We used hydrodynamic simulations and shock wave propagation theories to analyze the behavior of shock waves within Ti/Pt periodically modulated graded structures and their integration layers.The effects of the total n...We used hydrodynamic simulations and shock wave propagation theories to analyze the behavior of shock waves within Ti/Pt periodically modulated graded structures and their integration layers.The effects of the total number of periodic layers,the total thickness of graded materials and loading velocity on the integration layer thickness and behavior of pressure-strain rate were systematically investigated.The results reveal that,by adjusting the total number of periodically modulated layers,the total thickness of graded materials and loading velocity the pressure amplitudes of the reflected compressive and rarefaction waves at different interfaces of Ti/Pt periodically modulated graded materials can be precisely controlled.Furthermore,empirical structural design criteria for Ti/Pt periodically modulated graded materials are established.The thickness ratio variation between adjacent Ti/Pt layers in the periodic structure must exceed 0.32.After the collaborative design of the integration layer,Ti/Pt periodically modulated graded materials can achieve a controllable loading function with pressures ranging from 1.4 to 144 GPa and strain rates from 3.8×10^(4) to 1.7×10^(7) s^(–1).The outcomes of this research provide a theoretical and simulation basis for the optimized design of periodically modulated graded materials to be utilized in ramp compression experiments.展开更多
SS316L alloy coupled with Inconel625 alloy were combined with Ti6Al4V or Inconel718 alloy through wire arc additive manufacturing technique to manufacture functionally graded materials(FGMs).Two FGMs,namely 60%SS316L+...SS316L alloy coupled with Inconel625 alloy were combined with Ti6Al4V or Inconel718 alloy through wire arc additive manufacturing technique to manufacture functionally graded materials(FGMs).Two FGMs,namely 60%SS316L+20%Inconel625+20%Ti6Al4V composite and 60%SS316L+20%Inconel625+20%Inconel718 composite,were prepared.The tensile strength,elongation,yield strength,hardness,cross section area of the parent material,and composition were analysed.Results illustrate that the 60%SS316L+20%Inconel625+20%Inconel718 composite has better mechanical properties than 60%SS316L+20%Inconel625+20%Ti6Al4V composite,and the comprehensive properties of 60%SS316L+20%Inconel 625+20%Ti6Al4V composite are better than those of the parent material SS316L.Hence,the composite of 60%SS316L+20%Inconel625+20%Inconel718 is optimal.Due to its high strength,the 60%SS316L+20%Inconel625+20%Inconel718 composite has great application potential in the field of high pressure pneumatic tool and defence tool.展开更多
Based on simplified calculations of one-dimensional wave systems,loading pressure platform curves of Al-Cu gradient materials(GMs)impactor were designed.The Al-Cu GMs were prepared using tape-pressing sintering,and th...Based on simplified calculations of one-dimensional wave systems,loading pressure platform curves of Al-Cu gradient materials(GMs)impactor were designed.The Al-Cu GMs were prepared using tape-pressing sintering,and their acoustic properties were characterized to match the design path.The parallelism of the Al-Cu GM was confirmed using a three-dimensional surface profilometry machine.A one-stage light-gas gun was used to launch the Al-Cu GM,impacting an Al-LiF target at a velocity of 400 m/s.The results of the experimental strain rate demonstrate that the Al-Cu GMs can realize the precise control of the strain rate within the range of 10^(4)‒10^(5)/s in the high-speed impact experiments.展开更多
Fe-Mo functionally graded materials(FGMs)with different composition-change rates from 100%304 stainless steel to 100%Mo along the composition gradient direction were prepared by electron beam-directed energy depositio...Fe-Mo functionally graded materials(FGMs)with different composition-change rates from 100%304 stainless steel to 100%Mo along the composition gradient direction were prepared by electron beam-directed energy deposition(EB-DED)technique,including three samples with composition mutation of 100%,composition change rate of 10%and 30%.Results show that the composition-change rate significantly affects the microstructure and mechanical properties of the samples.In the sample with abrupt change of composition,the sharp shift in composition between 304 stainless steel and Mo leads to a great difference in the microstructure and hardness near the interface between the two materials.With the increase in the number of gradient layers,the composition changes continuously along the direction of deposition height,and the microstructure morphology shows a smooth transition from 304 stainless steel to Mo,which is gradually transformed from columnar crystal to dendritic crystal.Elements Fe,Mo,and other major elements transform linearly along the gradient direction,with sufficient interlayer diffusion between the deposited layers,leading to good metallurgical bonding.The smaller the change in composition gradient,the greater the microhardness value along the deposition direction.When the composition gradient is 10%,the gradient layer exhibits higher hardness(940 HV)and excellent resistance to surface abrasion,and the overall compressive properties of the samples are better,with the compressive fracture stress in the top region reaching 750.05±14 MPa.展开更多
Mechanical loading constitutes a fundamental determinant in the process of bone remodeling.This modeling encompasses the incorporation of mechanical stimuli,the involvement of cellular and molecular constituents,as we...Mechanical loading constitutes a fundamental determinant in the process of bone remodeling.This modeling encompasses the incorporation of mechanical stimuli,the involvement of cellular and molecular constituents,as well as the utilization of sophisticated computational methodologies.Such an approach is imperative for forecasting bone behaviour across varying environmental conditions.In the present study,key findings from bone mechanobiology are reviewed,along with the possibility that Functionally Graded Materials(FGM)enhances osseointegration and lowers the stress-shielding effect during bone remodeling and compared to titanium,FGM improves periprosthetic bone remodeling.To summarise some of the most important findings from computational models of bone mechanobiology,explaining how modifications to the mechanical environment affect implant design,growth of bone,and bone response.The impact that changes related to the mechanical environment have on bone response is examined using computational models and methods such as surface microtopography to determine how an implant’s bone density has increased over time.This review focuses on the refinement of advanced simulation frameworks and their synergy with imaging technologies to strengthen model validation,ultimately resulting in better clinical outcomes in the context of bone health treatments.展开更多
