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Damping of aluminum-matrix composite reinforced by carbon nanotube:Multiscale modeling and characteristics

Science China(Technological Sciences) 2023年第4期66卷 1062-1074页

作者： WANG Fei LI Li TANG HaiShan WANG XueLin HU YuJin State Key Laboratory of Digital Manufacturing Equipment and Technology School of Mechanical Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China

It is a crucial requirement for structure-damping materials to attain both stiffness and damping;unfortunately,the two properties are usually mutually exclusive.This study interestingly demonstrates that introducing Ni atoms into the interface of carbon nanotube(CNT)reinforced aluminum-matrix composites can defeat the conflict of stiffness versus damping.This originates from the gradient variation of the modulus and energy dissipation in the effective interfacial zone.The rule of mixture is modified by taking the interface contribution into account,and a gradient damping model is proposed to account for the contribution of the interface energy dissipation.Molecular dynamics simulations confirm that the proposed multiscale modulus and damping models can describe the elastic modulus and damping behavior of the composites with different volume fractions and different diameters of CNTS.The gradient interface slip caused by the lattice mismatches and misfit dislocations between Ni-coated CNT and aluminum is one of the pathways for achieving unprecedented levels of the product of stiffness and damping.

关键词： molecular dynamics interfacial dissipation elastic modulus damping loss modulus

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Effect of ammonium based ionic liquids on the rheological behavior of the heavy crude oil for high pressure and high temperature conditions

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Petroleum 2022年第4期8卷 552-566页

作者： Sivabalan Sakthivel Sugirtha Velusamy Center for Integrative Petroleum Research(CIPR) College of Petroleum Engineering&GeosciencesKing Fahd University of Petroleum&MineralsDhahran31261Saudi Arabia Petroleum Engineering Program Department of Ocean EngineeringIndian Institute of Technology MadrasChennai600036India

Heavy crude oil(HCO)production,processing,and transportation forms several practical challenges to the oil and gas industry,due to its higher viscosity.Understanding the shear rheology of this HCO is highly important to tackle production and flow assurance.The environmental and economic viability of the conventional methods(thermal or dilution with organic solvents),force the industry to find an alternative.The present study was constructed to investigate the effect of eco-friendly ionic liquids(ILs)on the HCO's rheology,at high temperature and high pressure.Eight different alkyl ammonium ILs were screened for HCO's shear rheology at the temperatures of 25-100℃ and for pressures 0.1e10 MPa.The addition of ILs reduced the HCO's viscosity substantially from 25 to 33%from their original HCO viscosity.Also,it aids to reduce the yield stress to about 15-20%at all the studied experimental conditions.Furthermore,the viscoelastic property of the HCO was studied for both strain-sweep and frequencysweep and noticed the ILs helps to increase HCO's loss modulus(G00)by reducing storage modulus(G0),it leads to the reduction of the crossover point around 25-32%than the standard HCO.Mean the ILs addition with HCO converts its solid-like nature into liquid-like material.Besides,the effect ILs chain length was also studied and found the ILs which has lengthier chain length shows better efficiency on the flow-ability.Finally,the microscopic investigation of the HCO sample was analyzed with and without ILs and witnessed that these ILs help to fragment the flocculated HCO into smaller fractions.These findings indicate that the ILs could be considered as the better alternative for efficient oil production,processing,and transportation.

关键词： Crude oil Ionic liquids loss modulus Microscopy Storage modulus Viscosity reduction

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Strain Amplitude Effect on the Viscoelastic Mechanics of Chloroprene Rubber

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Acta Mechanica Solida Sinica 2020年第3期33卷 392-402页

作者： Longfan Peng Zhida Li Yunyu Li Institute of Transportation Wuhan University of TechnologyWuhan 430063HubeiChina

This paper establishes an empirical formula to predict the strain amplitude effect.A viscoelastic constitutive model-the superposition of a hyperelastic model and a viscoelastic model-is constructed based on the laws of thermodynamics.The Mooney Rivlin model and the Prony series are employed for uniaxial tension testing.The empirical formula is derived using a hysteresis loop;it obtains results that are in agreement with the experimental results of dynamic mechanical analysis(DMA).The empirical formula proposed in this paper has certain accuracy in predicting the dynamic modulus under different strain amplitudes.

