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A dissipated energy comparison to evaluate fatigue resistance using 2-point bending

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Journal of Traffic and Transportation Engineering(English Edition) 2014年第1期1卷 49-54页

作者： Cinzia Maggiore Gordon Airey Paul Marsac NTEC University of NottinghamNottinghamUnited Kingdom IFSTTAR NantesFrance

Fatigue is the main failure mode in pavement engineering. Typically, micro-cracks originate at the bottom of asphalt concrete layer due to horizontal tensile strains. Micro-cracks start to propagate towards the upper layers under repeated loading which can lead to pavement failure. Different methods are usually used to describe fatigue behavior in asphalt materials such as： phenomenological approach, fracture mechanics approach and dissipated energy ap- proach. This paper presents a comparison of fatigue resistances calculated for different dissipated energy models using 2-point bending （2PB） at IFSTTAR in Nantes. 2PB tests have been undertaken under different loading and environmental conditions in order to evaluate the properties of the mixtures （stiffness, dissipated energy, fatigue life and healing effect）.

关键词： fatigue resistance dissipated energy 2-point bending fracture mechanics approach

Tribological behavior and energy dissipation characteristics of nano-Al_2O_3-reinforced PTFE-PPS composites in sliding system

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Journal of Central South University 2017年第9期24卷 2001-2009页

作者：曹文翰龚俊杨东亚高贵王宏刚任俊芳陈生圣 School of Mechanical and Electrical Engineering Lanzhou University of Technology State Key Laboratory of Solid lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of Sciences

Nanoparticles are increasingly being used to improve the friction and wear performance of polymers. In this study, we investigated the tribological behavior and energy dissipation characteristics of nano-Al_2O_3-reinforced polytetrafluoroethylenepolyphenylene sulfide(PTFE-PPS) composites in a sliding system. The tribological behaviors of the composites were evaluated under different normal loads(100–300 N) at a high linear velocity(2 m/s) using a block-on-ring tester. Addition of the nano-Al_2O_3 filler improved the antiwear performance of the PTFE-PPS composites, and the friction coefficient increased slightly. The lowest wear rate was obtained when the nano-Al_2O_3 content was 3%(volume fraction). Further, the results indicated a linear correlation between wear and the amount of energy dissipated, even though the wear mechanism changed with the nano-Al_2O_3 content, independent of the normal load applied.

关键词： nano-Al2O3 polytetrafluoroethylene-polyphenylene sulfide (PTFE-PPS) tribological behavior dissipated energy

Study on the energy evolution mechanism of low-temperature concrete under uniaxial compression

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Research in Cold and Arid Regions 2022年第3期14卷 162-172页

作者： QinYong Ma Kweku Darko Forson School of Civil Engineering and Architecture Anhui University of Science and TechnologyHuainanAnhui 232001China Engineering Research Center of Underground Mine Construction Ministry of EducationAnhui University of Science and TechnologyHuainanAnhui 232001China

In order to study the mechanical properties and energy evolution of low-temperature concrete during uniaxial compres‐sion, a uniaxial compression test was performed on concrete. In addition, the evolution laws of compressive strength, deformation modulus and total energy, elastic potential energy, dissipated energy and peak energy of concrete in the process of deformation and failure are analyzed. The effects of age and temperature on low-temperature concrete is analyzed from the perspective of energy. Test results show that temperature improves the strength and deformation of concrete to varying degrees. When cured for 28 days, the compressive strength and deformation modulus of concrete at −20 ℃ is increased by 17.98% and 21.45% respectively, compared with the compressive strength and deformation modulus at room temperature of 20 ℃. At the point of failure of the concrete under uniaxial compression, the total damage energy and the dissipation energy both increase, while the developed elastic strain energy increases and then decreases. Increase in curing duration tends to increase the total destruction energy of concrete, peak point elastic strain energy, peak point dissipation energy, and peak point total energy. Whereas increase in curing durations, has shown to decrease the total destruction energy of concrete, the peak point elastic strain energy, peak point dissipation energy, and peak point total energy. The peak point strain energy reflects the ability of low-temperature concrete to reasonably resist damage. By using the principle of energy analysis to study the deformation process of concrete, it provides research methods and ideas for the deformation analysis of this type of material under load.

关键词： low-temperature concrete uniaxial compression mechanical properties energy mechanism dissipated energy

Stability analysis of an aeroelastic system with friction

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Chinese Journal of Aeronautics 2013年第3期26卷 624-630页

作者： Tan Tiancai Li Min Liu Baihui School of Aeronautic Science and Engineering Beihang University

In this paper, harmonic balance method, exact formulation and numerical simulation method are adopted to study the effects of different friction stiffness on the stability of 1.5 degrees of freedom aeroelastic system. On this basis, the expressions of input energy and dissipated energy are deduced, and the energy method is used to reveal the mechanisms of the stable boundary and unstable boundary existing in the system and the effects of different friction stiffness on the stability of the system. Studies have shown that the stability region and the critical aerodynamic damping ratio of the system rise with the increase of the friction stiffness, while the friction stiffness has little effect on the stability boundary. In the analysis of the stability of system, the results of harmonic balance method, exact formulation and Newmark of numerical simulation method are in good agreement. Compared with exact formulation and numerical simulation method, the concept and conclusion of harmonic balance method are simple in the system stability analysis.