The fabrication of Invar/MnCu functionally graded material(FGM)through directed energy deposition(DED)can satisfy the demands for precision devices in aerospace,providing lightweight properties and integrating thermal...The fabrication of Invar/MnCu functionally graded material(FGM)through directed energy deposition(DED)can satisfy the demands for precision devices in aerospace,providing lightweight properties and integrating thermal stability and vibration damping capabilities.However,basic research on Invar/MnCu FGM is still lacking,hindering its potential applications.To address this gap,this study was conducted using mixed powders and consistent process parameters to print experiments for Invar/MnCu FGM and homogeneous samples.Phases,microstructures,compositions,and thermal expansion properties were thoroughly examined.Three types of defects were detected in the Invar/MnCu FGM sample:unmelted Invar 36 powders,cracks,and pores.The mechanism of unmelted powders was deeply discussed,attributing it to material properties influencing laser absorptivity,the required time for melting powder,and effects on solidus temperature.The mechanism of cracks was also discussed,attributing it to theγ-Fe dendritic structure causing low melting point metal to form an intergranular liquid film,harmful secondary phases mismatched with the terminal alloy,and obvious tensile stresses during the DED process.Additionally,an effective strategy was proposed to reduce defects in Invar/MnCu FGM.After optimization,the specimens exhibited excellent tensile properties,with a yield strength of 262±5 MPa,an ultimate tensile strength of 316±7 MPa,and an elongation of 3%±1%.This research provides valuable references and insights for subsequent work,offering robust support for better understanding and designing other FGM.展开更多
Functionally graded materials (FGMs) are innovative materials distinguished by gradual variations in composition and structure, offering exceptional properties for diverse applications. Poly(ionic liquid)s (PILs), mer...Functionally graded materials (FGMs) are innovative materials distinguished by gradual variations in composition and structure, offering exceptional properties for diverse applications. Poly(ionic liquid)s (PILs), merging the characteristics of polymers and ionic liquids, have emerged as viable options for the development of FGMs given their tunable skeleton, ionic conductivity, and compatibility with various functional materials. This review highlights the latest advancements in the design strategies of FGMs based on porous PILs, focusing on single and multi-gradient structures. Furthermore, we also highlight their emerging applications in molecular recognition, sensing, adsorption, separation, and catalysis. By exploring the interplay between porosity, ionic functionality, and gradient architecture, this review offers perspectives on the prospects of PIL-based FGMs for tackling global challenges in energy, environment, and healthcare.展开更多
Traditional gear weight optimization methods consider gear tooth number, module, face width or other dimension parameters of gear as design variables. However, due to the complicated form and geometric features peculi...Traditional gear weight optimization methods consider gear tooth number, module, face width or other dimension parameters of gear as design variables. However, due to the complicated form and geometric features peculiar to the gear, there will be large amounts of design parameters in gear design, and the influences of gear parameters changing on gear trains, transmission system and the whole equipment have to be taken into account, which increases the complexity of optimization problem. This paper puts forward to apply functionally graded materials（FGMs） to gears and then conduct the optimization. According to the force situation of gears, the material distribution form of FGM gears is determined. Then based on the performance parameters analysis of FGMs and the practical working demands for gears, a multi-objective optimization model is formed. Finally by using the goal driven optimization（GDO） method, the optimal material distribution is achieved, which makes gear weight and the maximum deformation be minimum and the maximum bending stress do not exceed the allowable stress. As an example, the applying of FGM to automotive transmission gear is conducted to illustrate the optimization design process and the result shows that under the condition of keeping the normal working performance of gear, the method achieves in greatly reducing the gear weight. This research proposes a FGM gears design method that is able to largely reduce the weight of gears by optimizing the microscopic material parameters instead of changing the macroscopic dimension parameters of gears, which reduces the complexity of gear weight optimization problem.展开更多
Additive manufacturing enables processing of functionally graded materials(FGMs)with flexible spatial design and high bonding strength.A steel-copper FGM with high interfacial strength was developed using laser powder...Additive manufacturing enables processing of functionally graded materials(FGMs)with flexible spatial design and high bonding strength.A steel-copper FGM with high interfacial strength was developed using laser powder bed fusion(LPBF).The effect of laser process parameters on interfacial defects was evaluated by X-ray tomography,which indicates a low porosity level of 0.042%therein.Gradient/fine dendritic grains in the interface are incited by high cooling rates,which facilitates interface strengthening.Multiple mechanical tests evaluate the bonding reliability of interface;and the fatigue tests further substantiate the ultrahigh bonding strength in FGMs,which is superior to traditional manufacturing methods.Mechanisms of the high interfacial bond strength were also discussed.展开更多
Functionally graded materials, including their characterization, properties and production methods are a new rapidly developing field of materials science. The aims of this review are to systematize the basic producti...Functionally graded materials, including their characterization, properties and production methods are a new rapidly developing field of materials science. The aims of this review are to systematize the basic production techniques for manufacturing functionally graded materials. Attention is paid to the principles for obtaining graded structure mainly in the metal based functionally graded materials. Several unpublished results obtained by the authors have been discussed briefly. Experimental methods and theoretical analysis for qualitative and quantitative estimation of graded properties have also been presented. The article can be useful for people who work in the field of functionally graded structures and materials, and who need a compact informative review of recent experimental and theoretical activity in this area.展开更多
