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Flexural Performance of Steel-FRP Composites for Automotive Applications

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Automotive Innovation 2020年第3期3卷 280-295页

作者： Ye Lin Junying Min Hao Teng Jianping Lin Jiahao Hu NanjieXu School of Mechanical Engineering Tongji UniversityShanghai 201804China key lab of vehicle aerodynamics and vehicle thermal management systems of shanghai Tongji UniversityShanghai 201804China

The design of hybrid structure offers an attractive solution to enhance strength and structural stiffness as well as to achieve lightweight effect and cost reduction.The applications of steel-FRP(fiber-reinforced polymer)composites in trans-portation and civil engineering have been comprehensively reviewed.In order to apply hybrid structures to car body parts such as B-pillar,flexural performance of steel-FRP composites is investigated by means of three-point bending test in this study.An analytical model is deduced to calculate the initial stiffness,the bending load and the energy absorption of steel-FRP composites.Steel-CFRP(carbon fiber-reinforced polymer)and steel-AFRP(aramid fiber-reinforced polymer)composites are experimentally studied and discussed.The results demonstrate that the steel-FRP composites exhibit significantly higher load-carrying capabilities and initial stiffnesses along with larger energy absorptions in the bending process compared to the single steel sheet.

关键词： Steel-FRPcomposite Hybridstructure Fiber-reinforcedpolymer Flexuralperformance

Effect of Atmospheric Pressure Plasma Treatment on the Lap-Shear Strength of Adhesive-Bonded Sheet Molding Compound Joints

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Automotive Innovation 2018年第3期1卷 237-246页

作者： Shuang Wang Junying Min Jianping Lin Chengcheng Sun Shanglu Yang School of Mechanical Engineering Tongji UniversityShanghai 201804China key lab of vehicle aerodynamics and vehicle thermal management systems of shanghai Tongji UniversityShanghai 201804China shanghai Institute of Optics and Fine Mechanics Shanghai 201800China

Atmospheric pressure plasma treatment(APPT)technology was used herein to treat sheet molding compound(SMC)substrates to increase the lap-shear strength of adhesive-bondedSMCjoints.Further,the mechanisms behind the lap-shear strength improvements in APPT-treated adhesive-bonded SMC joints were explored.A maximum lap-shear strength about three times that of the as-received SMC joints was achieved when the APPT distance was set to 20 mm.The surface roughness,which exhibited little benefit to the lap-shear strength,was determined to not be the primary reason for the increase in lap-shear strength.Specifically,X-ray photoelectron spectra revealed that an increased amount of O-containing groups(i.e.,C–O–H,C–O–C,H–O–C=O or R–O–C=O)following APPT contributed to the improved lap-shear strength.In addition,the surface free energy increased significantly after APPT,which improved the lap-shear strength of the adhesive-bonded SMC joints.Compared to the change of surface morphology,the changes in both the surface chemical property and surface free energy played larger roles in increasing the lap-shear strength of APPT-treated SMC joints.

关键词： Plasma treatment Sheet molding compound Lap-shear strength Chemical properties Surface free energies

Axisymmetric Powell-Eyring fluid flow with convective boundary condition: optimal analysis

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Applied Mathematics and Mechanics(English Edition) 2016年第7期37卷 919-928页

作者： T.HAYAT S.MAKHDOOM M.AWAIS S.SALEEM M.M.RASHIDI Department of Mathematics Quaid-i-Azam University Department of Mathematics COMSATS Institute of Information Technology Department of Mathematics Statistics and Physics Qatar University shanghai key lab of vehicle aerodynamics and vehicle thermal management systems Tongji University

The effects of axisymmetric flow of a Powell-Eyring fluid over an impermeable radially stretching surface are presented. Characteristics of the heat transfer process are analyzed with a more realistic condition named the convective boundary condition. Governing equations for the flow problem are derived by the boundary layer approximations. The modeled highly coupled partial differential system is converted into a system of ordinary differential equations with acceptable similarity transformations. The convergent series solutions for the resulting system are constructed and analyzed. Optimal values are obtained and presented in a numerical form using an optimal homotopy analysis method （OHAM）. The rheological characteristics of different parameters of the velocity and temperature profiles are presented graphically. Tabular variations of the skin friction coefficient and the Nusselt number are also calculated. It is observed that the temperature distribution shows opposite behavior for Prandtl and Biot numbers. Furthermore, the rate of heating/cooling is higher for both the Prandtl and Biot numbers.