关键词： Viscoelasticity Strain amplitude effect Storage modulus loss modulus Hysteresis loop

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Reinforcing Effect of Organo-Modified Fillers in Rubber Composites as Evidenced from DMA Studies

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材料科学与工程（中英文A版） 2022年第1期12卷 13-23页

作者： Raji Vijay A.R.Ravindranatha Menon National Institute for Interdisciplinary Science&Technology Council of Scientific and Industrial ResearchThiruvananthapuram 695019KeralaIndia

The use of organically enhanced kaolin clay as reinforcing filler for NR(natural rubber)and blends of NR with NBR(nitrile-butadiene rubber)and poly BR(butadiene rubber)system were investigated on the basis of DMA(dynamic mechanical analysis).Kaolin clay was modified using a chemical complex of HH(hydrazine hydrate)and SRSO(sodium salt of rubber seed oil).Intercalation of SRSO into kaolin under optimized condition showed an inter-lamellar layer expansion to 4.668 nm,compared to the characteristic d001 XRD(X-ray diffraction)peak of pristine kaolin at 0.714 nm.The morphology,visco-elastic behavior,modulus property,polymer miscibility and Tg(glass transition temperature)of nano-kaolin filled NR and its blend with synthetic rubbers have been studied in detail.DMA showed a diminution in tanδpeak height and a modulus shift in correspondence with increased CLD(crosslink density).Pure NR shows only~1%increase in storage modulus(E′)while adding nanoclay rather than micron sized pristine clay under experimental conditions,because of the feeble interaction between filler and matrix,as compared to blend.An increment of~76%and~117%in E′was recognized by the addition of 4 wt%nanoclay in blends such as BR mK and NBR mK.With loss modulus(E″)pure NR shows only~7%decrease while adding nanoclay,compared to blend.A decrement of~54%and~55%in E″by the addition of 4 wt%nanoclay in BR mK and NBR mK blends were observed.As a whole,DMA was performed to figure out the effect of surface modification enabling to materialize composite.

关键词： Reinforcement rubber cross link density storage modulus loss modulus damping factor surface modification

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Simulation of viscoelastic behavior of defected rock by using numerical manifold method

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Frontiers of Structural and Civil Engineering 2011年第2期5卷 199-207页

作者： Feng REN Lifeng FAN Guowei MA School of Civil and Environmental Engineering Nanyang Technological UniversitySingapore 639798Singapore School of Civil and Resource Engineering The University of Western AustraliaCrawleyWA 6009Australia

Numerical simulations of longitudinal wave propagation in a rock bar with microcracks are conducted by using the numerical manifold method which has great advantages in the simulation of discontinuities.Firstly,validation of the numerical manifold method is carried out by simulations of a longitudinal stress wave propagating through intact and cracked rock bars.The behavior of the stress wave traveling in a one-dimensional rock bar with randomly distributed microcracks is subsequently studied.It is revealed that the highly defected rock bar has significant viscoelasticity to the stress wave propagation.Wave attenuation as well as time delay is affected by the length,quantity,specific stiffness of the distributed microcracks as well as the incident stress wave frequency.The storage and loss moduli of the defected rock are also affected by the microcrack properties;however,they are independent of incident stress wave frequency.

关键词： stress wave propagation defected rock numerical manifold method viscoelastic behavior storage modulus loss modulus

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Viscoelastic rheological property of different types of polymer solutions for enhanced oil recovery

Viscoelastic rheological property of different types of poly...

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The 9th National Conference on Rheology

作者：孟令伟康万利周阳王志伟刘述忍白宝君 Enhanced Oil Recovery Research Center China University of Pe~oleum Enhanced Oil Recovery Research Center China University of Petroleum Missouri University of Science and Technology

The capability of hydrophobic association polymer(HAPAM)to displace oil is different from that of hydrolyzed polyacrylamide(HPAM)because they have different theological properties.The viscoelasticity of five polymers was measured using Physica MCR301 rheometer and was compared.The five polymers include three HAPAMs with relative molecular mass of 1 248×10(Type Ⅰ),750×10(Type Ⅱ),and 571×10(Type Ⅲ)separately and two HPAMs with relative molecular mass of 1 200×10 and 3 800×10 respectively.The experiment results indicate that the viscoelasticity of HAPAM is better than that of HPAM.The storage modulus G′and the loss modulus G″for HAPAM solutions are also larger than those for HPAM.Comparing the theological curves of different HAPAM types,it is found that the viscosity of type Ⅱ and type Ⅲ is almost same at different shear rates while the viscosity of type Ⅰ is the lower than that of Types Ⅱ and Ⅲ.The storage modulus G′and the loss modulus G″for three types of HAPAM were measured in low oscillation frequency range,and the results show that G′is greater than G″for all three different types of HAPAM,but their loss modulus is almost same,and the G′is in the order of type Ⅱ>type Ⅲ>type Ⅰ.In addition,the G′and G″increase with aging time for all three HAPAM solutions were stayed at different days.The viscoelasticity of type Ⅰ reaches the highest value when aging time is 9 d at 45℃,but it is 7 d for type Ⅱ and type Ⅲ. The different viscoelasticity properties can be attributed to self-organization supermolecule networks which is formed by hydrophobic association of HAPAM molecular and molecular chain entanglement.

关键词： hydrophobic association polymer rheology storage modulus loss modulus self-organization aggregate

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