Three types of Al/Al−27%Si laminated composites,each containing 22%Si,were fabricated via hot pressing and hot rolling.The microstructures,mechanical properties and thermo-physical properties of these composites were ...Three types of Al/Al−27%Si laminated composites,each containing 22%Si,were fabricated via hot pressing and hot rolling.The microstructures,mechanical properties and thermo-physical properties of these composites were investigated.The results demonstrated that the three laminated composites exhibited similar microstructural features,characterized by well-bonded interfaces between the Al layer and the Al−27%Si alloy layer.The tensile and flexural strengths of the composites were significantly higher than those of both Al−22%Si and Al−27%Si alloys.These strengths increased gradually with decreasing the layer thickness,reaching peak values of 222.5 and 407.4 MPa,respectively.Crack deflection was observed in the cross-sections of the bending fracture surfaces,which contributed to the enhanced strength and toughness.In terms of thermo-physical properties,the thermal conductivity of the composites was lower than that of Al−22%Si and Al−27%Si alloys.The minimum reductions in thermal conductivity were 6.8%and 0.9%for the T3 laminated composite,respectively.Additionally,the coefficient of thermal expansion of the composites was improved,exhibiting varying temperature-dependent behaviors.展开更多
Plasma electrolytic oxidation(PEO)coatings were prepared on Al−Mg laminated macro composites(LMCs)using both unipolar and bipolar waveforms in an appropriate electrolyte for both aluminum and magnesium alloys.The tech...Plasma electrolytic oxidation(PEO)coatings were prepared on Al−Mg laminated macro composites(LMCs)using both unipolar and bipolar waveforms in an appropriate electrolyte for both aluminum and magnesium alloys.The techniques of FESEM/EDS,grazing incident beam X-ray diffraction(GIXRD),and electrochemical methods of potentiodynamic polarization and electrochemical impedance spectroscopy(EIS)were used to characterize the coatings.The results revealed that the coatings produced using the bipolar waveform exhibited lower porosity and higher thickness than those produced using the unipolar one.The corrosion performance of the specimens’cut edge was investigated using EIS after 1,8,and 12 h of immersion in a 3.5 wt.%NaCl solution.It was observed that the coating produced using the bipolar waveform demonstrated the highest corrosion resistance after 12 h of immersion,with an estimated corrosion resistance of 5.64 kΩ·cm^(2),which was approximately 3 times higher than that of the unipolar coating.Notably,no signs of galvanic corrosion were observed in the LMCs,and only minor corrosion attacks were observed on the magnesium layer in some areas.展开更多
This study aims to investigate the propagation of harmonic waves in nonlocal magneto-electro-elastic(MEE)laminated composites with interface stress imperfections using an analytical approach.The pseudo-Stroh formulati...This study aims to investigate the propagation of harmonic waves in nonlocal magneto-electro-elastic(MEE)laminated composites with interface stress imperfections using an analytical approach.The pseudo-Stroh formulation and nonlocal theory proposed by Eringen were adopted to derive the propagator matrix for each layer.Both the propagator and interface matrices were formulated to determine the recursive fields.Subsequently,the dispersion equation was obtained by imposing traction-free and magneto-electric circuit open boundary conditions on the top and bottom surfaces of the plate.Dispersion curves,mode shapes,and natural frequencies were calculated for sandwich plates composed of BaTiO3 and CoFe2O4.Numerical simulations revealed that both interface stress and the nonlocal effect influenced the tuning of the dispersion curve and mode shape for the given layup.The nonlocal effect caused a significant decrease in the dispersion curves,particularly in the high-frequency regions.Additionally,compared to the nonlocal effect,the interface stress exerted a greater influence on the mode shapes.The generalized analytical framework developed in this study provides an effective tool for both the theoretical analysis and practical design of MEE composite laminates.展开更多
In Ti-Al laminated composites,cracks nucleate preferentially at the Al_(3)Ti layer,but the inhibitory effect of Al_(3)Ti on crack extension is ignored.Interestingly,by combining experiment and phase-field crystal simu...In Ti-Al laminated composites,cracks nucleate preferentially at the Al_(3)Ti layer,but the inhibitory effect of Al_(3)Ti on crack extension is ignored.Interestingly,by combining experiment and phase-field crystal simulation,we found that the micrometer Al_(3)Ti particles in the diffusion layer play the role of crack deflection and passivation,which is attributed to the lattice distortion induced by Al_(3)Ti consumes the energy of the crack in extension.In addition,it is found that the growth process of Al_(3)Ti is divided into two stages:nucleation stage and growth stage.Compared with the growth stage,the Al_(3)Ti grains in the nucleation stage are finer in the growth layer.Finer grains show better crack deflection and avoid stress concentration.展开更多
The remarkable mechanical properties exhibited by laminated structures have generated significant in-terest in the realm of additively manufactured laminated high-entropy alloys(HEAs).Despite this bur-geoning interest...The remarkable mechanical properties exhibited by laminated structures have generated significant in-terest in the realm of additively manufactured laminated high-entropy alloys(HEAs).Despite this bur-geoning interest,the nexus between process,structure,and properties within laminated HEAs remains largely uncharted.There is a vast space for investigating the effect of the typical heterogeneous interface on the macroscopic mechanical properties.This study focuses on the influence of the characteristic het-erogeneous interface on macroscopic mechanical properties of laminated HEAs,particularly anisotropy.Using the 3D-printed Fe_(50)Mn_(30)Co_(10)Cr_(10)-CoCrNi HEA as a model,we investigate the impact of interface geometry on mechanical characteristics.Tensile tests show that the reduced interface spacing increases yield strength.This laminated HEA displays significant anisotropy in strength and ductility,depending on the loading direction relative to the interface.Electron microscopic observations suggest that finer layer spacing enhances interface and dislocation strengthening,increasing yield strength.Anisotropic behaviors are confirmed to be mediated by interface orientation,explained in terms of deformation compatibility and crack development at the interface.This research offers fundamental insights into the relationship between heterogeneous interfaces and the mechanical properties in laminated HEAs.The knowledge is vital for designing,fabricating,and optimizing laminated HEAs through additive manufacturing,advancing their engineering applications.展开更多
