2000 Vol.13(1)
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2000, 14(1).
Abstract:
The finite segment modelling for the flexible beam-formed structural elements is presented, in which the discretization views of the finite segment method and the difference from the finite element method are introduced. In terms of the nodal model, the joint properties are described easily by the model of the finite segment method, and according to the element properties,the assumption of the small strain is only met in the finite segment method,I.e.,the geometric nonlinear deformation of the flexible bodies is allowble.Consequently, the finite segment method is very suited to the flexible multibody structure.The finite segment model is used and the arc differentiation is adopted for the differential beam segments. Thestiffness equation is derived by the use of the principle of virtual work. The new modelling method shows its normalization,clear physical and geometric meanings and simple computational process.
The finite segment modelling for the flexible beam-formed structural elements is presented, in which the discretization views of the finite segment method and the difference from the finite element method are introduced. In terms of the nodal model, the joint properties are described easily by the model of the finite segment method, and according to the element properties,the assumption of the small strain is only met in the finite segment method,I.e.,the geometric nonlinear deformation of the flexible bodies is allowble.Consequently, the finite segment method is very suited to the flexible multibody structure.The finite segment model is used and the arc differentiation is adopted for the differential beam segments. Thestiffness equation is derived by the use of the principle of virtual work. The new modelling method shows its normalization,clear physical and geometric meanings and simple computational process.
2000, 14(1).
Abstract:
Incorporated with constitutive relationship established by artificial neural networks(ANN),a coupled thermoviscoplastic finite element procedure is developed for predictiong the microstructure evolution in the hot forging process,considering the factors such as dynamic recrystallization,static recrystallization and grain growth etc.This software system is applied to predict the distribution of the grain size over the cross-section of stigmata,which is found to be in good agreement with the experimental results.The software can provide a fundament for optimizing technological parameters.
Incorporated with constitutive relationship established by artificial neural networks(ANN),a coupled thermoviscoplastic finite element procedure is developed for predictiong the microstructure evolution in the hot forging process,considering the factors such as dynamic recrystallization,static recrystallization and grain growth etc.This software system is applied to predict the distribution of the grain size over the cross-section of stigmata,which is found to be in good agreement with the experimental results.The software can provide a fundament for optimizing technological parameters.
2000, 14(1).
Abstract:
The linear isothermo-viscoelastic constitutive equation is established according to the principle of viscoelastic mechanics.Given the boundary conditions of the temperature field,the linear thermo-viscoelastic costitutive equation is established acording to the analysis of the thermorheologically simple. The stress analysis model is constructed on the base of some reasonable hypotheses which consider the restraint conditions of mold and the characteristics of injection molding in the post-filling stage.The mathematical model is calculated by the finite difference method. The results can help to predict the warpage of plastic products.
The linear isothermo-viscoelastic constitutive equation is established according to the principle of viscoelastic mechanics.Given the boundary conditions of the temperature field,the linear thermo-viscoelastic costitutive equation is established acording to the analysis of the thermorheologically simple. The stress analysis model is constructed on the base of some reasonable hypotheses which consider the restraint conditions of mold and the characteristics of injection molding in the post-filling stage.The mathematical model is calculated by the finite difference method. The results can help to predict the warpage of plastic products.
2000, 14(1).
Abstract:
A new approach to model viscosity in the conservation of momentum equations is presented and discussed. Coefficient of viscosity is modeled in such a way that it reaches asymptotically to infinity at the solid boundary but still yields a finite value for the shear stress at the solid wall. Basic objective of this research is to show that certain combinations of higher order normal velocity gradients become zero at the solid boundary .Modified solution for the Couette flow and Poiseuille flow between two parallel plates are obtained by modeling the coefficient of viscosity in a novel way.Also,viscous drag computed by our model is expected to yield higher values than the values predicted by the existing models,which matches closely to the experimental data.
A new approach to model viscosity in the conservation of momentum equations is presented and discussed. Coefficient of viscosity is modeled in such a way that it reaches asymptotically to infinity at the solid boundary but still yields a finite value for the shear stress at the solid wall. Basic objective of this research is to show that certain combinations of higher order normal velocity gradients become zero at the solid boundary .Modified solution for the Couette flow and Poiseuille flow between two parallel plates are obtained by modeling the coefficient of viscosity in a novel way.Also,viscous drag computed by our model is expected to yield higher values than the values predicted by the existing models,which matches closely to the experimental data.
