The interfacial reaction behavior of Al and Ti_(3)AlC_(2)at different pouring temperatures and its effect on the microstructure and mechanical properties of the composites were investigated.The results show that the a...The interfacial reaction behavior of Al and Ti_(3)AlC_(2)at different pouring temperatures and its effect on the microstructure and mechanical properties of the composites were investigated.The results show that the addition of3.0 wt.%Ti_(3)AlC_(2)refines the average grain size ofα(Al)in the composite by 50.1%compared to Al6061 alloy.Morphological analyses indicate that an in-situ Al_(3Ti)transition layer of-180 nm in thickness is generated around the edge of Ti_(3)AlC_(2)at 720℃,forming a well-bonded Al-Al_(3Ti)interface.At this processing temperature,the ultimate tensile strength of A16061-3.0 wt.%Ti_(3)AlC_(2)composite is 199.2 MPa,an improvement of 41.5%over the Al6061 matrix.Mechanism analyses further elucidate that 720℃is favourable for forming the nano-sized transition layer at the Ti_(3)AlC_(2)edges.And,the thermal mismatch strengthening plays a dominant role in this state,with a strengthening contribution of about 74.8%.展开更多
A cohesive zone model is employed to simulate the fiber/matrix interface damage of composites with ductile matrix. The study is carried out to investigate the dependence of the interface damage and the composite tensi...A cohesive zone model is employed to simulate the fiber/matrix interface damage of composites with ductile matrix. The study is carried out to investigate the dependence of the interface damage and the composite tensile strength on the micro parameters of the composite. These parameters contain fiber packing pattern, fiber volume fraction, and the modulus ratio of the fiber to the matrix. The investigation reveals that though the high fiber vo lume fraction, the high fiber′s modulus and the square fiber packing can supply strong reinforcement to the composite, the interface damage is susceptible in these cases. The tensile strength of the composite is dominated by the interface strength when the interface debonding occurs.展开更多
Present work reports chemically reacting Darcy-Forchheimer flow of nanotubes.Water is utilized as base liquid while carbon nanotubes are considered nanomaterial.An exponential stretchable curved surface flow is origin...Present work reports chemically reacting Darcy-Forchheimer flow of nanotubes.Water is utilized as base liquid while carbon nanotubes are considered nanomaterial.An exponential stretchable curved surface flow is originated.Heat source is present.Xue relation of nanoliquid is employed to explore the feature of CNTs (single and multi-wall).Transformation technique is adopted in order to achieve non-linear ordinary differential systems.The governing systems are solved numerically.Effects of involved parameters on flow,temperature,concentration,heat transfer rate (Nusselt number) with addition of skin friction coefficient are illustrated graphically.Decay in velocity is noted with an increment in Forchheimer number and porosity parameter while opposite impact is seen for temperature.Moreover,role of MWCNTs is prominent when compared with SWCNTs.展开更多
This article gives a numerical report to two dimensional(2D)Darcy-Forchheimer flow of carbon-water nanofluid.Flow is instigated by exponential extending curved surface.Viscous liquid in permeable space is described by...This article gives a numerical report to two dimensional(2D)Darcy-Forchheimer flow of carbon-water nanofluid.Flow is instigated by exponential extending curved surface.Viscous liquid in permeable space is described by Darcy-Forchheimer.The subsequent arrangement of partial differential equations is changed into ordinary differential framework through proper transformations.Numerical arrangements of governing frameworks are set up by NDSolve procedure.Outcomes of different sundry parameters on temperature and velocity are examined.Skin friction and heat transfer rate are also shown and inspected.展开更多
Severe surface roughening during plastic deforming of aluminum alloy parts can produce ＂orange peel＂ defects. To analyze ＂orange peel＂ of 6063 aluminum alloy tube quantificationally, the tensile tests of trapezoid...Severe surface roughening during plastic deforming of aluminum alloy parts can produce ＂orange peel＂ defects. To analyze ＂orange peel＂ of 6063 aluminum alloy tube quantificationally, the tensile tests of trapezoidal specimens were carried out. The tubes with different grain sizes were obtained by spinning and subsequent annealing heat treatment. The macroscopical behavior of surface roughening was characterized by surface roughness Ra using a laser scanning confocal microscope. The corresponding microscopic behavior was reflected by microstructures of specimens and in-situ observation using electron back-scattered diffraction（EBSD）. The obtained results show that the surface roughness increased firstly with increasing strain and then decreased slightly. There was a critical strain for aluminum alloy tube, below which ＂orange peel＂ defect would not occur. For the tube with a mean grain size of 80, 105, 130 and 175 μm, the critical strains were 10.17%, 5.74%, 3.15% and 1.62%, respectively. Meanwhile, the surface roughening behavior was produced by serious inhomogeneous deformation between grains as strain increased, and was aggravated as the grain size increased due to the larger local deformation in larger grains.展开更多
The shear behavior of rock joints is important in solving practical problems of rock mechanics. Three group rock joints with different morphologies are made by cement mortar material and a series of CNL(constant norma...The shear behavior of rock joints is important in solving practical problems of rock mechanics. Three group rock joints with different morphologies are made by cement mortar material and a series of CNL(constant normal loading) shear tests are performed. The influences of the applied normal stress and joint morphology to its shear strength are analyzed. According to the experimental results, the peak dilatancy angle of rock joint decreases with increasing normal stress, but increases with increasing roughness. The shear strength increases with the increasing normal stress and the roughness of rock joint. It is observed that the modes of failure of asperities are tensile, pure shear, or a combination of both. It is suggested that the three-dimensional roughness parameters and the tensile strength are the appropriate parameter for describing the shear strength criterion. A new peak shear criterion is proposed which can be used to predict peak shear strength of rock joints. All the used parameters can be easily obtained by performing tests.展开更多
基金financially supported by the National Natural Science Foundation of China(No.51965040)Science and Technology Project of Jiangxi Provincial Department of Transportation,China(No.2022H0048)。
文摘The interfacial reaction behavior of Al and Ti_(3)AlC_(2)at different pouring temperatures and its effect on the microstructure and mechanical properties of the composites were investigated.The results show that the addition of3.0 wt.%Ti_(3)AlC_(2)refines the average grain size ofα(Al)in the composite by 50.1%compared to Al6061 alloy.Morphological analyses indicate that an in-situ Al_(3Ti)transition layer of-180 nm in thickness is generated around the edge of Ti_(3)AlC_(2)at 720℃,forming a well-bonded Al-Al_(3Ti)interface.At this processing temperature,the ultimate tensile strength of A16061-3.0 wt.%Ti_(3)AlC_(2)composite is 199.2 MPa,an improvement of 41.5%over the Al6061 matrix.Mechanism analyses further elucidate that 720℃is favourable for forming the nano-sized transition layer at the Ti_(3)AlC_(2)edges.And,the thermal mismatch strengthening plays a dominant role in this state,with a strengthening contribution of about 74.8%.