Al/Cu laminate composite was fabricated based on hot press sintering using Cu sheet and Al powders as raw materials.The effects of sintering parameters on interfacial structure and mechanical properties were investiga...Al/Cu laminate composite was fabricated based on hot press sintering using Cu sheet and Al powders as raw materials.The effects of sintering parameters on interfacial structure and mechanical properties were investigated.The results revealed that a uniform Al/Cu interface with excellent bonding quality was achieved.The thickness of intermetallic compounds(IMCs)reached 33.88μm after sintering at 620℃for 2 h,whereas it was only 14.88μm when sintered at 600℃for 1 h.AlCu phase was developed through the reaction between Al4Cu9 and Al2Cu with prolonging sintering time,and an amorphous oxide strip formed at AlCu/Al4Cu9 interface.Both the grain morphology and interfacial structure affected the tensile strength of Al/Cu laminate,whereas the mode of tensile fracture strongly relied on the interfacial bonding strength.The highest tensile strength of 151.1 MPa and bonding strength of 93.7 MPa were achieved after sintering at 600℃for 1 h.展开更多
The Cu/1010 steel bimetal laminated composites(BLCs)were rolled to different thicknesses to investigate the effect of rolling direction and reduction on the microstructure evolution and mechanical properties.The diffe...The Cu/1010 steel bimetal laminated composites(BLCs)were rolled to different thicknesses to investigate the effect of rolling direction and reduction on the microstructure evolution and mechanical properties.The difference of mechanical properties between the Cu and 1010 steel causes different thickness reductions,percentage spread,and cladding ratios.The formation of strong texture induces larger strength of the rolled samples,and as the volume fraction of 1010 steel is larger in Route-A,its strength is consistently greater than that in Route-B.The obstruction of interface to crystal and dislocation slip results in the formation of interface distortion,inducing dislocation density gradient when the rolling reduction is low in Route-A.The slip planes of the Cu and 1010 steel are more prone to suffer the normal strain,while the shear strain of other crystal planes is obviously larger than the normal strain under rolling load near the interface.展开更多
Copper matrix composites prepared via traditional methods face mechanical property and electrical conductivity trade-off problems.In this study,TiB_(2)/Cu−Cu heterogeneous laminated composites with submicron lamellar ...Copper matrix composites prepared via traditional methods face mechanical property and electrical conductivity trade-off problems.In this study,TiB_(2)/Cu−Cu heterogeneous laminated composites with submicron lamellar thicknesses were prepared via flake powder metallurgy(FPM)using gas-atomized in situ composite powders as raw material.By thermal mismatch strengthening,and the geometrically necessary dislocations(GNDs)generated by mechanically incompatible deformation between adjacent heterogeneous lamellae and their interaction with statistically stored dislocations(SSDs),the as-prepared TiB_(2)/Cu−Cu submicron laminated composites(SLCs)exhibit significantly enhanced mechanical properties.At the same time,the interaction and propagation of multimode cracks provide extrinsic toughening for SLCs.The pure Cu lamellae with low density grain boundaries and dislocations and no TiB_(2)particles provide a channel with little electron scattering for the rapid transport of carriers,thereby ensuring high electrical conductivity.展开更多
Longitudinal seismic performance is a critical aspect to be considered during the tunnel design process,in addition to cross-sectional considerations.The present study proposed using a laminated shear energy dissipati...Longitudinal seismic performance is a critical aspect to be considered during the tunnel design process,in addition to cross-sectional considerations.The present study proposed using a laminated shear energy dissipation(LSED)structure to achieve effective longitudinal seismic design.The proposed structure consists of thin steel plates and alternately bonded layers of rubber,which can be installed around the periphery of the secondary lining.This configuration guarantees that the tunnels will exhibit optimal axial deformation capacity and robust rigid resistance to circumferential compression from the surrounding rock.To evaluate the impact of the LSED structure on the longitudinal seismic performance of the tunnel,a fine numerical model of the LSED structureetunnel liningesurrounding rock system was developed using finite element simulation.The evaluation criteria include maximum principal stress and strain energy.The seismic response of the tunnel with the LSED structure exhibited a notable reduction of over 40%in terms of seismic attenuation rate when subjected to the Trinidad seismic wave compared to the tunnel without the LSED structure.Furthermore,the aseismic mechanism of the proposed LSED structure is discussed,considering both internal factors such as the rubber shear modulus,steel plate dimensions,and number and location of structures,and external influencing factors such as seismic wave parameters and surrounding rock quality.Meanwhile,the effectiveness of the tunnel with the LSED structure has been quantitatively demonstrated in terms of seismic fragility curves.展开更多
The development of geological lamination in shale reservoirs influences fracture propagation during hydraulic stimulation,and the fracture generation mechanism as it propagates through the laminated interface is close...The development of geological lamination in shale reservoirs influences fracture propagation during hydraulic stimulation,and the fracture generation mechanism as it propagates through the laminated interface is closely related to fracturing effects.In this paper,the laminated shale was selected to conduct three-point bending experiments using digital image correlation(DIC)and acoustic emission(AE)techniques,which revealed that the propagation path of cross-layer fractures exhibits dislocation features.The cohesive fracture mechanism of cross-layer fractures is investigated from the viewpoint of the fracture process zone(FPZ),which displays the characteristics of intermittence and dislocation during fracture development.A computational criterion for predicting the dislocation of cross-layer fracture at the interface is proposed,which shows that the maximum dislocation range does not exceed 72%of the FPZ length.Considering the mechanical differences between adjacent layers of laminated shale,the cohesive zone model of cross-layer fracture is discussed,from which the constitutive relationship and fracture energy during FPZ development are characterized,and the discontinuous nature of the constitutive relationship is found.This study improves the understanding of the geometry and cohesive fracture mechanism of the cross-layer fracture and provides valuable insights for field fracturing in shale reservoirs.展开更多
