With the development of science and technology, the ultra-precision manufacturing of the brittle and hard materials with superior quality have become a new attractive subject. Brittle materials (such as engineering ce...With the development of science and technology, the ultra-precision manufacturing of the brittle and hard materials with superior quality have become a new attractive subject. Brittle materials (such as engineering ceramics, optical glass, semiconductor and so on) are widely used in electronics, optics, aeronautics and other high technology fields, so there are important theory significance and practical value to systematically study its machining mechanism and technology. Single crystal silicon is one of the typical brittle materials. Single crystal silicon wafer is a basic component of large and ultralarge integrated the circuit, its surface roughness and flatness are the key factor of improving its integration. With the successfully producing of the large diameter single crystal silicon wafer, its manufacturing technology became attractive subject again. This paper carries out computer simulation of nanometer cutting on single crystal silicon. Molecular Dynamics method which is different from continuous mechanics is employed to investigate the features of grinding energy dissipation, grinding force, stress state and grinding temperature, constructs the atom model of tool and work piece, and explains the microscale mechanism of material remove and surface generation of nanometer(subnanometer) manufacturing. This paper also investigates the variation of cutting force, thrust force, specific energy and surface deformation with different tool edge radius, different depth of cut.展开更多
A new precise actuator is proposed,which is ac-tuated by the impact force of an end-loaded piezoelectric bimorph cantilever,and bears two degrees of freedom for translation and rotation.The dynamic characteristics of ...A new precise actuator is proposed,which is ac-tuated by the impact force of an end-loaded piezoelectric bimorph cantilever,and bears two degrees of freedom for translation and rotation.The dynamic characteristics of the piezoelectric bimorph were analyzed by FEM,and are fur-ther proved by experimental tests.A new control system for the actuator was put forward and tested,which is called the fixed-frequency with adjustable voltage.In addition,the actuator’s performance of translation and rotation were both measured.The results demonstrate that the actuator is char-acterized by a simple structure,large movement range,strong driving ability and high positioning resolution.Its cost is estimated at only 1%of the traditional impact actuators.展开更多
Fused deposition modeling （FDM） is one of the most popuIar additive manufacturing technologies for various engineering applications. FDM process has been introduced commercially in early 1990s by Stratasys Inc., USA...Fused deposition modeling （FDM） is one of the most popuIar additive manufacturing technologies for various engineering applications. FDM process has been introduced commercially in early 1990s by Stratasys Inc., USA. The quality of FDM processed parts mainly depends on careful selection of process variables. Thus, identifica- tion of the FDM process parameters that significantly affect the quality of FDM processed parts is important. In recent years, researchers have explored a number of ways to improve the mechanical properties and part quality using various experimental design techniques and concepts. This article aims to review the research carried out so far in determining and optimizing the process parameters of the FDM process. Several statistical designs of experiments and optimization techniques used for the determination of optimum process parameters have been examined. The trends for future FDM research in this area are described.展开更多
文摘With the development of science and technology, the ultra-precision manufacturing of the brittle and hard materials with superior quality have become a new attractive subject. Brittle materials (such as engineering ceramics, optical glass, semiconductor and so on) are widely used in electronics, optics, aeronautics and other high technology fields, so there are important theory significance and practical value to systematically study its machining mechanism and technology. Single crystal silicon is one of the typical brittle materials. Single crystal silicon wafer is a basic component of large and ultralarge integrated the circuit, its surface roughness and flatness are the key factor of improving its integration. With the successfully producing of the large diameter single crystal silicon wafer, its manufacturing technology became attractive subject again. This paper carries out computer simulation of nanometer cutting on single crystal silicon. Molecular Dynamics method which is different from continuous mechanics is employed to investigate the features of grinding energy dissipation, grinding force, stress state and grinding temperature, constructs the atom model of tool and work piece, and explains the microscale mechanism of material remove and surface generation of nanometer(subnanometer) manufacturing. This paper also investigates the variation of cutting force, thrust force, specific energy and surface deformation with different tool edge radius, different depth of cut.
文摘A new precise actuator is proposed,which is ac-tuated by the impact force of an end-loaded piezoelectric bimorph cantilever,and bears two degrees of freedom for translation and rotation.The dynamic characteristics of the piezoelectric bimorph were analyzed by FEM,and are fur-ther proved by experimental tests.A new control system for the actuator was put forward and tested,which is called the fixed-frequency with adjustable voltage.In addition,the actuator’s performance of translation and rotation were both measured.The results demonstrate that the actuator is char-acterized by a simple structure,large movement range,strong driving ability and high positioning resolution.Its cost is estimated at only 1%of the traditional impact actuators.
文摘Fused deposition modeling （FDM） is one of the most popuIar additive manufacturing technologies for various engineering applications. FDM process has been introduced commercially in early 1990s by Stratasys Inc., USA. The quality of FDM processed parts mainly depends on careful selection of process variables. Thus, identifica- tion of the FDM process parameters that significantly affect the quality of FDM processed parts is important. In recent years, researchers have explored a number of ways to improve the mechanical properties and part quality using various experimental design techniques and concepts. This article aims to review the research carried out so far in determining and optimizing the process parameters of the FDM process. Several statistical designs of experiments and optimization techniques used for the determination of optimum process parameters have been examined. The trends for future FDM research in this area are described.