文摘A cohesive zone model is employed to simulate the fiber/matrix interface damage of composites with ductile matrix. The study is carried out to investigate the dependence of the interface damage and the composite tensile strength on the micro parameters of the composite. These parameters contain fiber packing pattern, fiber volume fraction, and the modulus ratio of the fiber to the matrix. The investigation reveals that though the high fiber vo lume fraction, the high fiber′s modulus and the square fiber packing can supply strong reinforcement to the composite, the interface damage is susceptible in these cases. The tensile strength of the composite is dominated by the interface strength when the interface debonding occurs.
文摘Present work reports chemically reacting Darcy-Forchheimer flow of nanotubes.Water is utilized as base liquid while carbon nanotubes are considered nanomaterial.An exponential stretchable curved surface flow is originated.Heat source is present.Xue relation of nanoliquid is employed to explore the feature of CNTs (single and multi-wall).Transformation technique is adopted in order to achieve non-linear ordinary differential systems.The governing systems are solved numerically.Effects of involved parameters on flow,temperature,concentration,heat transfer rate (Nusselt number) with addition of skin friction coefficient are illustrated graphically.Decay in velocity is noted with an increment in Forchheimer number and porosity parameter while opposite impact is seen for temperature.Moreover,role of MWCNTs is prominent when compared with SWCNTs.
文摘This article gives a numerical report to two dimensional(2D)Darcy-Forchheimer flow of carbon-water nanofluid.Flow is instigated by exponential extending curved surface.Viscous liquid in permeable space is described by Darcy-Forchheimer.The subsequent arrangement of partial differential equations is changed into ordinary differential framework through proper transformations.Numerical arrangements of governing frameworks are set up by NDSolve procedure.Outcomes of different sundry parameters on temperature and velocity are examined.Skin friction and heat transfer rate are also shown and inspected.
基金Project(IRT1229)supported by Program for Chang-jiang Scholars and Innovative Research Team in University,China
文摘Severe surface roughening during plastic deforming of aluminum alloy parts can produce ＂orange peel＂ defects. To analyze ＂orange peel＂ of 6063 aluminum alloy tube quantificationally, the tensile tests of trapezoidal specimens were carried out. The tubes with different grain sizes were obtained by spinning and subsequent annealing heat treatment. The macroscopical behavior of surface roughening was characterized by surface roughness Ra using a laser scanning confocal microscope. The corresponding microscopic behavior was reflected by microstructures of specimens and in-situ observation using electron back-scattered diffraction（EBSD）. The obtained results show that the surface roughness increased firstly with increasing strain and then decreased slightly. There was a critical strain for aluminum alloy tube, below which ＂orange peel＂ defect would not occur. For the tube with a mean grain size of 80, 105, 130 and 175 μm, the critical strains were 10.17%, 5.74%, 3.15% and 1.62%, respectively. Meanwhile, the surface roughening behavior was produced by serious inhomogeneous deformation between grains as strain increased, and was aggravated as the grain size increased due to the larger local deformation in larger grains.
基金Project(41130742)supported by the Key Program of National Natural Science Foundation of ChinaProject(2014CB046904)supportedby the National Basic Research Program of China+1 种基金Project(2011CDA119)supported by Natural Science Foundation of Hubei Province,ChinaProject(40972178)supported by the General Program of National Natural Science Foundation of China
文摘The shear behavior of rock joints is important in solving practical problems of rock mechanics. Three group rock joints with different morphologies are made by cement mortar material and a series of CNL(constant normal loading) shear tests are performed. The influences of the applied normal stress and joint morphology to its shear strength are analyzed. According to the experimental results, the peak dilatancy angle of rock joint decreases with increasing normal stress, but increases with increasing roughness. The shear strength increases with the increasing normal stress and the roughness of rock joint. It is observed that the modes of failure of asperities are tensile, pure shear, or a combination of both. It is suggested that the three-dimensional roughness parameters and the tensile strength are the appropriate parameter for describing the shear strength criterion. A new peak shear criterion is proposed which can be used to predict peak shear strength of rock joints. All the used parameters can be easily obtained by performing tests.