Functionally graded material(FGM)can tailor properties of components such as wear resistance,corrosion resistance,and functionality to enhance the overall performance.The selective laser melting(SLM)additive manufactu...Functionally graded material(FGM)can tailor properties of components such as wear resistance,corrosion resistance,and functionality to enhance the overall performance.The selective laser melting(SLM)additive manufacturing highlights the capability in manufacturing FGMs with a high geometrical complexity and manufacture flexibility.In this work,the 316L/CuSn10/18Ni300/CoCr four-type materials FGMs were fabricated using SLM.The microstructure and properties of the FGMs were investigated to reveal the effects of SLM processing parameters on the defects.A large number of microcracks were found at the 316L/CuSn10 interface,which initiated from the fusion boundary of 316L region and extended along the building direction.The elastic modulus and nano-hardness in the 18Ni300/CoCr fusion zone decreased significantly,less than those in the 18Ni300 region or the CoCr region.The iron and copper elements were well diffused in the 316L/CuSn10 fusion zone,while elements in the CuSn10/18Ni300 and the 18Ni300/CoCr fusion zones showed significantly gradient transitions.Compared with other regions,the width of the CuSn10/18Ni300 interface and the CuSn10 region expand significantly.The mechanisms of materials fusion and crack generation at the 316L/CuSn10 interface were discussed.In addition,FGM structures without macro-crack were built by only altering the deposition subsequence of 316L and CuSn10,which provides a guide for the additive manufacturing of FGM structures.展开更多
This paper considers the pure bending problem of simply supported transversely isotropic circular plates with elastic compliance coefficients being arbitrary functions of the thickness coordinate. First, the partial d...This paper considers the pure bending problem of simply supported transversely isotropic circular plates with elastic compliance coefficients being arbitrary functions of the thickness coordinate. First, the partial differential equation, which is satisfied by the stress functions for the axisymmetric deformation problem is derived. Then, stress functions are obtained by proper manipulation. The analytical expressions of axial force, bending moment and displacements are then deduced through integration. And then, stress functions are employed to solve problems of transversely isotropic functionally graded circular plate, with the integral constants completely determined from boundary conditions. An elasticity solution for pure bending problem, which coincides with the available solution when degenerated into the elasticity solutions for homogenous circular plate, is thus obtained. A numerical example is finally presented to show the effect of material inhomogeneity on the elastic field in a simply supported circular plate of transversely isotropic functionally graded material (FGM).展开更多
Free vibration of statically thermal postbuckled functionally graded material （FGM） beams with surface-bonded piezoelectric layers subject to both temperature rise and voltage is studied. By accurately considering t...Free vibration of statically thermal postbuckled functionally graded material （FGM） beams with surface-bonded piezoelectric layers subject to both temperature rise and voltage is studied. By accurately considering the axial extension and based on the Euler-Bernoulli beam theory, geometrically nonlinear dynamic governing equations for FGM beams with surface-bonded piezoelectric layers subject to thermo-electro- mechanical loadings are formulated. It is assumed that the material properties of the middle FGM layer vary continuously as a power law function of the thickness coordinate, and the piezoelectric layers are isotropic and homogenous. By assuming that the amplitude of the beam vibration is small and its response is harmonic, the above mentioned non-linear partial differential equations are reduced to two sets of coupled ordinary differential equations. One is for the postbuckling, and the other is for the linear vibration of the beam superimposed upon the postbuckled configuration. Using a shooting method to solve the two sets of ordinary differential equations with fixed-fixed boundary conditions numerically, the response of postbuckling and free vibration in the vicinity of the postbuckled configuration of the beam with fixed-fixed ends and subject to transversely nonuniform heating and uniform electric field is obtained. Thermo-electric postbuckling equilibrium paths and characteristic curves of the first three natural frequencies versus the temperature, the electricity, and the material gradient parameters are plotted. It is found that the three lowest frequencies of the prebuckled beam decrease with the increase of the temperature, but those of a buckled beam increase monotonically with the temperature rise. The results also show that the tensional force produced in the piezoelectric layers by the voltage can efficiently increase the critical buckling temperature and the natural frequency.展开更多
In this paper,the dynamic interaction of two parallel cracks in functionally graded materials(FGMs)is investigated by means of the non-local theory.To make the analysis tractable,the shear modulus and the material den...In this paper,the dynamic interaction of two parallel cracks in functionally graded materials(FGMs)is investigated by means of the non-local theory.To make the analysis tractable,the shear modulus and the material density are assumed to vary exponentially with the coordinate vertical to the crack.To reduce mathematical difficulties,a one-dimensional non-local kernel is used instead of a twodimensional one for the dynamic problem to obtain stress fields near the crack tips.By use of the Fourier transform,the problem can be solved with the help of two pairs of dual integral equations,in which the unknown variables are the jumps of displacements across the crack surfaces.To solve the dual integral equations,the jumps of displacements across the crack surfaces are expanded in a series of Jacobi polynomials.Unlike the classical elasticity solutions,it is found that no stress singularity is present at the crack tips.The non-local elastic solutions yield a finite hoop stress at the crack tips.The present result provides theoretical references helpful for evaluating relevant strength and preventing material failure of FGMs with initial cracks.The magnitude of the finite stress field depends on relevant parameters,such as the crack length,the distance between two parallel cracks,the parameter describing the FGMs,the frequency of the incident waves and the lattice parameter of materials.展开更多
The distribution of thermal stresses in functionally graded polycrystalline diamond compact (PDC) and in single coating of PDC are analyzed respectively by thermo-mechanical finite element analysis (FEA). It is shown ...The distribution of thermal stresses in functionally graded polycrystalline diamond compact (PDC) and in single coating of PDC are analyzed respectively by thermo-mechanical finite element analysis (FEA). It is shown that they each have a remarkable stress concentration at the edge of the interfaces. The diamond coatings usually suffer premature failure because of spallation, distortion or defects such as cracks near the interface due to these excessive residual stresses. Results showed that the axial tensile stress in FGM coating is reduced from 840 MPa to 229 MPa compared with single coating, and that the shear stress is reduced from 671 MPa to 471 MPa. Therefore, the single coating is more prone to spallation and cracking than the FGM coating. The effects of the volume compositional distribution factor (n) and the number of the graded layers (L) on the thermal stresses in FGM coating are also discussed respectively. Modelling results showed that the optimum value of the compositional distribution factor is 1.2, and that the best number of the graded layers is 6.展开更多
