Improving interfacial bonding and alloying design are effective strategies for enhancing mechanical properties of particle-reinforced steel matrix composites(SMCs).This study prepared SMCs with uniformly distributed T...Improving interfacial bonding and alloying design are effective strategies for enhancing mechanical properties of particle-reinforced steel matrix composites(SMCs).This study prepared SMCs with uniformly distributed TiC_(P)in matrix using master alloying method.The TiC(002)/Fe(011)interface model was established based on the orientation relationship of(011)_(Fe)//(002)_(TiC),and[100]_(Fe)//[100]_(TiC).The effects of single and co-doping of alloying elements(Mn,Cr,Mo,Ni,Cu and Si)on the interface bonding behavior of TiC/Fe in composites were investigated in conjunction with first principles.The results demonstrate that the interface between TiC and matrix is continuous and stable.Compared to the undoped TiC/Fe interface,single-doping Mn,Cr,and Mo can improve the stability of TiC/Fe interface and enhance tensile strength.Conversely,single-doping with Ni,Cu,and Si reduced the interface stability and marginally reduces tensile strength.Relative to the undoped and singly Ni-doped TiC/Fe interfaces,the co-doping Ni-Mo boosts binding energy and separation work at the TiC/Fe interface,which is conducive to the interface bonding between TiC_(P)and matrix,and thus improves the mechanical properties of composites.Thus,in the alloying design of TiC particle reinforced low-alloy SMCs,incorporating Mn,Cr,Mo,and Ni into matrix can enhance the overall mechanical properties of composites.展开更多
Interface debonding between particle and matrix in composite propellant influences its macroscopic mechanical properties greatly. For this, the laws of interface cohesive damage and failure were analyzed. Then, its mi...Interface debonding between particle and matrix in composite propellant influences its macroscopic mechanical properties greatly. For this, the laws of interface cohesive damage and failure were analyzed. Then, its microscopic computational model was established. The interface mechanical response was modeled by the bilinear cohesive zone model. The effects of interface properties and particle sizes on the macroscopic mechanical behavior were investigated. Numerical simulation of debonding damage evolution of composite propellant under finite deformation was carried out. The debonding damage nucleation, propagation mechanism and non-uniform distribution of microscopic stress-strain fields were discussed. The results show that the finite element simulation method based on microstructure model can effectively predict the trend of macroscopic mechanical behavior and particle/matrix debonding evolution process. It can be used for damage simulation and failure assessment of composite propellants.展开更多
The damage of the self-compacting concrete in CRTSⅢslab ballastless track on bridge will lead to a partial void of the track slab,which will affect the comfort and safety of the train and the durability of the track ...The damage of the self-compacting concrete in CRTSⅢslab ballastless track on bridge will lead to a partial void of the track slab,which will affect the comfort and safety of the train and the durability of the track slab and bridge structure.In order to study the impact of the interface crack on the dynamic response of CRTSⅢballastless track system on bridge,based on the principle of multi-body dynamics theory and ANSYS+SIMPACK co-simulation,the spatial model of vehicle-track-bridge integration considering the longitudinal stiffness of supports,the track structure and interlayer contact characteristics were established.The dynamic characteristics of the system under different conditions of the width,length and position of the interface crack were analysed,and the limited values of the length and width of the cracks at the track slab edge were proposed.The results show that when the self-compacting concrete does not completely void along the transverse direction of the track slab,the crack has little effect on the dynamic characteristics of the vehicle-track-bridge system.However,when the self-compacting concrete is completely hollowed out along the transverse direction of the track slab,the dynamic amplitudes of the system increase.When the crack length is 1.6 m,the wheel load reduction rate reaches 0.769,which exceeds the limit value and threatens the safety of train operation.The vertical acceleration of the track slab increases by 250.1%,which affects the service life of the track system under the train speed of 200 km/h.展开更多
