFBM) is designed and prepared by utilizing composite circular tubes with light weight and high strength. To reveal the failure mechanism under hydrostatic pressure, a finite element model(FEM) based on the three-dimensional Hashin and Yeh failure criterion is developed and validated experimentally. Both the simulated and experimental results indicate that the hydrostatic strength of the CFBM is mainly determined by the buckling of carbon fiber tubes located at the edges of the CFBM. Parametric analysis is conducted to investigate the effect of the number of unit-cells,length, and wall thickness of carbon fiber tubes on the mechanical properties of the CFBM. In addition, a 60-day water absorption test of the CFBM at 12.5 MPa is conducted to characterize its durability. Experimental results indicate that the maximum water absorption rate of the CFBM is 0.59% and the hydrostatic strength is reduced by only 7.97% during the 60-day test period. Finally, the designed CFBM is used at the water depth of 1000 m as buoyancy material. Compared with traditional buoyancy materials, the proposed CFBM has significant advantages in both hydrostatic strength and density. This work has broad engineering application prospects and is of high significance for promoting the implementation of carbon fiber composites in the ocean engineering field.

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Ion Transport and Microstructure of Sandwich Cementitious Materials Exposed to Chloride Environment

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Journal of Wuhan University of Technology(Materials Science) 2015年第6期30卷 1274-1278页

作者：王信刚 WANG Kai WANG Rui XIE Tao HUANG Jie School of civil engineering and Architecture Nanchang University School of civil engineering and Architecture East China Jiaotong University Arts and design College Nanchang University

Ion transport of sandwich cementitious materials（SCM） exposed to chloride environment was investigated by accelerated diffusion method and natural diffusion method. Pore structure and micromorphology of SCM were investigated by MIP and SEM-EDS. In comparison with the monolayer structural high performance concrete（HPC）, conductive charge for 6 hours, chloride diffusion coefficient, and apparent chloride diffusion coeffi cient of SCM were decreased by 30%-40%, two orders of magnitude and 40%-50%, respectively. Pore structure of ultra low ion permeability cementitious materials（ULIPCM） prepared for the facesheet is superior to that of HPC prepared for the core. As for porosity, the most probable pore radius, the content of pores with radius 50 nm and the surface area of pores, the order is ULIPCM

关键词： sandwich ion transport pore structure micromorphology

Effects of binder strength and aggregate size on the compressive strength and void ratio of porous concrete

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International Journal of Minerals,Metallurgy and Materials 2009年第6期16卷 714-719页

作者： P. Chindaprasirt S. Hatanaka N. Mishima Y. Yuasa T. Chareerat Department of civil engineering Faculty of Engineering Khon Kaen University Department of Architecture Faculty of Engineering Mie University industrial Research Division Mie Prefecture Science and Technology Promotion Center Department of civil and Environmental engineering Faculty of Science and Engineering Kasetsart University

To test the influence of binder strength, porous concretes with 4 binder strengths between 30.0-135.0 MPa and 5 void ratios between 15%-35% were tested. The results indicated that for the same aggregate, the rates of strength reduction due to the increases in void ratio were the same for binders with different strengths. To study the influence of aggregate size, 3 single size aggregates with nominal sizes of 5.0, 13.0 and 20.0 mm （Nos. 7, 6 and 5 according to JIS A 5001） were used to make porous concrete. The strengths of porous concrete are found to be dependent on aggregate size. The rate of strength reduction of porous concrete with small aggregate size is found to be higher than that with larger aggregate size. At the same void ratio, the strength of porous concrete with large aggregate is larger than that with small aggregate. The general equations for porous concrete are related to compressive strength and void ratio for different binder strengths and aggregate sizes.

关键词： cement paste porous concrete compressive strength void ratio

Structure-preserving properties of three differential schemes for oscillator system

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Applied Mathematics and Mechanics(English Edition) 2014年第6期35卷 783-790页

作者：秦丁越邓子辰胡伟鹏 School of Mechanics Civil Engineering and Architecture NorthwesternPolytechnical University State Key Laboratory of Structural Analysis of industrial Equipment Dalian University of Technology

A numerical method for the Hamiltonian system is required to preserve some structure-preserving properties. The current structure-preserving method satisfies the requirements that a symplectic method can preserve the symplectic structure of a finite dimension Hamiltonian system, and a multi-symplectic method can preserve the multi-symplectic structure of an infinite dimension Hamiltonian system. In this paper, the structure-preserving properties of three differential schemes for an oscillator system are investigated in detail. Both the theoretical results and the numerical results show that the results obtained by the standard forward Euler scheme lost all the three geometric properties of the oscillator system, i.e., periodicity, boundedness, and total energy, the symplectic scheme can preserve the first two geometric properties of the oscillator system, and the St？rmer-Verlet scheme can preserve the three geometric properties of the oscillator system well. In addition, the relative errors for the Hamiltonian function of the symplectic scheme increase with the increase in the step length, suggesting that the symplectic scheme possesses good structure-preserving properties only if the step length is small enough.