Free vibration response of functionally graded material （FGM） beams is studied based on the Levinson beam theory （LBT）. Equations of motion of an FGM beam are derived by directly integrating the stress-form equati...Free vibration response of functionally graded material （FGM） beams is studied based on the Levinson beam theory （LBT）. Equations of motion of an FGM beam are derived by directly integrating the stress-form equations of elasticity along the beam depth with the inertial resultant forces related to the included coupling and higherorder shear strain. Assuming harmonic response, governing equations of the free vibration of the FGM beam are reduced to a standard system of second-order ordinary differential equations associated with boundary conditions in terms of shape functions related to axial and transverse displacements and the rotational angle. By a shooting method to solve the two-point boundary value problem of the three coupled ordinary differential equations, free vibration response of thick FGM beams is obtained numerically. Particularly, for a beam with simply supported edges, the natural frequency of an FGM Levinson beam is analytically derived in terms of the natural frequency of a corresponding homogenous Euler-Bernoulli beam. As the material properties are assumed to vary through the depth according to the power-law functions, the numerical results of frequencies are presented to examine the effects of the material gradient parameter, the length-to-depth ratio, and the boundary conditions on the vibration response.展开更多
From the process of sedimentation the mathematical relationships among deposition Volume and powder properties as well as sedimentation parameters were deduced. Based on the formula a mathematical model was set up and...From the process of sedimentation the mathematical relationships among deposition Volume and powder properties as well as sedimentation parameters were deduced. Based on the formula a mathematical model was set up and simulated through the computer. At last the validity of mathematical model was supported by the representative experiment on Ti-Mo system FGM prepared by co-sedimentation.展开更多
In extreme heat transfer environments, functionally graded materials(FGMs)have aroused great concern due to the excellent thermal shock resistance. With the development of micro-scale devices, the size-dependent effec...In extreme heat transfer environments, functionally graded materials(FGMs)have aroused great concern due to the excellent thermal shock resistance. With the development of micro-scale devices, the size-dependent effect has become an important issue. However, the classical continuum mechanical model fails on the micro-scale due to the influence of the size-dependent effect. Meanwhile, for thermoelastic behaviors limited to small-scale problems, Fourier's heat conduction law cannot explain the thermal wave effect. In order to capture the size-dependent effect and the thermal wave effect, the nonlocal generalized thermoelastic theory for the formulation of an FGM microbeam is adopted in the present work. For numerical validation, the transient responses for a simply supported FGM microbeam heated by the ramp-type heating are considered.The governing equations are formulated and solved by employing the Laplace transform techniques. In the numerical results, the effects of the ramp-heating time parameter, the nonlocal parameter, and the power-law index on the considered physical quantities are presented and discussed in detail.展开更多
The present work is concerned with the solution of a problem on thermoelastic interactions in a functional graded material due to thermal shock in the context of the fractional order three-phase lag model. The governi...The present work is concerned with the solution of a problem on thermoelastic interactions in a functional graded material due to thermal shock in the context of the fractional order three-phase lag model. The governing equations of fractional order generalized thermoelasticity with three-phase lag model for functionally graded materials(FGM)(i.e., material with spatially varying material properties) are established. The analytical solution in the transform domain is obtained by using the eigenvalue approach.The inversion of Laplace transform is done numerically. The graphical results indicate that the fractional parameter has significant effects on all the physical quantities. Thus, we can consider the theory of fractional order generalized thermoelasticity an improvement on studying elastic materials.展开更多
For quartz crystal resonators of thickness-shear type,the vibration frequency and mode shapes reflect the basic material and structural properties of a quartz crystal plate and the variation with time under attack by ...For quartz crystal resonators of thickness-shear type,the vibration frequency and mode shapes reflect the basic material and structural properties of a quartz crystal plate and the variation with time under attack by erosive gases and liquids that can cause surface and internal degradation in a graded form.Such gradual effects,in turn,will change surface conditions through elastic constants and stiffness and more importantly the gradient of such properties across the thickness with certain depth.Now we study the thickness-shear vibrations of functionally graded material plates with properties of the popular AT-cut quartz crystal varying across the thickness in a general pattern represented by both sine and cosine components of the thickness.The vibration solutions are obtained through the Fourier expansion of the plate deformation.展开更多
基金Funded by the Guangdong Major Project of Basic and Applied Basic Research(No.2021B0301030001)the Foundation of National Key Laboratory of Shock Wave and Detonation Physics(No.JCKYS2022212004)。
文摘We used hydrodynamic simulations and shock wave propagation theories to analyze the behavior of shock waves within Ti/Pt periodically modulated graded structures and their integration layers.The effects of the total number of periodic layers,the total thickness of graded materials and loading velocity on the integration layer thickness and behavior of pressure-strain rate were systematically investigated.The results reveal that,by adjusting the total number of periodically modulated layers,the total thickness of graded materials and loading velocity the pressure amplitudes of the reflected compressive and rarefaction waves at different interfaces of Ti/Pt periodically modulated graded materials can be precisely controlled.Furthermore,empirical structural design criteria for Ti/Pt periodically modulated graded materials are established.The thickness ratio variation between adjacent Ti/Pt layers in the periodic structure must exceed 0.32.After the collaborative design of the integration layer,Ti/Pt periodically modulated graded materials can achieve a controllable loading function with pressures ranging from 1.4 to 144 GPa and strain rates from 3.8×10^(4) to 1.7×10^(7) s^(–1).The outcomes of this research provide a theoretical and simulation basis for the optimized design of periodically modulated graded materials to be utilized in ramp compression experiments.