1060/7050 Al/Al laminated metal composites(LMCs)with heterogeneous lamellar structures were prepared by accumulative roll bonding(ARB),cold rolling and subsequent annealing treatment.The strengthening mechanism was in...1060/7050 Al/Al laminated metal composites(LMCs)with heterogeneous lamellar structures were prepared by accumulative roll bonding(ARB),cold rolling and subsequent annealing treatment.The strengthening mechanism was investigated by microstructural characterization,mechanical property tests and in-situ fracture morphology observations.The results show that microstructural differences between the constituent layers are present in the Al/Al LMCs after various numbers of ARB cycles.Compared with rolled 2560-layered Al/Al LMCs with 37.5%and 50.0%rolling reductions,those with 62.5%rolling reductions allow for more effective improvements in the mechanical properties after annealing treatment due to their relatively high mechanical incompatibility across the interface.During tensile deformation,with the increased magnitude of incompatibility in the 2560-layered Al/Al LMC with a heterogeneous lamellar structure,the densities of the geometrically necessary dislocations(GNDs)increase to accommodate the relatively large strain gradient,resulting in considerable back stress strengthening and improved mechanical properties.展开更多
The bonding interface of 7B52 Al alloy laminated composite （ALC） fabricated by hot rolling was investigated using optical microscopy （OM）, transmission electron microscopy （TEM）, scanning electron microscopy （...The bonding interface of 7B52 Al alloy laminated composite （ALC） fabricated by hot rolling was investigated using optical microscopy （OM）, transmission electron microscopy （TEM）, scanning electron microscopy （SEM）, ultrasonic flaw detection （UFD）, and bonding strength tests. The results show that metallurgical bonding is achieved at the interface after composite rolling. The TEM analysis and tensile tests indicate that the 7B52 ALC plate combines high strength of the hard individual layer and good toughness of the soft individual layer. However, UFD technology and SEM analysis prove that the defects （thick oxide films, acid washed residues, air, oil and coarse particles） existing in the bonding interface are harmful to the bonding strength. To sum up, the composite roiling process is suitable for 7B52 ALC plate, and the content and size of the defects should be controlled strictly. Advanced surface treatment of each individual layer would be beneficial to further improve the bonding quality.展开更多
The microstructural development and its effect on the mechanical properties of Al/Cu laminated composite produced by asymmetrical roll bonding and annealing were studied. The composite characterizations were conducted...The microstructural development and its effect on the mechanical properties of Al/Cu laminated composite produced by asymmetrical roll bonding and annealing were studied. The composite characterizations were conducted by transmission electron microscope（TEM）, scanning electron microscope（SEM）, peeling tests and tensile tests. It is found that the ultra-fine grained laminated composites with tight bonding interface are prepared by the roll bonding technique. The annealing prompts the atomic diffusion in the interface between dissimilar matrixes, and even causes the formation of intermetallic compounds. The interfacial bonding strength increases to the maximum value owing to the interfacial solution strengthening at 300 °C annealing, but sharply decreases by the damage effect of intermetallic compounds at elevated temperatures. The composites obtain high tensile strength due to the Al crystallization grains and Cu twins at 300 °C. At 350 °C annealing, however, the composites get high elongation by the interfacial interlayer with submicron thickness.展开更多
To meet the demands for large space and flexible compartmentation ofbuildings, laminated vierendeel trasses are adopted in high-position transfer story structures.First the bearing characteristics are analyzed, in whi...To meet the demands for large space and flexible compartmentation ofbuildings, laminated vierendeel trasses are adopted in high-position transfer story structures.First the bearing characteristics are analyzed, in which reasonable stiffness ratio of the upperchord, middle chord, and lower chord is derived. Then combined with an actual engineering model (1:8similar ratio), the static loading and pseudo-dynamic tests of two models for laminated vierendeeltrass used in transfer story structures are conducted, in which one model adopts reinforcedconcrete, and the other adopts prestressed concrete and shape steel concrete. Seismic behaviors areanalyzed, including inter-story displacement, base shear-displacement skeleton curves, andequivalent viscosity-damping curves. A program is programmed to carry out the elasto-plastic dynamicanalysis, and displacement time-history curves of the two models are derived. The test and analysisresults show that the laminated vierendeel trass with prestressed concrete and shape steel concretehas excellent seismic behaviors. It can solve the disadvantages of laminated vierendeel trussesused in transfer story structures. Finally, some design suggestions are put forward, which can bereferenced by similar engineering.展开更多
Surface notches lower the stiffness of laminated strips, so they lower the buckling loads of the laminated strips, too. In this paper a new method is proposed to predict the buckling loads of the laminated strips with...Surface notches lower the stiffness of laminated strips, so they lower the buckling loads of the laminated strips, too. In this paper a new method is proposed to predict the buckling loads of the laminated strips with a surface notch. The theoretical and experimental results show that the buckling loads decrease as the depth or width of the surface notches increase; when the stacking sequence of the laminated strips is [0°/0°/+ θ/-θ/0°/0°/+θ/-θ] s , the buckling load decrease as θ increases. It proves that the method is reliable and significant.展开更多
This paper deals with the progressive failure analysis of composite laminates. Triangular elements which include the transverse shear effects are us.d for the stress analysis. A new method for the calculation of the s...This paper deals with the progressive failure analysis of composite laminates. Triangular elements which include the transverse shear effects are us.d for the stress analysis. A new method for the calculation of the shear correction factors is presented. Several failure criteria are used to check the first ply failure and distinguish the laminate failure modes into fiber breakage or buckling, matrix cracking and delamination. After the failure is detected, the stiffness of the failed ply is modified according to the failure modes. The ultimate strength of the laminate is obtained by an iterative way. Several examples are given in the paper for stress analysis and progressive failure analysis of composite laminates.展开更多