2000, 14(1).
Abstract:
A new algorithm called homotopy iteration method based on the homotopy function is studied and improved. By the improved homotopy iteration method,polynomial systems with high order and deficient can be solved fast and efficiently comparing to the original homotopy iteration method. Numerical examples for the ninepoint path synthesis of four-bar linkages show the advantages and efficiency of the improved homotopy iteration method.
A new algorithm called homotopy iteration method based on the homotopy function is studied and improved. By the improved homotopy iteration method,polynomial systems with high order and deficient can be solved fast and efficiently comparing to the original homotopy iteration method. Numerical examples for the ninepoint path synthesis of four-bar linkages show the advantages and efficiency of the improved homotopy iteration method.
2000, 14(1).
Abstract:
The neuro-fuzzy network(NFN)is used to model the rules and experience of the process planner.NFN is to select the manufacturing operations sequences for the part features.A detailed description of the NFN system development is given.The rule structure utilizes sigmoid functions to fuzzify the inputs,multiplication to combline the if part of the rules and summation to integrate the fired rules. Expert knowledge from previous process plans is used in determining the initial network structure and parameters of the membership functions. A back-propagation(BP)training algorithm was developed to fine tune the knowledge to company standards using the input-output data from executions of previous plans.The method is illustrated by an industrial example.
The neuro-fuzzy network(NFN)is used to model the rules and experience of the process planner.NFN is to select the manufacturing operations sequences for the part features.A detailed description of the NFN system development is given.The rule structure utilizes sigmoid functions to fuzzify the inputs,multiplication to combline the if part of the rules and summation to integrate the fired rules. Expert knowledge from previous process plans is used in determining the initial network structure and parameters of the membership functions. A back-propagation(BP)training algorithm was developed to fine tune the knowledge to company standards using the input-output data from executions of previous plans.The method is illustrated by an industrial example.
2000, 14(1).
Abstract:
A technology of two-coordinate dual-servo(TCDS)is proposed.Using this technology which is based on error compensation, workpieces of higher contour accuracy could be turned on ultra-precision machine tool with poor dynamic performances. The principle, constitute and operation of a TCDS system are described. Mathematical proof and experiments are achieved in addition.
A technology of two-coordinate dual-servo(TCDS)is proposed.Using this technology which is based on error compensation, workpieces of higher contour accuracy could be turned on ultra-precision machine tool with poor dynamic performances. The principle, constitute and operation of a TCDS system are described. Mathematical proof and experiments are achieved in addition.
2000, 14(1).
Abstract:
The research on the driving principle and economization of energy of electro-hydraulic hammer is discussed.By means of the balance chart of energy,the method and formulas to calculate every level efficiency and the total efficiency of steam drived hammer are formed.With the aid of actual data of plants,the actual efficiency of steam drived hammer is got.The working principle and the driving system of electro-hydraulic hammer are introduced.The procedure of energy transfer of this hammer is analyzed.The utilization ratio of energy of this type of hammer is got.It is shown that the efficiency of elector-hydraulic hammer is 7 times as much as that of steam drived hammer.
The research on the driving principle and economization of energy of electro-hydraulic hammer is discussed.By means of the balance chart of energy,the method and formulas to calculate every level efficiency and the total efficiency of steam drived hammer are formed.With the aid of actual data of plants,the actual efficiency of steam drived hammer is got.The working principle and the driving system of electro-hydraulic hammer are introduced.The procedure of energy transfer of this hammer is analyzed.The utilization ratio of energy of this type of hammer is got.It is shown that the efficiency of elector-hydraulic hammer is 7 times as much as that of steam drived hammer.
2000, 14(1).
Abstract:
According to spatial conjugate principle and theory of elastic conatct,a method to pre-control transmission properties and contact mark of point meshing gear is presented,while the deformation of tooth surface is under consideration.A new appuoach to improve the quality of spiral bevel gear is illustrated emphatically.
According to spatial conjugate principle and theory of elastic conatct,a method to pre-control transmission properties and contact mark of point meshing gear is presented,while the deformation of tooth surface is under consideration.A new appuoach to improve the quality of spiral bevel gear is illustrated emphatically.