文摘SS316L alloy coupled with Inconel625 alloy were combined with Ti6Al4V or Inconel718 alloy through wire arc additive manufacturing technique to manufacture functionally graded materials(FGMs).Two FGMs,namely 60%SS316L+20%Inconel625+20%Ti6Al4V composite and 60%SS316L+20%Inconel625+20%Inconel718 composite,were prepared.The tensile strength,elongation,yield strength,hardness,cross section area of the parent material,and composition were analysed.Results illustrate that the 60%SS316L+20%Inconel625+20%Inconel718 composite has better mechanical properties than 60%SS316L+20%Inconel625+20%Ti6Al4V composite,and the comprehensive properties of 60%SS316L+20%Inconel 625+20%Ti6Al4V composite are better than those of the parent material SS316L.Hence,the composite of 60%SS316L+20%Inconel625+20%Inconel718 is optimal.Due to its high strength,the 60%SS316L+20%Inconel625+20%Inconel718 composite has great application potential in the field of high pressure pneumatic tool and defence tool.
基金Natural Science Foundation of Hubei Province(2024AFB432)National Natural Science Foundation of China(52171045,12302436,52302095)Research Fund of Jianghan University(2023JCYJ05)。
文摘Based on simplified calculations of one-dimensional wave systems,loading pressure platform curves of Al-Cu gradient materials(GMs)impactor were designed.The Al-Cu GMs were prepared using tape-pressing sintering,and their acoustic properties were characterized to match the design path.The parallelism of the Al-Cu GM was confirmed using a three-dimensional surface profilometry machine.A one-stage light-gas gun was used to launch the Al-Cu GM,impacting an Al-LiF target at a velocity of 400 m/s.The results of the experimental strain rate demonstrate that the Al-Cu GMs can realize the precise control of the strain rate within the range of 10^(4)‒10^(5)/s in the high-speed impact experiments.
基金National Natural Science Foundation of China(51975286)。
文摘Fe-Mo functionally graded materials(FGMs)with different composition-change rates from 100%304 stainless steel to 100%Mo along the composition gradient direction were prepared by electron beam-directed energy deposition(EB-DED)technique,including three samples with composition mutation of 100%,composition change rate of 10%and 30%.Results show that the composition-change rate significantly affects the microstructure and mechanical properties of the samples.In the sample with abrupt change of composition,the sharp shift in composition between 304 stainless steel and Mo leads to a great difference in the microstructure and hardness near the interface between the two materials.With the increase in the number of gradient layers,the composition changes continuously along the direction of deposition height,and the microstructure morphology shows a smooth transition from 304 stainless steel to Mo,which is gradually transformed from columnar crystal to dendritic crystal.Elements Fe,Mo,and other major elements transform linearly along the gradient direction,with sufficient interlayer diffusion between the deposited layers,leading to good metallurgical bonding.The smaller the change in composition gradient,the greater the microhardness value along the deposition direction.When the composition gradient is 10%,the gradient layer exhibits higher hardness(940 HV)and excellent resistance to surface abrasion,and the overall compressive properties of the samples are better,with the compressive fracture stress in the top region reaching 750.05±14 MPa.
文摘Mechanical loading constitutes a fundamental determinant in the process of bone remodeling.This modeling encompasses the incorporation of mechanical stimuli,the involvement of cellular and molecular constituents,as well as the utilization of sophisticated computational methodologies.Such an approach is imperative for forecasting bone behaviour across varying environmental conditions.In the present study,key findings from bone mechanobiology are reviewed,along with the possibility that Functionally Graded Materials(FGM)enhances osseointegration and lowers the stress-shielding effect during bone remodeling and compared to titanium,FGM improves periprosthetic bone remodeling.To summarise some of the most important findings from computational models of bone mechanobiology,explaining how modifications to the mechanical environment affect implant design,growth of bone,and bone response.The impact that changes related to the mechanical environment have on bone response is examined using computational models and methods such as surface microtopography to determine how an implant’s bone density has increased over time.This review focuses on the refinement of advanced simulation frameworks and their synergy with imaging technologies to strengthen model validation,ultimately resulting in better clinical outcomes in the context of bone health treatments.
