1990 Vol.3(2)
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1990, 4(2).
Abstract:
A study of low-cylce fatigue behavior of 12CrMoV dual phase steel was carried out by experiment and finite element analysis. The low-cycle fatigue test under strain control with three different strain amplitudes for five kinds of specimens with different M(martensite) content was carried out on MTS-880. Some of the experimental results were analysed by finite element method. The influence of microstructures on low-cycle fatigue behavior in dual phase steel was discussed from the view of accumulative plastic strain.
A study of low-cylce fatigue behavior of 12CrMoV dual phase steel was carried out by experiment and finite element analysis. The low-cycle fatigue test under strain control with three different strain amplitudes for five kinds of specimens with different M(martensite) content was carried out on MTS-880. Some of the experimental results were analysed by finite element method. The influence of microstructures on low-cycle fatigue behavior in dual phase steel was discussed from the view of accumulative plastic strain.
1990, 4(2).
Abstract:
Based on the Kane's eqs, a new dynamical algorithm is presented. The algorithm is efficient in solving the dynamical problems of closed-chain manipulators, and characterized by a closed form. The computational equation of the dividing computational method for manipulator dynamics is derived too. A software package named DYNNS of computer generating numeric-symbolic robotic model is programmed based on the algorithm proposed. Numeric-symbolic dynamical equations of the main structure of the arc welding robot YG-1 are derived using the DYNNS.
Based on the Kane's eqs, a new dynamical algorithm is presented. The algorithm is efficient in solving the dynamical problems of closed-chain manipulators, and characterized by a closed form. The computational equation of the dividing computational method for manipulator dynamics is derived too. A software package named DYNNS of computer generating numeric-symbolic robotic model is programmed based on the algorithm proposed. Numeric-symbolic dynamical equations of the main structure of the arc welding robot YG-1 are derived using the DYNNS.
1990, 4(2).
Abstract:
Overall discussion of basic characteristics of fatigue process; irreversible damage process, stochastic and probabilistic character and field effect (size effect). Basic assumptions of PFDM (Probabilistic Fatigue Damage Mechanics); isotropy of material, homogeneous distribution of natural damage before loading, and evolution model of mechanical damage. Study of basic element (dxdydz) on its physical background and mechanism; form of damage parameters, damage equation, failure state equation, probabilistic expression of fatigue damage for constant amplitude loading. Using "Weakest Link Theory" of unequal strength the expression of fatigue probabilistic damage of definite field or structural component has been derived. Some examples are given in present paper, theoretical and experimental forms of distribution are compared.
Overall discussion of basic characteristics of fatigue process; irreversible damage process, stochastic and probabilistic character and field effect (size effect). Basic assumptions of PFDM (Probabilistic Fatigue Damage Mechanics); isotropy of material, homogeneous distribution of natural damage before loading, and evolution model of mechanical damage. Study of basic element (dxdydz) on its physical background and mechanism; form of damage parameters, damage equation, failure state equation, probabilistic expression of fatigue damage for constant amplitude loading. Using "Weakest Link Theory" of unequal strength the expression of fatigue probabilistic damage of definite field or structural component has been derived. Some examples are given in present paper, theoretical and experimental forms of distribution are compared.
1990, 4(2).
Abstract:
A low alloy ultra-high-strength steel was designed by using the valence electron structures, the kinetures, the kinetics of phase transformation and the morphology as well as the relation between strength and toughness of 30CrMnSiNi2A and Gc-4 steels. The new steel is 40CrMnSi2Ni2MoVCuA, which has both the hith toughness of 30CrMnSiNi2A and the ultra-high-strength of Gc-4, and its composition is similar to that of 300M alloy. Consequently, the nature of this work is to establish the valence electron structure and microscopically to design the composition of the American alloy 300M, which is a best low alloy ultra-high-strength steel.