Regarding laminated structures,an electromechanically coupled Finite Element(FE)model based on Layerwise Third-Order Shear Deformation(LW-TOSD)theory is proposed for sta-tic and dynamic analysis.LW-TOSD ensures the co...Regarding laminated structures,an electromechanically coupled Finite Element(FE)model based on Layerwise Third-Order Shear Deformation(LW-TOSD)theory is proposed for sta-tic and dynamic analysis.LW-TOSD ensures the continuity of in-plane displacements and trans-verse shear stresses.The current LW-TOSD can be applied to arbitrary multi-layer laminated structures with only seven Degrees of Freedom(DOFs)for each element node and eliminates the use of the shear correction factors.Moreover,a shear penalty stiffness matrix is constructed to sat-isfy artificial constraints to optimize the structural shear strain.A dynamic finite element model is obtained based on LW-TOSD using the Hamilton's principle.First,the accuracy of the current model is validated by comparing with literature and ABAQUS results.Then,this study carries out numerical investigations of piezolaminated structures for different width-to-thickness ratios,length-to-width ratios,penalty stiffness matrix,boundary conditions,electric fields and dynamics.展开更多
Laminated metal composites(LMCs) are a unique composite material and have great application prospects in automobiles, ships, aircraft,and other manufacturing industries. As lightweight materials, the Mg/Al LMCs are ex...Laminated metal composites(LMCs) are a unique composite material and have great application prospects in automobiles, ships, aircraft,and other manufacturing industries. As lightweight materials, the Mg/Al LMCs are expected to combine the advantages of both Mg and Al alloys to broaden their application prospects. Roll-bonding is the most popular process for the fabrication of Mg/Al LMCs due to high production efficiency and good product quality stability. The roll-bonding process involves the deformation of the substrates and the formation of the interfacial diffusion layer. The latter will directly determine the interface bonding strength of Mg/Al LMCs. Bonding strength is very sensitive to the thickness of the reaction layer in the diffusion layer. When the thickness of the reaction layer exceeds 5 μm, the bonding strength decreases sharply. Therefore, controlling the thickness of the reaction layer is very important for the design of rolling parameters.The latest research also showed that the addition of intermediate layer metal and the construction of three-dimensional interfaces can further improve the interface bonding strength. How to apply these methods to roll-bonding is the focus of future research. Recently, a new rolling technique, corrugated roll/plat roll rolling+flat roll/flat roll rolling has been developed to fabricate Mg/Al LMCs. It can effectively promote the deformation of the hard layer and generate a wavy interface, resulting in the enhancement of the bonding quality and rolling quality.In the current review, the effects of rolling parameters and subsequent annealing on the interface structure of Mg/Al LMCs were elaborated in detail. The application of some special rolling techniques in the preparation of Mg/Al LMCs was also summarized. The latest research results on the relationship between interface structure and mechanical properties of Mg/Al LMCs were reviewed. Finally, further research directions in this field were proposed.展开更多
Hetero-structured thermally conductive spherical boron nitride and boron nitride nanosheets(BNN-30@BNNS)fillers were prepared via electro static self-assembly method.And the corresponding thermally conductive&elec...Hetero-structured thermally conductive spherical boron nitride and boron nitride nanosheets(BNN-30@BNNS)fillers were prepared via electro static self-assembly method.And the corresponding thermally conductive&electrically insulating BNN-30@BNNS/Si-GFs/E-44 laminated composites were then fabricated via hot compression.BNN-30@BNNS-Ⅲ(fBNN-30/fBNNS,1/2,wt/wt)fillers presented the optimal synergistic improvement effects on the thermal conductivities of epoxy composites.When the mass fraction of BNN-30@BNNS-Ⅲwas 15 wt%,λvalue of the BNN-30@BNNS-Ⅲ/E-44 composites was up to0.61 W m^(-1)K^(-1),increased by 2.8 times compared with pure E-44(λ=0.22 W m^(-1)K^(-1)),also higher than that of the 15 wt%BNN-30/E-44(0.56 W m^(-1)K^(-1)),15 wt%BNNS/E-44(0.42 W m^(-1)K^(-1)),and 15 wt%(BNN-30/BNNS)/E-44(direct blending BNN-30/BNNS hybrid fillers,1/2,wt/wt,0.49 W m^(-1)K^(-1))composites.Theλin-plane(λ//)andλcross-plane(λ_(⊥))of 15 wt%BNN-30@BNNS-Ⅲ/Si-GFs/E-44 laminated composites significantly reached 2.75 W m^(-1)K^(-1)and 1.32 W m^(-1)K^(-1),186.5%and 187.0%higher than those of Si-GFs/E-44 laminated composites(λ//=0.96 W m^(-1)K^(-1)andλ_(⊥)=0.46 W m^(-1)K^(-1)).Established models can well simulate heat transfer efficiency in the BNN-30@BNNS-Ⅲ/Si-GFs/E-44 laminated composites.Under the condition of point heat source,the introduction of BNN-30@BNNS-Ⅲfillers were conducive to accelerating heat flow trans fe r.BNN-30@BNNS-Ⅲ/Si-GFs/E-44 laminated composites also demonstrated outstanding electrical insulating properties(cross-plane withstanding voltage,breakdown strength,surface&volume resistivity of 51.3 kV,23.8 kV mm^(-1),3.7×10^(14)Ω&3.4×10^(14)Ω·cm,favorable mechanical properties(flexural strength of 401.0 MPa and ILSS of 22.3 MPa),excellent dielectric properties(εof 4.92 and tanδof 0.008)and terrific thermal properties(T_(g)of 167.3℃and T_(HRI)of 199.2℃).展开更多
Analytical studies on the vibration and sound radiation characteristics of an asymmetric laminated rectangular plate are carried out in this paper. Theoretical formulations, in which the effects of thermal environment...Analytical studies on the vibration and sound radiation characteristics of an asymmetric laminated rectangular plate are carried out in this paper. Theoretical formulations, in which the effects of thermal environments are taken into account, are derived for the vibration and sound radiation based on both first-order shear deformation plate theory and Rayleigh integral. It is found that the natural frequencies, the resonant amplitudes of vibration response and the sound pressure level decrease with the temperature rising. The natural frequencies of asym- metric plates are smaller than those of symmetric plates and the velocity responses of asymmetric plates are larger than those of symmetric plates.展开更多
基金supported by the National Natural Science Foundation of China(No.52274369)the National Key Laboratory of Science and Technology on High-strength Structural Materials,China(No.623020034).