基金supported by the National Key Research and Development Program of China(Nos.2022YFB4600300 and 2022YFB4600301)the National Natural Science Foundation of China(No.52175364)+1 种基金the ND Basic Research Funds of NPU(G2022WD)the Research Fund of the State Key Laboratory of Solidification Processing(NPU),China(No.2023-QZ-04).
文摘The fabrication of Invar/MnCu functionally graded material(FGM)through directed energy deposition(DED)can satisfy the demands for precision devices in aerospace,providing lightweight properties and integrating thermal stability and vibration damping capabilities.However,basic research on Invar/MnCu FGM is still lacking,hindering its potential applications.To address this gap,this study was conducted using mixed powders and consistent process parameters to print experiments for Invar/MnCu FGM and homogeneous samples.Phases,microstructures,compositions,and thermal expansion properties were thoroughly examined.Three types of defects were detected in the Invar/MnCu FGM sample:unmelted Invar 36 powders,cracks,and pores.The mechanism of unmelted powders was deeply discussed,attributing it to material properties influencing laser absorptivity,the required time for melting powder,and effects on solidus temperature.The mechanism of cracks was also discussed,attributing it to theγ-Fe dendritic structure causing low melting point metal to form an intergranular liquid film,harmful secondary phases mismatched with the terminal alloy,and obvious tensile stresses during the DED process.Additionally,an effective strategy was proposed to reduce defects in Invar/MnCu FGM.After optimization,the specimens exhibited excellent tensile properties,with a yield strength of 262±5 MPa,an ultimate tensile strength of 316±7 MPa,and an elongation of 3%±1%.This research provides valuable references and insights for subsequent work,offering robust support for better understanding and designing other FGM.
基金support provided by National Natural Science Foundation of China(22471018,22071008,22208018)support provided by the Shenzhen Science and Technology Program(JCYJ20220818100012025).
文摘Functionally graded materials (FGMs) are innovative materials distinguished by gradual variations in composition and structure, offering exceptional properties for diverse applications. Poly(ionic liquid)s (PILs), merging the characteristics of polymers and ionic liquids, have emerged as viable options for the development of FGMs given their tunable skeleton, ionic conductivity, and compatibility with various functional materials. This review highlights the latest advancements in the design strategies of FGMs based on porous PILs, focusing on single and multi-gradient structures. Furthermore, we also highlight their emerging applications in molecular recognition, sensing, adsorption, separation, and catalysis. By exploring the interplay between porosity, ionic functionality, and gradient architecture, this review offers perspectives on the prospects of PIL-based FGMs for tackling global challenges in energy, environment, and healthcare.
基金Supported by National Hi-tech Research and Development Program of China(863 Program,Grant No.2015AA042505)
文摘Traditional gear weight optimization methods consider gear tooth number, module, face width or other dimension parameters of gear as design variables. However, due to the complicated form and geometric features peculiar to the gear, there will be large amounts of design parameters in gear design, and the influences of gear parameters changing on gear trains, transmission system and the whole equipment have to be taken into account, which increases the complexity of optimization problem. This paper puts forward to apply functionally graded materials（FGMs） to gears and then conduct the optimization. According to the force situation of gears, the material distribution form of FGM gears is determined. Then based on the performance parameters analysis of FGMs and the practical working demands for gears, a multi-objective optimization model is formed. Finally by using the goal driven optimization（GDO） method, the optimal material distribution is achieved, which makes gear weight and the maximum deformation be minimum and the maximum bending stress do not exceed the allowable stress. As an example, the applying of FGM to automotive transmission gear is conducted to illustrate the optimization design process and the result shows that under the condition of keeping the normal working performance of gear, the method achieves in greatly reducing the gear weight. This research proposes a FGM gears design method that is able to largely reduce the weight of gears by optimizing the microscopic material parameters instead of changing the macroscopic dimension parameters of gears, which reduces the complexity of gear weight optimization problem.
基金financially supported by the Guangdong Basic and Applied Basic Research Foundation(No.2019A1515110542)the Guangdong Special Support Program(No.2019BT02C629)+5 种基金the National Natural Science Foundation of China(Nos.52005189and 51775196)the Chinese Postdoctoral Science Foundation(No.2020M672617)the Guangzhou Science and Technology Society Project(Nos.X20200301015,201907010008,202007020008and 201807010030)the Chinese Central Universities Funds(No.2018ZD30)supported by Guangdong province Science and Technology Plan Projects(No.2019A1515011841)GDAS Projects(Nos.2020GDASYL-20200402005,2019GDASYL-0501009,2019GDASYL-0502006,2018GDASCX-0111,2018GDASCX-0402 and 2019GDASYL-0402004)。
文摘Additive manufacturing enables processing of functionally graded materials(FGMs)with flexible spatial design and high bonding strength.A steel-copper FGM with high interfacial strength was developed using laser powder bed fusion(LPBF).The effect of laser process parameters on interfacial defects was evaluated by X-ray tomography,which indicates a low porosity level of 0.042%therein.Gradient/fine dendritic grains in the interface are incited by high cooling rates,which facilitates interface strengthening.Multiple mechanical tests evaluate the bonding reliability of interface;and the fatigue tests further substantiate the ultrahigh bonding strength in FGMs,which is superior to traditional manufacturing methods.Mechanisms of the high interfacial bond strength were also discussed.