A low alloy ultra-high-strength steel was designed by using the valence electron structures, the kinetures, the kinetics of phase transformation and the morphology as well as the relation between strength and toughness of 30CrMnSiNi2A and Gc-4 steels. The new steel is 40CrMnSi2Ni2MoVCuA, which has both the hith toughness of 30CrMnSiNi2A and the ultra-high-strength of Gc-4, and its composition is similar to that of 300M alloy. Consequently, the nature of this work is to establish the valence electron structure and microscopically to design the composition of the American alloy 300M, which is a best low alloy ultra-high-strength steel.
1990, 4(2).
Abstract:
A method to confine the model experiment with the practical measurement has been used to completely reveal the distributing rule of the dynamic stresses along the time and height coordinate in the hammer. A new theory has been put forward, viz, the hammer rod is subjected to both the tensile and compressive stresses with the same magnitude and frequency. Two high-peak stress zones have been found in the hammer rod, namely, the high-peak tensile stress zone and the high-peak compressive stress zone. The position of the former zone is agreeable with the statistical law. The formation mechanism and the affected factors have been analyzed by means of wave mechanics. Furthermore, the experiments about the effect of the wave resistance ratio on the load and stress transmissions have been performed, a new way has been pointed out from theory and practice for improving the design and use of the hammer rods and rod componenst of the forging and stamping equipment, and for prolonging their service life.
A method to confine the model experiment with the practical measurement has been used to completely reveal the distributing rule of the dynamic stresses along the time and height coordinate in the hammer. A new theory has been put forward, viz, the hammer rod is subjected to both the tensile and compressive stresses with the same magnitude and frequency. Two high-peak stress zones have been found in the hammer rod, namely, the high-peak tensile stress zone and the high-peak compressive stress zone. The position of the former zone is agreeable with the statistical law. The formation mechanism and the affected factors have been analyzed by means of wave mechanics. Furthermore, the experiments about the effect of the wave resistance ratio on the load and stress transmissions have been performed, a new way has been pointed out from theory and practice for improving the design and use of the hammer rods and rod componenst of the forging and stamping equipment, and for prolonging their service life.
1990, 4(2).
Abstract:
The rapid heating from room temperature to being melted and punctured in impure lead plates of different diameter and thickness, irradiated by laser beams at various power density, as to model the laser welding process, are studied experimentally and numerically. A method for predicting the temperature history is presented, which meets with success in transforming the complex heat transfer problem with movable solid-liquid phase boundary to one dealing the transient heat conduction with considerations of variable thermophysical properties. The experimental and numerical results are summarized and well discussed.
The rapid heating from room temperature to being melted and punctured in impure lead plates of different diameter and thickness, irradiated by laser beams at various power density, as to model the laser welding process, are studied experimentally and numerically. A method for predicting the temperature history is presented, which meets with success in transforming the complex heat transfer problem with movable solid-liquid phase boundary to one dealing the transient heat conduction with considerations of variable thermophysical properties. The experimental and numerical results are summarized and well discussed.
1990, 4(2).
Abstract:
The method of using an image analyser to display the growth kinetics of ferrite is proposed. The problem of three-dimensional growth is converted to two-dimensional, and the growth kinetics of ferrite is displayed on plane. Comparing the image of growth kinetics of ferrite with the true microstructure it is shown that the structure, morphology, distribution, size, colour and grey level are quite similar for both cases. The two-dimensional curve of growth kinetics of ferrite obtained by image analyser is corrected by three-dimensional curve from calculation using statistical mean radius of graphite spheres to make the two-dimensional image of growth kinetics of ferrite being in quantitative agreement with true process of three-dimensional growth kinetics of ferrite.
The method of using an image analyser to display the growth kinetics of ferrite is proposed. The problem of three-dimensional growth is converted to two-dimensional, and the growth kinetics of ferrite is displayed on plane. Comparing the image of growth kinetics of ferrite with the true microstructure it is shown that the structure, morphology, distribution, size, colour and grey level are quite similar for both cases. The two-dimensional curve of growth kinetics of ferrite obtained by image analyser is corrected by three-dimensional curve from calculation using statistical mean radius of graphite spheres to make the two-dimensional image of growth kinetics of ferrite being in quantitative agreement with true process of three-dimensional growth kinetics of ferrite.