文摘Three types of Al/Al−27%Si laminated composites,each containing 22%Si,were fabricated via hot pressing and hot rolling.The microstructures,mechanical properties and thermo-physical properties of these composites were investigated.The results demonstrated that the three laminated composites exhibited similar microstructural features,characterized by well-bonded interfaces between the Al layer and the Al−27%Si alloy layer.The tensile and flexural strengths of the composites were significantly higher than those of both Al−22%Si and Al−27%Si alloys.These strengths increased gradually with decreasing the layer thickness,reaching peak values of 222.5 and 407.4 MPa,respectively.Crack deflection was observed in the cross-sections of the bending fracture surfaces,which contributed to the enhanced strength and toughness.In terms of thermo-physical properties,the thermal conductivity of the composites was lower than that of Al−22%Si and Al−27%Si alloys.The minimum reductions in thermal conductivity were 6.8%and 0.9%for the T3 laminated composite,respectively.Additionally,the coefficient of thermal expansion of the composites was improved,exhibiting varying temperature-dependent behaviors.
文摘Plasma electrolytic oxidation(PEO)coatings were prepared on Al−Mg laminated macro composites(LMCs)using both unipolar and bipolar waveforms in an appropriate electrolyte for both aluminum and magnesium alloys.The techniques of FESEM/EDS,grazing incident beam X-ray diffraction(GIXRD),and electrochemical methods of potentiodynamic polarization and electrochemical impedance spectroscopy(EIS)were used to characterize the coatings.The results revealed that the coatings produced using the bipolar waveform exhibited lower porosity and higher thickness than those produced using the unipolar one.The corrosion performance of the specimens’cut edge was investigated using EIS after 1,8,and 12 h of immersion in a 3.5 wt.%NaCl solution.It was observed that the coating produced using the bipolar waveform demonstrated the highest corrosion resistance after 12 h of immersion,with an estimated corrosion resistance of 5.64 kΩ·cm^(2),which was approximately 3 times higher than that of the unipolar coating.Notably,no signs of galvanic corrosion were observed in the LMCs,and only minor corrosion attacks were observed on the magnesium layer in some areas.
基金supported by the Ministry of Science and Technology Taiwan under Grant No.MOST 109-2628-E-009-002-MY3.
文摘This study aims to investigate the propagation of harmonic waves in nonlocal magneto-electro-elastic(MEE)laminated composites with interface stress imperfections using an analytical approach.The pseudo-Stroh formulation and nonlocal theory proposed by Eringen were adopted to derive the propagator matrix for each layer.Both the propagator and interface matrices were formulated to determine the recursive fields.Subsequently,the dispersion equation was obtained by imposing traction-free and magneto-electric circuit open boundary conditions on the top and bottom surfaces of the plate.Dispersion curves,mode shapes,and natural frequencies were calculated for sandwich plates composed of BaTiO3 and CoFe2O4.Numerical simulations revealed that both interface stress and the nonlocal effect influenced the tuning of the dispersion curve and mode shape for the given layup.The nonlocal effect caused a significant decrease in the dispersion curves,particularly in the high-frequency regions.Additionally,compared to the nonlocal effect,the interface stress exerted a greater influence on the mode shapes.The generalized analytical framework developed in this study provides an effective tool for both the theoretical analysis and practical design of MEE composite laminates.
基金supported by the National Natural Science Foundation of China(Nos.52375394,52074246,52275390,52205429,52201146)the National Defense Basic Scientific Research Program of China(JCKY2020408B002)the Key Research and Development Program of Shanxi Province(202102050201011,202202050201014).
文摘In Ti-Al laminated composites,cracks nucleate preferentially at the Al_(3)Ti layer,but the inhibitory effect of Al_(3)Ti on crack extension is ignored.Interestingly,by combining experiment and phase-field crystal simulation,we found that the micrometer Al_(3)Ti particles in the diffusion layer play the role of crack deflection and passivation,which is attributed to the lattice distortion induced by Al_(3)Ti consumes the energy of the crack in extension.In addition,it is found that the growth process of Al_(3)Ti is divided into two stages:nucleation stage and growth stage.Compared with the growth stage,the Al_(3)Ti grains in the nucleation stage are finer in the growth layer.Finer grains show better crack deflection and avoid stress concentration.
基金supported by the National Natural Science Foundation of China(No.12272392 and 11790292)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB22040303)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(No.2022020).
文摘The remarkable mechanical properties exhibited by laminated structures have generated significant in-terest in the realm of additively manufactured laminated high-entropy alloys(HEAs).Despite this bur-geoning interest,the nexus between process,structure,and properties within laminated HEAs remains largely uncharted.There is a vast space for investigating the effect of the typical heterogeneous interface on the macroscopic mechanical properties.This study focuses on the influence of the characteristic het-erogeneous interface on macroscopic mechanical properties of laminated HEAs,particularly anisotropy.Using the 3D-printed Fe_(50)Mn_(30)Co_(10)Cr_(10)-CoCrNi HEA as a model,we investigate the impact of interface geometry on mechanical characteristics.Tensile tests show that the reduced interface spacing increases yield strength.This laminated HEA displays significant anisotropy in strength and ductility,depending on the loading direction relative to the interface.Electron microscopic observations suggest that finer layer spacing enhances interface and dislocation strengthening,increasing yield strength.Anisotropic behaviors are confirmed to be mediated by interface orientation,explained in terms of deformation compatibility and crack development at the interface.This research offers fundamental insights into the relationship between heterogeneous interfaces and the mechanical properties in laminated HEAs.The knowledge is vital for designing,fabricating,and optimizing laminated HEAs through additive manufacturing,advancing their engineering applications.