2000, 14(1).
Abstract:
In order to reduce time and cost in engineering design,such as gate design,integral field knowledge must be obtained effciently. After studying ID3 and its improved methods ,a new algorithm(Fuzzy ID3) and its main concept are presented to overcome some disadvantage in classical ID3 algorithms.In its application of gate design,fuzzy knowledge gotten by the new algorithm is more efficient than the knowledge by other ID3 algorithms,the set of fuzzy knowledge is much smaller than that of knowledge by classical ID3 algorithms.On the other hand,fuzzy knowledge represents field data more naturally to the way of human thinking and more robust in tolerating imprecise,conflicting and missing information.
In order to reduce time and cost in engineering design,such as gate design,integral field knowledge must be obtained effciently. After studying ID3 and its improved methods ,a new algorithm(Fuzzy ID3) and its main concept are presented to overcome some disadvantage in classical ID3 algorithms.In its application of gate design,fuzzy knowledge gotten by the new algorithm is more efficient than the knowledge by other ID3 algorithms,the set of fuzzy knowledge is much smaller than that of knowledge by classical ID3 algorithms.On the other hand,fuzzy knowledge represents field data more naturally to the way of human thinking and more robust in tolerating imprecise,conflicting and missing information.
2000, 14(1).
Abstract:
Based on the kinematic relationship of the drill,drill point and workpiece and the coordinate systems founded,the mathematical models of the drill point wandering motion for the drill initial penetration,I.e.the formulate for the drill point center locus,hole shape and cutting edge locus,are established.According to these formulae the hole shape to be made is simulated and analyzed.It is verified that the bending chatter of the drill during the drill penetrating is the main cause to form a polygon like hole.
Based on the kinematic relationship of the drill,drill point and workpiece and the coordinate systems founded,the mathematical models of the drill point wandering motion for the drill initial penetration,I.e.the formulate for the drill point center locus,hole shape and cutting edge locus,are established.According to these formulae the hole shape to be made is simulated and analyzed.It is verified that the bending chatter of the drill during the drill penetrating is the main cause to form a polygon like hole.
2000, 14(1).
Abstract:
Traditional methods for performance prediction of a turbomachinery are usually based on certain computations from a set of data obtained in limited experiment measurements of the machine,or the machinemodels.Since the computational（mathematical)models used in such performance prediction are often crude,most of the predicted results are only correct in very small ranges around the known data points.Beyond the limited ranges,the accuracy of the resultant predictions decrease abruptly.Therefore,an alternative approah,neural network technique,is studied for performance prediction of turbomachinery.The new approach has been applied to two typical performance prediction cases to verify its feasibility and reliability
Traditional methods for performance prediction of a turbomachinery are usually based on certain computations from a set of data obtained in limited experiment measurements of the machine,or the machinemodels.Since the computational（mathematical)models used in such performance prediction are often crude,most of the predicted results are only correct in very small ranges around the known data points.Beyond the limited ranges,the accuracy of the resultant predictions decrease abruptly.Therefore,an alternative approah,neural network technique,is studied for performance prediction of turbomachinery.The new approach has been applied to two typical performance prediction cases to verify its feasibility and reliability
2000, 14(1).
Abstract:
The deposition mechanism of diamond film on cutting tools and the state of the interface between film and substrate are studied theoretically and experimentally.Mehthods for controlling diamond crystalline state and improving adhesion of diamond films to substrates are proposed to improve the quality of diamond-coated tools.Experiments are performed by cutting Al-Si18% alloy and SiCp/Al composite with diamond coated tool. The results indicate that the life of coated tools is 90 times higher than that of non-coated tools. Wear mechanism of diamond-coated tools is also studied.
The deposition mechanism of diamond film on cutting tools and the state of the interface between film and substrate are studied theoretically and experimentally.Mehthods for controlling diamond crystalline state and improving adhesion of diamond films to substrates are proposed to improve the quality of diamond-coated tools.Experiments are performed by cutting Al-Si18% alloy and SiCp/Al composite with diamond coated tool. The results indicate that the life of coated tools is 90 times higher than that of non-coated tools. Wear mechanism of diamond-coated tools is also studied.
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