A thermal-solid-liquid complex operational environment induces structural interface developing a typical coupling sliding/impact wear behavior.It results in contact damage until systems fail,which may cause significan...A thermal-solid-liquid complex operational environment induces structural interface developing a typical coupling sliding/impact wear behavior.It results in contact damage until systems fail,which may cause significant economic losses and catastrophic consequences.The key point of solving this problem is to reveal the coupling damage mechanism of the sliding/impact behavior in typical systems and life characterization under a complicate evolving environment.This has been a hot topic in the area of mechanical reliability.The main work in this paper can be concluded as follows.Firstly,the main industries in which the"sliding/impact behavior"takes place have been introduced.Then,existing studies on the wear mechanism and degree analysis are presented,which includes surface morphology analysis,wear debris analysis,and wear degree measurement.Meanwhile,existing problems in theoretical modeling and experiments in current research are summarized,so as to point out a bright direction for future research on wear prediction.They include interface contact modeling,mathematic coupling mechanism modeling,wear equation establishment,and wear life characterization,which can provide some new ideas for improving the existing studies on the sliding/impact wear behavior.展开更多
This work addresses the critical issue of current density distribution in the sliding electrical contact interface based on electromechanical coupling, which is essential for minimizing damage and enhancing performanc...This work addresses the critical issue of current density distribution in the sliding electrical contact interface based on electromechanical coupling, which is essential for minimizing damage and enhancing performance. Using electromechanical coupling analysis and finite element analysis (FEA), the effects of initial contact pressure, pulse current input, and armature speed on current density are examined. Key findings indicate that optimizing the convex rail and armature structures significantly reduces peak current density, improving uniformity and reducing damage. These optimizations enhance the efficiency, accuracy, and service life of sliding electrical contact interfaces, providing a theoretical foundation for designing more durable and efficient high-current-density applications.展开更多
The pre-sliding regime is typically neglected in the dynamic modelling of mechanical systems. However, the change in contact state caused by static friction may decrease positional accuracy and control precision. To i...The pre-sliding regime is typically neglected in the dynamic modelling of mechanical systems. However, the change in contact state caused by static friction may decrease positional accuracy and control precision. To investigate the relationship between contact status and contact force in pre-sliding friction, an optical experimental method is presented in this paper.With this method, the real contact state at the interface of a transparent material can be observed based on the total reflection principle of light by using an image processing technique. A novel setup, which includes a pair of rectangular trapezoidal blocks, is proposed to solve the challenging issue of accurately applying different tangential and normal forces to the contact interface. The improved Otsu＇s method is used for measurement. Through an experimental study performed on polymethyl methacrylate（PMMA）, the quantity of contact asperities is proven to be the dominant factor that affects the real contact area. The relationship between the real contact area and the contact force in the pre-sliding regime is studied, and the distribution of static friction at the contact interface is qualitatively discussed. New phenomena in which the real contact area expands along with increasing static friction are identified. The aforementioned relationship is approximately linear at the contact interface under a constant normal pressure, and the distribution of friction stress decreases from the leading edge to the trailing edge.展开更多
Split Hopkinson pressure bar (SHPB) has become a frequently used technique to measure the uniaxial compressive stress-strain relation of various engineering materials at high strain-rates. The accuracy of an SHPB test...Split Hopkinson pressure bar (SHPB) has become a frequently used technique to measure the uniaxial compressive stress-strain relation of various engineering materials at high strain-rates. The accuracy of an SHPB test is based on the assumption of uniaxial and uniform stress distribution within the specimen, which, however, is not always satisfied in an actual SHPB test due to the existence of some unavoidable negative factors, e.g., interface friction constrains. Kinetic interface friction tests based on a simple device for engineering materials testing on SHPB tests are performed. A kinetic interface friction model is proposed and validated by implementing it into a numerical model. It shows that the proposed simple device is sufficient to obtain kinetic interface friction results for common SHPB tests. The kinetic friction model should be used instead of the frequently used constant friction model for more accurate numerical simulation of SHPB tests.展开更多
基金supported by the National Natural Science Foundation of China(No.51675025).
文摘A thermal-solid-liquid complex operational environment induces structural interface developing a typical coupling sliding/impact wear behavior.It results in contact damage until systems fail,which may cause significant economic losses and catastrophic consequences.The key point of solving this problem is to reveal the coupling damage mechanism of the sliding/impact behavior in typical systems and life characterization under a complicate evolving environment.This has been a hot topic in the area of mechanical reliability.The main work in this paper can be concluded as follows.Firstly,the main industries in which the"sliding/impact behavior"takes place have been introduced.Then,existing studies on the wear mechanism and degree analysis are presented,which includes surface morphology analysis,wear debris analysis,and wear degree measurement.Meanwhile,existing problems in theoretical modeling and experiments in current research are summarized,so as to point out a bright direction for future research on wear prediction.They include interface contact modeling,mathematic coupling mechanism modeling,wear equation establishment,and wear life characterization,which can provide some new ideas for improving the existing studies on the sliding/impact wear behavior.
文摘This work addresses the critical issue of current density distribution in the sliding electrical contact interface based on electromechanical coupling, which is essential for minimizing damage and enhancing performance. Using electromechanical coupling analysis and finite element analysis (FEA), the effects of initial contact pressure, pulse current input, and armature speed on current density are examined. Key findings indicate that optimizing the convex rail and armature structures significantly reduces peak current density, improving uniformity and reducing damage. These optimizations enhance the efficiency, accuracy, and service life of sliding electrical contact interfaces, providing a theoretical foundation for designing more durable and efficient high-current-density applications.
基金Project supported by the National Natural Science Foundation of China(Grant No.11272171)the Natural Science Foundation of Beijing City,China(Contract No.3172017)the Education Ministry Doctoral Fund of China(Grant No.20120002110070)
文摘The pre-sliding regime is typically neglected in the dynamic modelling of mechanical systems. However, the change in contact state caused by static friction may decrease positional accuracy and control precision. To investigate the relationship between contact status and contact force in pre-sliding friction, an optical experimental method is presented in this paper.With this method, the real contact state at the interface of a transparent material can be observed based on the total reflection principle of light by using an image processing technique. A novel setup, which includes a pair of rectangular trapezoidal blocks, is proposed to solve the challenging issue of accurately applying different tangential and normal forces to the contact interface. The improved Otsu＇s method is used for measurement. Through an experimental study performed on polymethyl methacrylate（PMMA）, the quantity of contact asperities is proven to be the dominant factor that affects the real contact area. The relationship between the real contact area and the contact force in the pre-sliding regime is studied, and the distribution of static friction at the contact interface is qualitatively discussed. New phenomena in which the real contact area expands along with increasing static friction are identified. The aforementioned relationship is approximately linear at the contact interface under a constant normal pressure, and the distribution of friction stress decreases from the leading edge to the trailing edge.
文摘Split Hopkinson pressure bar (SHPB) has become a frequently used technique to measure the uniaxial compressive stress-strain relation of various engineering materials at high strain-rates. The accuracy of an SHPB test is based on the assumption of uniaxial and uniform stress distribution within the specimen, which, however, is not always satisfied in an actual SHPB test due to the existence of some unavoidable negative factors, e.g., interface friction constrains. Kinetic interface friction tests based on a simple device for engineering materials testing on SHPB tests are performed. A kinetic interface friction model is proposed and validated by implementing it into a numerical model. It shows that the proposed simple device is sufficient to obtain kinetic interface friction results for common SHPB tests. The kinetic friction model should be used instead of the frequently used constant friction model for more accurate numerical simulation of SHPB tests.