文摘Functionally graded materials, including their characterization, properties and production methods are a new rapidly developing field of materials science. The aims of this review are to systematize the basic production techniques for manufacturing functionally graded materials. Attention is paid to the principles for obtaining graded structure mainly in the metal based functionally graded materials. Several unpublished results obtained by the authors have been discussed briefly. Experimental methods and theoretical analysis for qualitative and quantitative estimation of graded properties have also been presented. The article can be useful for people who work in the field of functionally graded structures and materials, and who need a compact informative review of recent experimental and theoretical activity in this area.
基金Project(2020B090922002)supported by Guangdong Provincial Key Field Research and Development Program,ChinaProjects(51875215,52005189)supported by the National Natural Science Foundation of ChinaProject(2019B1515120094)supported by Guangdong Provincial Basic and Applied Basic Research Fund,China。
文摘Functionally graded material(FGM)can tailor properties of components such as wear resistance,corrosion resistance,and functionality to enhance the overall performance.The selective laser melting(SLM)additive manufacturing highlights the capability in manufacturing FGMs with a high geometrical complexity and manufacture flexibility.In this work,the 316L/CuSn10/18Ni300/CoCr four-type materials FGMs were fabricated using SLM.The microstructure and properties of the FGMs were investigated to reveal the effects of SLM processing parameters on the defects.A large number of microcracks were found at the 316L/CuSn10 interface,which initiated from the fusion boundary of 316L region and extended along the building direction.The elastic modulus and nano-hardness in the 18Ni300/CoCr fusion zone decreased significantly,less than those in the 18Ni300 region or the CoCr region.The iron and copper elements were well diffused in the 316L/CuSn10 fusion zone,while elements in the CuSn10/18Ni300 and the 18Ni300/CoCr fusion zones showed significantly gradient transitions.Compared with other regions,the width of the CuSn10/18Ni300 interface and the CuSn10 region expand significantly.The mechanisms of materials fusion and crack generation at the 316L/CuSn10 interface were discussed.In addition,FGM structures without macro-crack were built by only altering the deposition subsequence of 316L and CuSn10,which provides a guide for the additive manufacturing of FGM structures.
基金Project (Nos. 10472102 and 10432030) supported by the NationalNatural Science Foundation of China
文摘This paper considers the pure bending problem of simply supported transversely isotropic circular plates with elastic compliance coefficients being arbitrary functions of the thickness coordinate. First, the partial differential equation, which is satisfied by the stress functions for the axisymmetric deformation problem is derived. Then, stress functions are obtained by proper manipulation. The analytical expressions of axial force, bending moment and displacements are then deduced through integration. And then, stress functions are employed to solve problems of transversely isotropic functionally graded circular plate, with the integral constants completely determined from boundary conditions. An elasticity solution for pure bending problem, which coincides with the available solution when degenerated into the elasticity solutions for homogenous circular plate, is thus obtained. A numerical example is finally presented to show the effect of material inhomogeneity on the elastic field in a simply supported circular plate of transversely isotropic functionally graded material (FGM).
基金supported by the National Natural Science Foundation of China (Nos. 10872083 and10602021)the Doctoral Foundation of Ministry of Education of China (No. 200807310002)
文摘Free vibration of statically thermal postbuckled functionally graded material （FGM） beams with surface-bonded piezoelectric layers subject to both temperature rise and voltage is studied. By accurately considering the axial extension and based on the Euler-Bernoulli beam theory, geometrically nonlinear dynamic governing equations for FGM beams with surface-bonded piezoelectric layers subject to thermo-electro- mechanical loadings are formulated. It is assumed that the material properties of the middle FGM layer vary continuously as a power law function of the thickness coordinate, and the piezoelectric layers are isotropic and homogenous. By assuming that the amplitude of the beam vibration is small and its response is harmonic, the above mentioned non-linear partial differential equations are reduced to two sets of coupled ordinary differential equations. One is for the postbuckling, and the other is for the linear vibration of the beam superimposed upon the postbuckled configuration. Using a shooting method to solve the two sets of ordinary differential equations with fixed-fixed boundary conditions numerically, the response of postbuckling and free vibration in the vicinity of the postbuckled configuration of the beam with fixed-fixed ends and subject to transversely nonuniform heating and uniform electric field is obtained. Thermo-electric postbuckling equilibrium paths and characteristic curves of the first three natural frequencies versus the temperature, the electricity, and the material gradient parameters are plotted. It is found that the three lowest frequencies of the prebuckled beam decrease with the increase of the temperature, but those of a buckled beam increase monotonically with the temperature rise. The results also show that the tensional force produced in the piezoelectric layers by the voltage can efficiently increase the critical buckling temperature and the natural frequency.
基金The project supported by the National Natural Science Foundation of China(90405016,10572044)the Specialized Research Fund for the Doctoral Program of Higher Education(20040213034)
文摘In this paper,the dynamic interaction of two parallel cracks in functionally graded materials(FGMs)is investigated by means of the non-local theory.To make the analysis tractable,the shear modulus and the material density are assumed to vary exponentially with the coordinate vertical to the crack.To reduce mathematical difficulties,a one-dimensional non-local kernel is used instead of a twodimensional one for the dynamic problem to obtain stress fields near the crack tips.By use of the Fourier transform,the problem can be solved with the help of two pairs of dual integral equations,in which the unknown variables are the jumps of displacements across the crack surfaces.To solve the dual integral equations,the jumps of displacements across the crack surfaces are expanded in a series of Jacobi polynomials.Unlike the classical elasticity solutions,it is found that no stress singularity is present at the crack tips.The non-local elastic solutions yield a finite hoop stress at the crack tips.The present result provides theoretical references helpful for evaluating relevant strength and preventing material failure of FGMs with initial cracks.The magnitude of the finite stress field depends on relevant parameters,such as the crack length,the distance between two parallel cracks,the parameter describing the FGMs,the frequency of the incident waves and the lattice parameter of materials.