The Cr-plated coating inside a gun barrel can effectively improve the barrel’s erosion resistance and thus increase the service life.However,due to the cyclic thermal load caused by high-temperature gunpowder,micro-e...The Cr-plated coating inside a gun barrel can effectively improve the barrel’s erosion resistance and thus increase the service life.However,due to the cyclic thermal load caused by high-temperature gunpowder,micro-element damage tends to occur within the Cr coating/steel substrate interface,leading to a gradual deterioration in macro-mechanical properties for the material in the related region.In order to mimic this cyclic thermal load and,thereby,study the thermal erosion behavior of the Cr coating on the barrel’s inner wall,a laser emitter is utilized in the current study.With the help of in-situ tensile test and finite element simulation results,a shear stress distribution law of the Cr coating/steel substrate and a change law of the interface ultimate shear strength are identified.Studies have shown that the Cr coating/steel substrate interface’s ultimate shear strength has a significant weakening effect due to increasing temperature.In this study,the interfacial ultimate shear strength decreases from 2.57 GPa(no erosion)to 1.02 GPa(laser power is 160 W).The data from this experiment is employed to establish a Cr coating/steel substrate interface shear damage model.And this model is used to predict the flaking process of Cr coating by finite element method.The simulation results show that the increase of coating crack spacing and coating thickness will increase the service life of gun barrel.展开更多
The characteristics of a disturbed soil-structure interface were studied based on the variation regularities of the disturbed soil within its mining subsidence area using direct shear tests.The effects of the initial ...The characteristics of a disturbed soil-structure interface were studied based on the variation regularities of the disturbed soil within its mining subsidence area using direct shear tests.The effects of the initial moisture content on the shear strength parameters of the soil-structure interfaces were analyzed.The results indicate that the cohesion of the interface initially increased and then decreased as the initial moisture content increased.In addition,the friction angle of the interface decreased as the initial moisture content increased.A constitutive model of the disturbed soil-structure interface,a rigid-plastic model based on the initial void ratio and saturability(VSRP) model,was established based on the results.In order to validate this model,a finite element analysis of DRS-1 direct shear tests was conducted.The finite element model calculations coincided with the results of the DRS-1 direct shear tests.The proposed model also reflected the nonlinear features of the soil-structure interface.展开更多
The formation and the growth of Cu-Sn intermetallic compound (IMC) layer at the interface between Sn-3.0Ag-0.5Cu-xCe solder and Cu substrate during soldering and aging were studied. The results show that Cu6Sn5 IMC is...The formation and the growth of Cu-Sn intermetallic compound (IMC) layer at the interface between Sn-3.0Ag-0.5Cu-xCe solder and Cu substrate during soldering and aging were studied. The results show that Cu6Sn5 IMC is observed at the interface between solder and Cu substrate in all conditions. After aging for 120 h,the Cu3Sn IMC is then obtained. With increasing aging time,the scalloped Cu6Sn5 structure changes to a plate structure. The Cu3Sn film always forms with a relatively planar interface. By adding a small amount of the rare earth element Ce (only 0.1%,mass fraction) into the Sn-3.0Ag-0.5Cu solder alloy,the growth rate of the Cu-Sn IMC at the interface of solder alloy system is decreased. When the time exponent is approximately 0.5,the growth of the IMC layer is mainly controlled by a diffusion over the studied time range.展开更多
岩石-混凝土界面是工程结构的薄弱环节,对结构整体的强度和稳定性有重要影响。为反映岩-混界面天然粗糙状态,基于内聚力模型(cohesive zone model,简称CZM),建立了具有随机生成粗糙界面的岩石-混凝土复合巴西圆盘试件数值模型,通过不同...岩石-混凝土界面是工程结构的薄弱环节,对结构整体的强度和稳定性有重要影响。为反映岩-混界面天然粗糙状态,基于内聚力模型(cohesive zone model,简称CZM),建立了具有随机生成粗糙界面的岩石-混凝土复合巴西圆盘试件数值模型,通过不同加载角度下的巴西劈裂物理试验验证了该方法的可靠性,并探究了界面粗糙度、加载角度对试件峰值荷载和破坏特征的影响。结果表明:不同加载角度下,试件存在3种典型破坏模式:界面黏结破坏、复合破坏、双材料拉伸开裂破坏;加载角度对试件力学行为的影响以70°为界,加载角度小于70°时影响显著,大于70°后影响不显著;界面粗糙度的影响随加载角度的不同有较大差异,当加载角度在15°~65°范围内,提高界面粗糙度可显著提高试件峰值荷载,增强岩-混结构的承载能力;界面处应力状态的差异决定了试件破坏模式的不同,但粗糙的界面可以增强混凝土与岩石之间的黏结和互锁效应,对试件破坏模式产生影响。研究结果将加深对岩石-混凝土界面破坏机制的认识,对工程建设具有指导意义。展开更多