关键词： axisymmetric flow optimal homotopy analysis method （OHAM） analysis,convective boundary condition

Numerical simulation of flow past a square cylinder with a circular bar upstream and a splitter plate downstream

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Journal of Hydrodynamics 2019年第5期31卷 949-964页

作者： Yuan Ma MMRashidi Zhi-gang Yang shanghai Automotive Wind Tunnel Center Tongji UniversityShanghai 201804China shanghai key laboratory of vehicle aerodynamics and vehicle thermal management systems Shanghai 201804China Department o f Civil Engineering School of EngineeringUniversity of BirminghamBirminghamUK

A numerical investigation of flow past a square cylinder with a circular bar upstream and a splitter plate downstream is carried out in this paper by lattice Boltzmann method(LBM).The combination of the three obstacles and LBM is the main novelty of the present study.The flow patterns are analyzed by a uniform flow of Reynolds number 100 based on the side length of the square cylinder,D.Numerical simulations are performed in the range of 1≤Ds/D≤5,0≤G/D≤7 and 1≤L/D≤6,where Ds,G and L are the center-to center distance,surface-to-surface distance and the splitter plate length,respectively.Six flow patterns are observed in the present study.The maximum percentage reduction in mean drag coefficient is 68.76%at(ds,g,l)=(2.5,0,3)which is in pattern VI.The vortex shedding from the square cylinder and the circular bar can be completely suppressed in pattern VI.The small distance between the square cylinder and the splitter plate plays a more vital role in suppression of vortex shedding as compared with large distance and length.

关键词： Square cylinder lattice Boltzmann method(LBM) reduction of drag forces vortex shedding control circular bar splitter plate

A Critical Review of Real Gas Effects on the Regenerative Refrigerators

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Journal of thermal Science 2021年第3期30卷 782-806页

作者： CAO Qiang LUAN Mingkai LI Peng WEI Li WU Yan Institute of Refrigeration and Cryogenics School of Mechanical EngineeringTongji UniversityShanghai 201804China shanghai key laboratory of vehicle aerodynamics and vehicle thermal management systems Tongji UniversityShanghai 201804China Department of Electrical Engineering School of Electronics and Information EngineeringTongji UniversityShanghai 201804China

The regenerative refrigeration is an important reverse work-heat conversion cycle with a theoretical coefficient of performance(COP)identical to the Carnot efficiency.Practical regenerative refrigerators are capable of working down to 4 K and largely fulfill the refrigeration requirement of modern technologies in many fields,especially for space applications.However,the enthalpy flow associated with the pressure dependence,abbreviated as pressure-induced enthalpy flow,brought about by real gas effects degrades the theoretical COP of the refrigerator to below about 30% of the Carnot efficiency at the temperatures of below the critical point.This paper reviews the long history of exploring the real gas effects which dates back to the 1970 s and continues to now.Important explorations of uncovering the loss mechanism and reducing such losses are summarized.The theories that are in accordance with experimental results and simulation results are expounded.We further carry out analyses on the expansion components,including the pulse tube and the clearance gap.Several inferences are made in order to explore the long-lasting puzzles about real gas effects.It is emphasized that the underlying cause of the loss in the regenerator is an indirect effect of the real gas properties.Further study about carrying out a direct verification of the theory is proposed.

关键词： real gas effects regenerative refrigerators loss mechanism reduction methods

Multi-soliton fusion phenomenon of Burgers equation and fission, fusion phenomenon of Sharma-Tasso-Olver equation

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Journal of Ocean Engineering and Science 2017年第2期2卷 120-126页

作者： Harun Or-Roshid M.M.Rashidi Department of Mathematics Pabna University of Science and TechnologyPabna 6600Bangladesh shanghai key lab of vehicle aerodynamics and vehicle thermal management systems Tongji University4800 Cao An Rd.JiadingShanghai 201804China ENN-Tongji Clean Energy Institute of Advanced Studies China

A direct rational exponential scheme is proposed to construct exact multi-soliton solutions and its fission,fusion phenomena after interaction of the solitons has been discussed.We have considered the Burgers and Sharma-Tasso-Olver equation as two concrete examples to show the fission and fusion of the solitary wave and the solitons,respectively.We improve different structured multi-soliton solutions with possible conditions for fission and fusion of the Burgers and the Sharma-Tasso-Olver equations arises in plasma physics and in ocean dynamics.The amplitude and velocity relations between solitons and/or solitary waves before and after interactions are given and a possible condition for fission and fusion is proposed.Furthermore,three-dimensional plots of the wave solutions are given to visualize the dynamics of the model.©2017 shanghai Jiaotong University.Published by Elsevier B.V.