基金Research Program in the Ninth National Five-Year-Plan of Ministryof Land and Resources, China
文摘The distribution of thermal stresses in functionally graded polycrystalline diamond compact (PDC) and in single coating of PDC are analyzed respectively by thermo-mechanical finite element analysis (FEA). It is shown that they each have a remarkable stress concentration at the edge of the interfaces. The diamond coatings usually suffer premature failure because of spallation, distortion or defects such as cracks near the interface due to these excessive residual stresses. Results showed that the axial tensile stress in FGM coating is reduced from 840 MPa to 229 MPa compared with single coating, and that the shear stress is reduced from 671 MPa to 471 MPa. Therefore, the single coating is more prone to spallation and cracking than the FGM coating. The effects of the volume compositional distribution factor (n) and the number of the graded layers (L) on the thermal stresses in FGM coating are also discussed respectively. Modelling results showed that the optimum value of the compositional distribution factor is 1.2, and that the best number of the graded layers is 6.
基金supported by the National Natural Science Foundation of China(No.11272278)
文摘Free vibration response of functionally graded material （FGM） beams is studied based on the Levinson beam theory （LBT）. Equations of motion of an FGM beam are derived by directly integrating the stress-form equations of elasticity along the beam depth with the inertial resultant forces related to the included coupling and higherorder shear strain. Assuming harmonic response, governing equations of the free vibration of the FGM beam are reduced to a standard system of second-order ordinary differential equations associated with boundary conditions in terms of shape functions related to axial and transverse displacements and the rotational angle. By a shooting method to solve the two-point boundary value problem of the three coupled ordinary differential equations, free vibration response of thick FGM beams is obtained numerically. Particularly, for a beam with simply supported edges, the natural frequency of an FGM Levinson beam is analytically derived in terms of the natural frequency of a corresponding homogenous Euler-Bernoulli beam. As the material properties are assumed to vary through the depth according to the power-law functions, the numerical results of frequencies are presented to examine the effects of the material gradient parameter, the length-to-depth ratio, and the boundary conditions on the vibration response.
文摘From the process of sedimentation the mathematical relationships among deposition Volume and powder properties as well as sedimentation parameters were deduced. Based on the formula a mathematical model was set up and simulated through the computer. At last the validity of mathematical model was supported by the representative experiment on Ti-Mo system FGM prepared by co-sedimentation.
基金Project supported by the National Natural Science Foundation of China (Nos. 11972176 and12062011)the Incubation Programme of Excellent Doctoral Dissertation-Lanzhou University of Technology。
文摘In extreme heat transfer environments, functionally graded materials(FGMs)have aroused great concern due to the excellent thermal shock resistance. With the development of micro-scale devices, the size-dependent effect has become an important issue. However, the classical continuum mechanical model fails on the micro-scale due to the influence of the size-dependent effect. Meanwhile, for thermoelastic behaviors limited to small-scale problems, Fourier's heat conduction law cannot explain the thermal wave effect. In order to capture the size-dependent effect and the thermal wave effect, the nonlocal generalized thermoelastic theory for the formulation of an FGM microbeam is adopted in the present work. For numerical validation, the transient responses for a simply supported FGM microbeam heated by the ramp-type heating are considered.The governing equations are formulated and solved by employing the Laplace transform techniques. In the numerical results, the effects of the ramp-heating time parameter, the nonlocal parameter, and the power-law index on the considered physical quantities are presented and discussed in detail.
文摘The present work is concerned with the solution of a problem on thermoelastic interactions in a functional graded material due to thermal shock in the context of the fractional order three-phase lag model. The governing equations of fractional order generalized thermoelasticity with three-phase lag model for functionally graded materials(FGM)(i.e., material with spatially varying material properties) are established. The analytical solution in the transform domain is obtained by using the eigenvalue approach.The inversion of Laplace transform is done numerically. The graphical results indicate that the fractional parameter has significant effects on all the physical quantities. Thus, we can consider the theory of fractional order generalized thermoelasticity an improvement on studying elastic materials.
基金the National Natural Science Foundation of China(Grant Nos.10932004,11072116,and 11372145)K.C.Wong Magna Fund administered by Ningbo UniversityA dditional supports are from the Research Project Foundation of Zhejiang Department of Education(Grant Nos.Y201636501 and Y201738413).
文摘For quartz crystal resonators of thickness-shear type,the vibration frequency and mode shapes reflect the basic material and structural properties of a quartz crystal plate and the variation with time under attack by erosive gases and liquids that can cause surface and internal degradation in a graded form.Such gradual effects,in turn,will change surface conditions through elastic constants and stiffness and more importantly the gradient of such properties across the thickness with certain depth.Now we study the thickness-shear vibrations of functionally graded material plates with properties of the popular AT-cut quartz crystal varying across the thickness in a general pattern represented by both sine and cosine components of the thickness.The vibration solutions are obtained through the Fourier expansion of the plate deformation.