基金Project supported by the Special Funding Support for the Development of 1500 Meter Subsea Christmas Tree and Control System,China。
文摘Improving interfacial bonding and alloying design are effective strategies for enhancing mechanical properties of particle-reinforced steel matrix composites(SMCs).This study prepared SMCs with uniformly distributed TiC_(P)in matrix using master alloying method.The TiC(002)/Fe(011)interface model was established based on the orientation relationship of(011)_(Fe)//(002)_(TiC),and[100]_(Fe)//[100]_(TiC).The effects of single and co-doping of alloying elements(Mn,Cr,Mo,Ni,Cu and Si)on the interface bonding behavior of TiC/Fe in composites were investigated in conjunction with first principles.The results demonstrate that the interface between TiC and matrix is continuous and stable.Compared to the undoped TiC/Fe interface,single-doping Mn,Cr,and Mo can improve the stability of TiC/Fe interface and enhance tensile strength.Conversely,single-doping with Ni,Cu,and Si reduced the interface stability and marginally reduces tensile strength.Relative to the undoped and singly Ni-doped TiC/Fe interfaces,the co-doping Ni-Mo boosts binding energy and separation work at the TiC/Fe interface,which is conducive to the interface bonding between TiC_(P)and matrix,and thus improves the mechanical properties of composites.Thus,in the alloying design of TiC particle reinforced low-alloy SMCs,incorporating Mn,Cr,Mo,and Ni into matrix can enhance the overall mechanical properties of composites.
基金Sponsored by the General Armament Department Advanced Research Project (20101019)
文摘Interface debonding between particle and matrix in composite propellant influences its macroscopic mechanical properties greatly. For this, the laws of interface cohesive damage and failure were analyzed. Then, its microscopic computational model was established. The interface mechanical response was modeled by the bilinear cohesive zone model. The effects of interface properties and particle sizes on the macroscopic mechanical behavior were investigated. Numerical simulation of debonding damage evolution of composite propellant under finite deformation was carried out. The debonding damage nucleation, propagation mechanism and non-uniform distribution of microscopic stress-strain fields were discussed. The results show that the finite element simulation method based on microstructure model can effectively predict the trend of macroscopic mechanical behavior and particle/matrix debonding evolution process. It can be used for damage simulation and failure assessment of composite propellants.
基金Project(2017YFB1201204)supported by National Key R&D Program of China。
文摘The damage of the self-compacting concrete in CRTSⅢslab ballastless track on bridge will lead to a partial void of the track slab,which will affect the comfort and safety of the train and the durability of the track slab and bridge structure.In order to study the impact of the interface crack on the dynamic response of CRTSⅢballastless track system on bridge,based on the principle of multi-body dynamics theory and ANSYS+SIMPACK co-simulation,the spatial model of vehicle-track-bridge integration considering the longitudinal stiffness of supports,the track structure and interlayer contact characteristics were established.The dynamic characteristics of the system under different conditions of the width,length and position of the interface crack were analysed,and the limited values of the length and width of the cracks at the track slab edge were proposed.The results show that when the self-compacting concrete does not completely void along the transverse direction of the track slab,the crack has little effect on the dynamic characteristics of the vehicle-track-bridge system.However,when the self-compacting concrete is completely hollowed out along the transverse direction of the track slab,the dynamic amplitudes of the system increase.When the crack length is 1.6 m,the wheel load reduction rate reaches 0.769,which exceeds the limit value and threatens the safety of train operation.The vertical acceleration of the track slab increases by 250.1%,which affects the service life of the track system under the train speed of 200 km/h.