关键词： Critical aerodynamic damping dissipated energy Hysteresis spring friction Input energy Stability

A Novel Hybrid Clustering Based Transmission Protocol for Wireless Body Area Networks

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Computers, Materials & Continua 2021年第11期69卷 2459-2473页

作者： Neelam Sharma Harshita Chadha Karan Singh B.M.Singh Nitish Pathak Research Scholar Computer Science and EngineeringUttarakhand Technical University(UTU)DehradunIndia Computer Science and Engineering Maharaja Agrasen Institute of TechnologyNew DelhiIndia School of Computer&Systems Sciences Jawaharlal Nehru University(JNU)DelhiIndia College of Engineering Roorkee UTUDehradunIndia Department of Information Technology KIET Group of InstitutionsGhaziabadIndia

Wireless sensor networks are a collection of intelligent sensor devices that are connected to one another and have the capability to exchange information packets amongst *** recent years,this field of research has become increasingly popular due to the host of useful applications it can potentially serve.A deep analysis of the concepts associated with this domain reveals that the two main problems that are to be tackled here are throughput enhancement and network security *** present article takes on one of these two issues namely the throughput *** the purpose of improving network productivity,a hybrid clustering based packet propagation protocol has been *** protocol makes use of not only clustering mechanisms of machine learning but also utilizes the traditional forwarding function approach to arrive at an optimum *** result of the simulation is a novel transmission protocol which significantly enhances network productivity and increases throughput value.

关键词： Forwarding function wireless sensor networks WSNs WBANs energy characteristics clustering hybrid mechanism dissipated energy network stability

Assessment of cyclic deformation and critical stress amplitude of jointed rocks via cyclic triaxial testing

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Journal of Rock Mechanics and Geotechnical Engineering 2023年第6期15卷 1370-1390页

作者： Waranga Habaraduwa Peellage Behzad Fatahi Haleh Rasekh School of Civil and Environmental Engineering University of Technology SydneySydneyAustralia

Jointed rock specimens with a natural replicated joint surface oriented at a mean dip angle of 60were prepared,and a series of cyclic triaxial tests was performed at different confining pressures and cyclic deviatoric stress *** samples were subjected to 10,000 loading-unloading cycles with a frequency of 8 *** each level of confining pressure,the applied cyclic deviatoric stress amplitude was increased incrementally until excessive deformation of the jointed rock specimen was *** of the test results indicated that there existed a critical cyclic deviatoric stress amplitude(*** dynamic deviatoric stress)beyond which the jointed rock specimens *** measured critical dynamic deviatoric stress was less than the corresponding static deviatoric *** cyclic deviatoric stress amplitudes less than the critical dynamic deviatoric stress,minor cumulative residual axial strains were observed,resulting in hysteretic ***,for cyclic deviatoric stresses beyond the critical dynamic deviatoric stress,the plastic strains increased promptly,and the resilient moduli degraded rapidly during the initial loading *** triaxial test results showed that at higher confining pressures,the ultimate residual axial strain attained by the jointed rock specimen decreased,the steadystate dissipated energy density and steady-state damping ratio per load cycle decreased,while steadystate resilient moduli increased.

关键词： Cyclic triaxial test Jointed rock Joint surface Confining pressure Cyclic deviatoric stress amplitude Failure Residual deformation dissipated energy

Investigation on Fatigue Model of Asphalt Concrete Containing Conductive Fillers

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武汉理工大学学报 2010年第17期32卷 62-66页

作者： LI W T WU S P ZHU Z H LIU Z F Key Laboratory of Silicate Materials Science and Engineering Wuhan University of TechnologyWuhan 430070China

The snow and ice on asphalt pavement are very dangerous to people,automobiles and airplanes,so melting snow and ice becomes a high profile. Investigation on the asphalt concrete containing conductive fillers has a great contribution to the researches of melting snow and ice. However,it is few to research on the fatigue behavior which is important in the profile. By four-point bending fatigue tests,the specific fatigue models of conductive asphalt concrete were developed. The parameters of three fatigue models were regressed,the three models predicted the fatigue behavior by the strain levels,the strain levels and initial mix stiffness and dissipated energy respectively. In the model of the strain levels,the fatigue life is decreased at the same strain level as the conductive filler is added. The model based on the strain levels and initial mix stiffness reveals that the fatigue life is partly affected by the initial mix stiffness which is influenced by the conductive filler. The model used the dissipated energy approach is adopted to predict the fatigue behavior with the introduction of the impact the conductive filler on the dissipated energy.

关键词： conductive asphalt concrete model fatigue life strain level stiffness dissipated energy

Nosing process of empty and foam-filled circular metal tubes on semispherical die by theoretical and experimental investigations

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Transactions of Nonferrous Metals Society of China 2017年第9期27卷 1976-1988页

作者： Seyed Ghaem AMIRHOSSEINI Abbas NIKNEJAD Nader SETOUDEH Mechanical Engineering Department Yasouj University Materials Engineering Department Yasouj University

Nosing process of circular metal tubes in empty and polyurethane foam-filled conditions on a semispherical rigid die was analyzed by theoretical and experimental methods.A new theoretical model of plastic deformation of circular metal tubes was demonstrated during the nosing process on a rigid semispherical *** on the analytical model,some theoretical relations were calculated to estimate instantaneous forming load and dissipated energy of empty and foam-filled circular metal tubes versus axial *** circular brazen and aluminum tubes were prepared and shaped into semispherical nosed nozzles to verify the present *** of theoretical predictions and the corresponding experimental measurements reveals that predicted load?displacement and dissipated energy?displacement diagrams by theoretical formulas have a good correlation with the corresponding experimental curves and it proves verity of the ***,the present theory shows that dissipated energy and axial load of empty tubes depend on material type,wall thickness and diameter of the tubes and they are independent of tube initial ***,the experimental results show that the presence of polyethylene Teflon-constraints increases ultimate axial displacement of the forming process.

关键词： plastic deformation nosing process dissipated energy circular tube nozzle axial load axial displacement