基金the financial support from the National Natural Science Foundation of China(Nos.51875317,52222510)Key Research and Development Program of Shandong Province,China(No.2021ZLGX01)。
文摘Al/Cu laminate composite was fabricated based on hot press sintering using Cu sheet and Al powders as raw materials.The effects of sintering parameters on interfacial structure and mechanical properties were investigated.The results revealed that a uniform Al/Cu interface with excellent bonding quality was achieved.The thickness of intermetallic compounds(IMCs)reached 33.88μm after sintering at 620℃for 2 h,whereas it was only 14.88μm when sintered at 600℃for 1 h.AlCu phase was developed through the reaction between Al4Cu9 and Al2Cu with prolonging sintering time,and an amorphous oxide strip formed at AlCu/Al4Cu9 interface.Both the grain morphology and interfacial structure affected the tensile strength of Al/Cu laminate,whereas the mode of tensile fracture strongly relied on the interfacial bonding strength.The highest tensile strength of 151.1 MPa and bonding strength of 93.7 MPa were achieved after sintering at 600℃for 1 h.
基金the National Key Research and Development Program of China(No.2018YFE0306103)the National Natural Science Foundation of China(No.52071050)+1 种基金the Science and Technology Innovation Project of Ningbo,China(No.2021Z032)the Program of China Scholarships Council(No.202106060148).
文摘The Cu/1010 steel bimetal laminated composites(BLCs)were rolled to different thicknesses to investigate the effect of rolling direction and reduction on the microstructure evolution and mechanical properties.The difference of mechanical properties between the Cu and 1010 steel causes different thickness reductions,percentage spread,and cladding ratios.The formation of strong texture induces larger strength of the rolled samples,and as the volume fraction of 1010 steel is larger in Route-A,its strength is consistently greater than that in Route-B.The obstruction of interface to crystal and dislocation slip results in the formation of interface distortion,inducing dislocation density gradient when the rolling reduction is low in Route-A.The slip planes of the Cu and 1010 steel are more prone to suffer the normal strain,while the shear strain of other crystal planes is obviously larger than the normal strain under rolling load near the interface.
基金supported by the National Natural Science Foundation of China(Nos.52127802,52322409,52271137)the Scientific Research Program of Education Department of Shaanxi Province,China(No.22JY050)the Science and Technology Project of Xi’an,China(No.2021SFGX0004).
文摘Copper matrix composites prepared via traditional methods face mechanical property and electrical conductivity trade-off problems.In this study,TiB_(2)/Cu−Cu heterogeneous laminated composites with submicron lamellar thicknesses were prepared via flake powder metallurgy(FPM)using gas-atomized in situ composite powders as raw material.By thermal mismatch strengthening,and the geometrically necessary dislocations(GNDs)generated by mechanically incompatible deformation between adjacent heterogeneous lamellae and their interaction with statistically stored dislocations(SSDs),the as-prepared TiB_(2)/Cu−Cu submicron laminated composites(SLCs)exhibit significantly enhanced mechanical properties.At the same time,the interaction and propagation of multimode cracks provide extrinsic toughening for SLCs.The pure Cu lamellae with low density grain boundaries and dislocations and no TiB_(2)particles provide a channel with little electron scattering for the rapid transport of carriers,thereby ensuring high electrical conductivity.
基金supported by the National Natural Science Foundation of China(Grant No.52109132)the Shandong Provincial Natural Science Foundation(Grant No.ZR2020QE270).
文摘Longitudinal seismic performance is a critical aspect to be considered during the tunnel design process,in addition to cross-sectional considerations.The present study proposed using a laminated shear energy dissipation(LSED)structure to achieve effective longitudinal seismic design.The proposed structure consists of thin steel plates and alternately bonded layers of rubber,which can be installed around the periphery of the secondary lining.This configuration guarantees that the tunnels will exhibit optimal axial deformation capacity and robust rigid resistance to circumferential compression from the surrounding rock.To evaluate the impact of the LSED structure on the longitudinal seismic performance of the tunnel,a fine numerical model of the LSED structureetunnel liningesurrounding rock system was developed using finite element simulation.The evaluation criteria include maximum principal stress and strain energy.The seismic response of the tunnel with the LSED structure exhibited a notable reduction of over 40%in terms of seismic attenuation rate when subjected to the Trinidad seismic wave compared to the tunnel without the LSED structure.Furthermore,the aseismic mechanism of the proposed LSED structure is discussed,considering both internal factors such as the rubber shear modulus,steel plate dimensions,and number and location of structures,and external influencing factors such as seismic wave parameters and surrounding rock quality.Meanwhile,the effectiveness of the tunnel with the LSED structure has been quantitatively demonstrated in terms of seismic fragility curves.
基金financiallysupported by the Excellent Young Fund of Sinopec Petroleum Exploration and Production Research Institute(Grant No.YK2024009)the National Natural Science Foundation of China(Grant Nos.U23B6004 and 51925405).
文摘The development of geological lamination in shale reservoirs influences fracture propagation during hydraulic stimulation,and the fracture generation mechanism as it propagates through the laminated interface is closely related to fracturing effects.In this paper,the laminated shale was selected to conduct three-point bending experiments using digital image correlation(DIC)and acoustic emission(AE)techniques,which revealed that the propagation path of cross-layer fractures exhibits dislocation features.The cohesive fracture mechanism of cross-layer fractures is investigated from the viewpoint of the fracture process zone(FPZ),which displays the characteristics of intermittence and dislocation during fracture development.A computational criterion for predicting the dislocation of cross-layer fracture at the interface is proposed,which shows that the maximum dislocation range does not exceed 72%of the FPZ length.Considering the mechanical differences between adjacent layers of laminated shale,the cohesive zone model of cross-layer fracture is discussed,from which the constitutive relationship and fracture energy during FPZ development are characterized,and the discontinuous nature of the constitutive relationship is found.This study improves the understanding of the geometry and cohesive fracture mechanism of the cross-layer fracture and provides valuable insights for field fracturing in shale reservoirs.