文摘The Cr-plated coating inside a gun barrel can effectively improve the barrel’s erosion resistance and thus increase the service life.However,due to the cyclic thermal load caused by high-temperature gunpowder,micro-element damage tends to occur within the Cr coating/steel substrate interface,leading to a gradual deterioration in macro-mechanical properties for the material in the related region.In order to mimic this cyclic thermal load and,thereby,study the thermal erosion behavior of the Cr coating on the barrel’s inner wall,a laser emitter is utilized in the current study.With the help of in-situ tensile test and finite element simulation results,a shear stress distribution law of the Cr coating/steel substrate and a change law of the interface ultimate shear strength are identified.Studies have shown that the Cr coating/steel substrate interface’s ultimate shear strength has a significant weakening effect due to increasing temperature.In this study,the interfacial ultimate shear strength decreases from 2.57 GPa(no erosion)to 1.02 GPa(laser power is 160 W).The data from this experiment is employed to establish a Cr coating/steel substrate interface shear damage model.And this model is used to predict the flaking process of Cr coating by finite element method.The simulation results show that the increase of coating crack spacing and coating thickness will increase the service life of gun barrel.
基金Project(51274192)supported by National Natural Science Foundation of China
文摘The characteristics of a disturbed soil-structure interface were studied based on the variation regularities of the disturbed soil within its mining subsidence area using direct shear tests.The effects of the initial moisture content on the shear strength parameters of the soil-structure interfaces were analyzed.The results indicate that the cohesion of the interface initially increased and then decreased as the initial moisture content increased.In addition,the friction angle of the interface decreased as the initial moisture content increased.A constitutive model of the disturbed soil-structure interface,a rigid-plastic model based on the initial void ratio and saturability(VSRP) model,was established based on the results.In order to validate this model,a finite element analysis of DRS-1 direct shear tests was conducted.The finite element model calculations coincided with the results of the DRS-1 direct shear tests.The proposed model also reflected the nonlinear features of the soil-structure interface.
基金Project(06GK2002) supported by the Major Project of Hunan Provincial Science and Technology Development Strategy
文摘The formation and the growth of Cu-Sn intermetallic compound (IMC) layer at the interface between Sn-3.0Ag-0.5Cu-xCe solder and Cu substrate during soldering and aging were studied. The results show that Cu6Sn5 IMC is observed at the interface between solder and Cu substrate in all conditions. After aging for 120 h,the Cu3Sn IMC is then obtained. With increasing aging time,the scalloped Cu6Sn5 structure changes to a plate structure. The Cu3Sn film always forms with a relatively planar interface. By adding a small amount of the rare earth element Ce (only 0.1%,mass fraction) into the Sn-3.0Ag-0.5Cu solder alloy,the growth rate of the Cu-Sn IMC at the interface of solder alloy system is decreased. When the time exponent is approximately 0.5,the growth of the IMC layer is mainly controlled by a diffusion over the studied time range.
文摘岩石-混凝土界面是工程结构的薄弱环节,对结构整体的强度和稳定性有重要影响。为反映岩-混界面天然粗糙状态,基于内聚力模型(cohesive zone model,简称CZM),建立了具有随机生成粗糙界面的岩石-混凝土复合巴西圆盘试件数值模型,通过不同加载角度下的巴西劈裂物理试验验证了该方法的可靠性,并探究了界面粗糙度、加载角度对试件峰值荷载和破坏特征的影响。结果表明:不同加载角度下,试件存在3种典型破坏模式:界面黏结破坏、复合破坏、双材料拉伸开裂破坏;加载角度对试件力学行为的影响以70°为界,加载角度小于70°时影响显著,大于70°后影响不显著;界面粗糙度的影响随加载角度的不同有较大差异,当加载角度在15°~65°范围内,提高界面粗糙度可显著提高试件峰值荷载,增强岩-混结构的承载能力;界面处应力状态的差异决定了试件破坏模式的不同,但粗糙的界面可以增强混凝土与岩石之间的黏结和互锁效应,对试件破坏模式产生影响。研究结果将加深对岩石-混凝土界面破坏机制的认识,对工程建设具有指导意义。