关键词： Direct rational exponential scheme Burger equation Sharma-Tasso-Olver equation Traveling wave solutions Multi-soliton

Investigation on Precooling Effects of 4 K Stirling-Type Pulse Tube Cryocoolers

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Journal of thermal Science 2019年第4期28卷 714-726页

作者： CAO Qiang LI Zimu LUAN Mingkai SUN Zheng TANG Xiao LI Peng JIANG Zhenhua WEI Li Institute of Refrigeration and Cryogenics School of Mechanical EngineeringTongji UniversityShanghai 201804China shanghai key laboratory of vehicle aerodynamics and vehicle thermal management systems Tongji UniversityShanghai 201804China shanghai Institute of Technical Physics Chinese Academy of SciencesShanghai 200083China Department of Electrical Engineering School of Electronics and Information EngineeringTongji UniversityShanghai 201804China

Stirling-type pulse tube cryocoolers(SPTCs)working at liquid-helium temperatures are appealing in space applications because of their promising advantages such as high reliability,compactness,etc.Worldwide efforts have been put in to develop SPTCs operating at liquid-helium temperatures especially with helium-4 as the working fluid.Staged structure is essential to reach such low temperatures.Generally,both the regenerator of the last section and the pulse tube together with the phase shifter are precooled by its upper stage or by external cold source to a low temperature of around 20 K.However,the precooling effects on the regenerator and the pulse tube are synthetic in previous studies,and their independent effects have not been studied clearly.In this manuscript,the precooling effects on the regenerator and on the pulse tube together with the phase shifter are tested independently on a unique-designed precooled SPTC.The tested precooling temperature is between 13.3 K and 22 K,and the no-load refrigeration temperature gets down to 3.6 K.Further analyses and numerical calculations have been carried out.It is found that the influence on the regenerator is remarkable,which is different from previous conclusions.It is also found that the precooling effects on the pulse tube are relatively weak because of the large pressure-induced enthalpy flow of a real gas working at the temperatures near to the critical point.Furthermore,the phase shifting capacity is analyzed with two cases and with both helium-4 and helium-3 as working fluids,and it keeps quite constant after optimizing the frequency and the precooling temperature for each case.The investigation on these independent effects will provide valid reference on the precooling mechanism study of SPTCs working down to liquid-helium temperatures.

关键词： stirling-type pulse tube cryocooler precooling effects liquid-helium temperatures

A study of heat and mass transfer on magnetohydrodynamic(MHD)flow of nanoparticles

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Propulsion and Power Research 2018年第1期7卷 72-77页

作者： Syed Tauseef Mohyud-Din Umar Khan Naveed Ahmed Muhammad Mehdi Rashidi Department of Mathematics Faculty of SciencesHITEC UniversityTaxila CanttPakistan shanghai key lab of vehicle aerodynamics and vehicle thermal management systems Tongji UniversityShanghai 201804China Center for Research(CFR) University of Islamabad(UoI)IslamabadPakistan Department of Mathematics COMSATS Institute of Information TechnologyAbbottabadPakistan

Investigation of the flow,heat and mass transfer of a nanofluid over a suddenly moved flat plate is presented using Buongiorno's model.This study is different from some of the previous studies as the effects of Brownian motion and thermophoresis on nanoparticles volume fraction are passively controlled on the boundary rather than actively.The partial differential equations governing the flow are reduced to a system of nonlinear ordinary differential equations.Viable similarity transforms are used for this purpose.A well-known numerical scheme called Runge-Kutta-Fehlberg method coupled with shooting procedure has been used to find the solution of resulting system of equations.Discussions on the effects of different emerging parameters is provided using graphical aid.A table is also given that provides the results of different parameters on local Nusselt and Sherwood numbers.The passive control model can be used to control the boundary layer thickness as well as the rate of mass transfer at the wall.

关键词： Nanofluid Brownian motion Thermophoresis Nusselt number Sherwood number

Study of heat and mass transfer with Joule heating on magnetohydrodynamic(MHD)peristaltic blood flow under the influence of Hall effect

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Propulsion and Power Research 2017年第3期6卷 177-185页

作者： M.M.Bhatti M.M.Rashidi shanghai Institute of Applied Mathematics and Mechanics Shanghai UniversityShanghai 200072China shanghai key lab of vehicle aerodynamics and vehicle thermal management systems Tongji UniversityShanghai 201804China ENN-Tongji Clean Energy Institute of Advanced Studies Shanghai 200072China

In this article,heat and mass transfer with Joule heating on magnetohydrodynamic(MHD)peristaltic blood under the influence of Hall effect is examined.Mathematical modelling is based on momentum,energy and concentration which are taken into account using ohms law.The governing partial differential equations are further simplified by neglecting the inertial forces and long wavelength approximations.Exact solutions have been presented for velocity,temperature and concentration profile.The influence of all the physical pertinent parameters is taken into account with the help graphs.It is found that Hartmann number and Hall parameter shows opposite behaviour on velocity,temperature and concentration profile.It is worth mentioning that pressure rise also depicts opposite behaviour for Hartmann number and Hall parameter.The present analysis is also presented for Newtonian fluid(α→0)as a special case for our study.It is observed that Hall Effect and magnetic field shows opposite behaviour on velocity and temperature profile.Temperature profile increases due to the increment in Prandtl number and Eckert number.Numerical comparison is also presented between the existing published results by takingα=0;M=0 as a special case of our study.

关键词： Heat and mass transfer Joule heating Ohms law Blood flow Ree–Eyring fluid