基金financial support from the Special Fund for Special Posts of Guizhou University,China(No.[2022]06)the Guizhou Provincial Basic Research Program(Natural Science),China(No.ZK[2023]78)+1 种基金the National Natural Science Foundation of China(No.52365020)the Open Fund Project of Key Laboratory of Advanced Manufacturing Technology,China(No.GZUAMT2022KF[04]).
文摘1060/7050 Al/Al laminated metal composites(LMCs)with heterogeneous lamellar structures were prepared by accumulative roll bonding(ARB),cold rolling and subsequent annealing treatment.The strengthening mechanism was investigated by microstructural characterization,mechanical property tests and in-situ fracture morphology observations.The results show that microstructural differences between the constituent layers are present in the Al/Al LMCs after various numbers of ARB cycles.Compared with rolled 2560-layered Al/Al LMCs with 37.5%and 50.0%rolling reductions,those with 62.5%rolling reductions allow for more effective improvements in the mechanical properties after annealing treatment due to their relatively high mechanical incompatibility across the interface.During tensile deformation,with the increased magnitude of incompatibility in the 2560-layered Al/Al LMC with a heterogeneous lamellar structure,the densities of the geometrically necessary dislocations(GNDs)increase to accommodate the relatively large strain gradient,resulting in considerable back stress strengthening and improved mechanical properties.
基金Project(51312JQ08)supported by the Pre-Research Foundation of China General Equipment DepartmentProject(NBPJ2013-4)supported by the Postdoctoral Science Foundation of Ningbo Branch of China Academy of Ordnance Science+1 种基金Project(bsh1402073)supported by the Postdoctoral Science Foundation of Zhejiang Province,ChinaProject(2014A610051)supported by the Ningbo Natural Science Foundation of China
文摘The bonding interface of 7B52 Al alloy laminated composite （ALC） fabricated by hot rolling was investigated using optical microscopy （OM）, transmission electron microscopy （TEM）, scanning electron microscopy （SEM）, ultrasonic flaw detection （UFD）, and bonding strength tests. The results show that metallurgical bonding is achieved at the interface after composite rolling. The TEM analysis and tensile tests indicate that the 7B52 ALC plate combines high strength of the hard individual layer and good toughness of the soft individual layer. However, UFD technology and SEM analysis prove that the defects （thick oxide films, acid washed residues, air, oil and coarse particles） existing in the bonding interface are harmful to the bonding strength. To sum up, the composite roiling process is suitable for 7B52 ALC plate, and the content and size of the defects should be controlled strictly. Advanced surface treatment of each individual layer would be beneficial to further improve the bonding quality.
基金Projects(50971038,51174058)supported by the National Natural Science Foundation of China
文摘The microstructural development and its effect on the mechanical properties of Al/Cu laminated composite produced by asymmetrical roll bonding and annealing were studied. The composite characterizations were conducted by transmission electron microscope（TEM）, scanning electron microscope（SEM）, peeling tests and tensile tests. It is found that the ultra-fine grained laminated composites with tight bonding interface are prepared by the roll bonding technique. The annealing prompts the atomic diffusion in the interface between dissimilar matrixes, and even causes the formation of intermetallic compounds. The interfacial bonding strength increases to the maximum value owing to the interfacial solution strengthening at 300 °C annealing, but sharply decreases by the damage effect of intermetallic compounds at elevated temperatures. The composites obtain high tensile strength due to the Al crystallization grains and Cu twins at 300 °C. At 350 °C annealing, however, the composites get high elongation by the interfacial interlayer with submicron thickness.
文摘To meet the demands for large space and flexible compartmentation ofbuildings, laminated vierendeel trasses are adopted in high-position transfer story structures.First the bearing characteristics are analyzed, in which reasonable stiffness ratio of the upperchord, middle chord, and lower chord is derived. Then combined with an actual engineering model (1:8similar ratio), the static loading and pseudo-dynamic tests of two models for laminated vierendeeltrass used in transfer story structures are conducted, in which one model adopts reinforcedconcrete, and the other adopts prestressed concrete and shape steel concrete. Seismic behaviors areanalyzed, including inter-story displacement, base shear-displacement skeleton curves, andequivalent viscosity-damping curves. A program is programmed to carry out the elasto-plastic dynamicanalysis, and displacement time-history curves of the two models are derived. The test and analysisresults show that the laminated vierendeel trass with prestressed concrete and shape steel concretehas excellent seismic behaviors. It can solve the disadvantages of laminated vierendeel trussesused in transfer story structures. Finally, some design suggestions are put forward, which can bereferenced by similar engineering.
文摘Surface notches lower the stiffness of laminated strips, so they lower the buckling loads of the laminated strips, too. In this paper a new method is proposed to predict the buckling loads of the laminated strips with a surface notch. The theoretical and experimental results show that the buckling loads decrease as the depth or width of the surface notches increase; when the stacking sequence of the laminated strips is [0°/0°/+ θ/-θ/0°/0°/+θ/-θ] s , the buckling load decrease as θ increases. It proves that the method is reliable and significant.
文摘This paper deals with the progressive failure analysis of composite laminates. Triangular elements which include the transverse shear effects are us.d for the stress analysis. A new method for the calculation of the shear correction factors is presented. Several failure criteria are used to check the first ply failure and distinguish the laminate failure modes into fiber breakage or buckling, matrix cracking and delamination. After the failure is detected, the stiffness of the failed ply is modified according to the failure modes. The ultimate strength of the laminate is obtained by an iterative way. Several examples are given in the paper for stress analysis and progressive failure analysis of composite laminates.
基金support from the National Natural Science Foundation of China (No.11972020)the Natural Science Foundation of Shanghai,China (No.21ZR1424100).