关键词： structure-preserving Hamiltonian system Stormer-Verlet method symplectic

Experimental study on microstructural and corrosion behaviors of friction stir processed steel with CoCrFeCuTi HEA reinforcement and effect of annealing

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Science China Technological Sciences 2025年第1期 233-250页

作者： S.Aravind KRISHNA N.RADHIKA Alokesh PRAMANIK N.JEYAPRAKASH Department of Mechanical engineering Amrita School of EngineeringAmrita Vishwa Vidyapeetham School of civil and Mechanical engineering Curtin University School of Mechanical and Electrical engineering China University of Mining and Technology

The ability to perform against extreme corrosion environments in stainless steel depreciates under challenging conditions in industrial applications. This can be resolved by employing surface modification techniques to modify the surface with the required characteristics. The present study investigates the outcomes of friction stir processing of SS304 with CoCrFeCuTi high entropy alloy(HEA) as reinforcement and the property enhancements post-annealing. The synthesized CoCrFeCuTi HEA exhibited irregular fragments with 17 μm mean particle size and body centred cubic(BCC) phase. The microstructure of the processed surface revealed ultra-refined grains with a uniform distribution of HEA filler. The microstructures of the samples annealed at 400℃, 550℃, 700℃ and 850℃ for 2 h also showed significant grain growth and grain refinements. The processed sample with HEA reinforcement annealed at 700℃ exhibited enhanced microhardness and tensile strength by 63% and 0.88 times than that of the processed sample with HEA pre-annealing. The subsequent electrochemical corrosion test displayed better corrosion resistance for the HEA-processed and annealed sample. Hot corrosion tests at 900℃ showcased excellent resistance for the HEA processed and annealed samples by 14.92%, 12.75%, and 14.83% against the samples pre-annealed under three different salt mixtures, and the corroded surface was analyzed.

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Fault Identification for Shear-Type Structures Using Low-Frequency Vibration Modes

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Computer Modeling in engineering & Sciences 2024年第3期138卷 2769-2791页

作者： Cuihong Li Qiuwei Yang Xi Peng School of civil engineering Shaoxing UniversityShaoxing312000China School of civil and Transportation engineering Ningbo University of TechnologyNingbo315211China engineering Research Center of industrial Construction in civil engineering of Zhejiang Ningbo University of TechnologyNingbo315211China

Shear-type structures are common structural forms in industrial and civil buildings,such as concrete and steel frame *** diagnosis of shear-type structures is an important topic to ensure the normal use of *** main drawback of existing damage assessment methods is that they require accurate structural finite element models for damage ***,for many shear-type structures,it is difficult to obtain accurate *** order to avoid finite elementmodeling,amodel-freemethod for diagnosing shear structure defects is developed in this *** method only needs to measure a few low-order vibration modes of the *** proposed defect diagnosis method is divided into two *** the first stage,the location of defects in the structure is determined based on the difference between the virtual displacements derived from the dynamic flexibility matrices before and after *** the second stage,damage severity is evaluated based on an improved frequency sensitivity *** innovations of this method lie in two *** first innovation is the development of a virtual displacement difference method for determining the location of damage in the shear *** second is to improve the existing frequency sensitivity equation to calculate the damage degree without constructing the finite *** has been verified on a numerical example of a 22-story shear frame structure and an experimental example of a three-story steel shear *** on numerical analysis and experimental data validation,it is shown that this method only needs to use the low-order modes of structural vibration to diagnose the defect location and damage degree,and does not require finite element *** proposed method should be a very simple and practical defect diagnosis technique in engineering practice.

关键词： Fault diagnosis shear steel structure vibration mode dynamic flexibility frequency sensitivity

Nonlinear identification of electro-magnetic force model

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Journal of Zhejiang University-Science A(Applied Physics & engineering) 2010年第3期11卷 165-174页

作者： R. SHABANI S. TARIVERDILO H. SALARIEH Mechanical engineering Department Faculty of EngineeringUrmia University civil engineering Department Faculty of EngineeringUrmia University Center of Excellence in design Roboticsand Automation (CEDRA)Sharif University of Technology

Conventional attractive magnetic force models (proportional to the coil current squared and inversely proportional to the gap squared) cannot simulate the nonlinear responses of magnetic bearings in the presence of electromagnetic losses,flux leakage or saturation of *** this paper,based on results from an experimental set-up designed to study magnetic force,a novel parametric model is presented in the form of a nonlinear polynomial with unknown *** parameters of the proposed model are identified using the weighted residual *** of the model identified were performed by comparing the results in time and frequency *** results show a good correlation between experiments and numerical simulations.

关键词： Identification Nonlinear vibration Magnetic bearing Weighted residual method