文摘Regarding laminated structures,an electromechanically coupled Finite Element(FE)model based on Layerwise Third-Order Shear Deformation(LW-TOSD)theory is proposed for sta-tic and dynamic analysis.LW-TOSD ensures the continuity of in-plane displacements and trans-verse shear stresses.The current LW-TOSD can be applied to arbitrary multi-layer laminated structures with only seven Degrees of Freedom(DOFs)for each element node and eliminates the use of the shear correction factors.Moreover,a shear penalty stiffness matrix is constructed to sat-isfy artificial constraints to optimize the structural shear strain.A dynamic finite element model is obtained based on LW-TOSD using the Hamilton's principle.First,the accuracy of the current model is validated by comparing with literature and ABAQUS results.Then,this study carries out numerical investigations of piezolaminated structures for different width-to-thickness ratios,length-to-width ratios,penalty stiffness matrix,boundary conditions,electric fields and dynamics.
基金supported by Guangdong Major Project of Basic and Applied Basic Research,No. 2020B0301030006。
文摘Laminated metal composites(LMCs) are a unique composite material and have great application prospects in automobiles, ships, aircraft,and other manufacturing industries. As lightweight materials, the Mg/Al LMCs are expected to combine the advantages of both Mg and Al alloys to broaden their application prospects. Roll-bonding is the most popular process for the fabrication of Mg/Al LMCs due to high production efficiency and good product quality stability. The roll-bonding process involves the deformation of the substrates and the formation of the interfacial diffusion layer. The latter will directly determine the interface bonding strength of Mg/Al LMCs. Bonding strength is very sensitive to the thickness of the reaction layer in the diffusion layer. When the thickness of the reaction layer exceeds 5 μm, the bonding strength decreases sharply. Therefore, controlling the thickness of the reaction layer is very important for the design of rolling parameters.The latest research also showed that the addition of intermediate layer metal and the construction of three-dimensional interfaces can further improve the interface bonding strength. How to apply these methods to roll-bonding is the focus of future research. Recently, a new rolling technique, corrugated roll/plat roll rolling+flat roll/flat roll rolling has been developed to fabricate Mg/Al LMCs. It can effectively promote the deformation of the hard layer and generate a wavy interface, resulting in the enhancement of the bonding quality and rolling quality.In the current review, the effects of rolling parameters and subsequent annealing on the interface structure of Mg/Al LMCs were elaborated in detail. The application of some special rolling techniques in the preparation of Mg/Al LMCs was also summarized. The latest research results on the relationship between interface structure and mechanical properties of Mg/Al LMCs were reviewed. Finally, further research directions in this field were proposed.
基金support and funding from Guangdong Basic and Applied Basic Research Foundation(2019B1515120093)National Natural Science Foundation of China(51773169 and 51973173)+3 种基金Natural Science Basic Research Plan for Distinguished Young Scholars in Shaanxi Province(2019JC11)Open Fund from Henan University of Science and Technology(2020-RSC02)Foundation for Doctor Dissertation of Northwestern Polytechnical University(CX202055)financially supported by Polymer Electromagnetic Functional Materials Innovation Team of Shaanxi Sanqin Scholars。
文摘Hetero-structured thermally conductive spherical boron nitride and boron nitride nanosheets(BNN-30@BNNS)fillers were prepared via electro static self-assembly method.And the corresponding thermally conductive&electrically insulating BNN-30@BNNS/Si-GFs/E-44 laminated composites were then fabricated via hot compression.BNN-30@BNNS-Ⅲ(fBNN-30/fBNNS,1/2,wt/wt)fillers presented the optimal synergistic improvement effects on the thermal conductivities of epoxy composites.When the mass fraction of BNN-30@BNNS-Ⅲwas 15 wt%,λvalue of the BNN-30@BNNS-Ⅲ/E-44 composites was up to0.61 W m^(-1)K^(-1),increased by 2.8 times compared with pure E-44(λ=0.22 W m^(-1)K^(-1)),also higher than that of the 15 wt%BNN-30/E-44(0.56 W m^(-1)K^(-1)),15 wt%BNNS/E-44(0.42 W m^(-1)K^(-1)),and 15 wt%(BNN-30/BNNS)/E-44(direct blending BNN-30/BNNS hybrid fillers,1/2,wt/wt,0.49 W m^(-1)K^(-1))composites.Theλin-plane(λ//)andλcross-plane(λ_(⊥))of 15 wt%BNN-30@BNNS-Ⅲ/Si-GFs/E-44 laminated composites significantly reached 2.75 W m^(-1)K^(-1)and 1.32 W m^(-1)K^(-1),186.5%and 187.0%higher than those of Si-GFs/E-44 laminated composites(λ//=0.96 W m^(-1)K^(-1)andλ_(⊥)=0.46 W m^(-1)K^(-1)).Established models can well simulate heat transfer efficiency in the BNN-30@BNNS-Ⅲ/Si-GFs/E-44 laminated composites.Under the condition of point heat source,the introduction of BNN-30@BNNS-Ⅲfillers were conducive to accelerating heat flow trans fe r.BNN-30@BNNS-Ⅲ/Si-GFs/E-44 laminated composites also demonstrated outstanding electrical insulating properties(cross-plane withstanding voltage,breakdown strength,surface&volume resistivity of 51.3 kV,23.8 kV mm^(-1),3.7×10^(14)Ω&3.4×10^(14)Ω·cm,favorable mechanical properties(flexural strength of 401.0 MPa and ILSS of 22.3 MPa),excellent dielectric properties(εof 4.92 and tanδof 0.008)and terrific thermal properties(T_(g)of 167.3℃and T_(HRI)of 199.2℃).
基金Project supported by the National Natural Science Foundation of China(Nos.11321062,91016008 and 91216107)
文摘Analytical studies on the vibration and sound radiation characteristics of an asymmetric laminated rectangular plate are carried out in this paper. Theoretical formulations, in which the effects of thermal environments are taken into account, are derived for the vibration and sound radiation based on both first-order shear deformation plate theory and Rayleigh integral. It is found that the natural frequencies, the resonant amplitudes of vibration response and the sound pressure level decrease with the temperature rising. The natural frequencies of asym- metric plates are smaller than those of symmetric plates and the velocity responses of asymmetric plates are larger than those of symmetric plates.