1990, 4(2).
Abstract:
Clapeyron equation has been inferred in terms of theories of energy conservation, which is a new method. Based on Clapeyron equation, formulae for calculating critical specific pressure under ideal conditions have been given. Through analysesing hydropressure in composite body, we consider that dydropressure is in linear with specific pressure. Such a view of point has been brought forward that "at the final stage of liquid forging, metals solidify under ideal condition". Furhmore, the concept of coefficient of simultaneous solidification has been put forward. In this paper, formulae for calculating critical specific pressure with different ratio of height to diameter in liquid forging have been given for the first time, they are in good agreement with experimental data.
Clapeyron equation has been inferred in terms of theories of energy conservation, which is a new method. Based on Clapeyron equation, formulae for calculating critical specific pressure under ideal conditions have been given. Through analysesing hydropressure in composite body, we consider that dydropressure is in linear with specific pressure. Such a view of point has been brought forward that "at the final stage of liquid forging, metals solidify under ideal condition". Furhmore, the concept of coefficient of simultaneous solidification has been put forward. In this paper, formulae for calculating critical specific pressure with different ratio of height to diameter in liquid forging have been given for the first time, they are in good agreement with experimental data.
1990, 4(2).
Abstract:
The transient lubrication model for 2-dimensional asperity group with Eyring fluid was extablished in this paper. The lubrication processes of asperity group were analyzed numerically by a finite deference associate with relaxation iteration method. Main interest was focused on the influence of interaction between asperities on lubrication behavior. Results showed that the interaction between asperities has reduced pressure fluctuation and asperity elastic deformation.
The transient lubrication model for 2-dimensional asperity group with Eyring fluid was extablished in this paper. The lubrication processes of asperity group were analyzed numerically by a finite deference associate with relaxation iteration method. Main interest was focused on the influence of interaction between asperities on lubrication behavior. Results showed that the interaction between asperities has reduced pressure fluctuation and asperity elastic deformation.
1990, 4(2).
Abstract:
A modified M-K model was presented in this paper. The theoretical prediction of the stretching forming limit of sheet metals has been realised with the M-K model incorporating with two cases of the Hill (1979) yield criterion. Theoretical calculations show good agreements with the experimental results for several kinds of materials. The choices of yield functions and their parameters are based on either the crystalline plasticity theory or the experimental data.
A modified M-K model was presented in this paper. The theoretical prediction of the stretching forming limit of sheet metals has been realised with the M-K model incorporating with two cases of the Hill (1979) yield criterion. Theoretical calculations show good agreements with the experimental results for several kinds of materials. The choices of yield functions and their parameters are based on either the crystalline plasticity theory or the experimental data.
1990, 4(2).
Abstract:
20, 20Cr, 20Cr2Ni4A, 40Cr and GCr15 steels were internally oxidized for 8 to 80 hours at temperatures between 1133K and 1373K using a powder mixtur of Fe2O3:Fe:Al2O3=1:1:1 in order to determine the diffusion coefficients of oxygen in the steels and in the internal oxidation layer of the steels. Experimental results show that the oxides in the internally oxidized steels are (Mn0.83Fe0.17)(Al1.96Fe0.04)O4, Fe(AlCr)2O4 and Fe2SiO4; the kinetics of internal oxidation of the steels obeys a parabotic rate law. The diffusion coefficient of oxygen in the internal oxidation layer of the steels, D010 was evaluated by means of the kinetics of internal oxidation; Do10 increases with increase of the volume fraction of oxides in internal oxidation layer, f10 The diffusion coefficient of oxygen in the steels (austenite state), D0, was determined by extrapotation of relationship between D010 and f10 to f10=0. Do may be expressed as Do=2.567 exp(-165.32kJ/RT)cm2/s.
20, 20Cr, 20Cr2Ni4A, 40Cr and GCr15 steels were internally oxidized for 8 to 80 hours at temperatures between 1133K and 1373K using a powder mixtur of Fe2O3:Fe:Al2O3=1:1:1 in order to determine the diffusion coefficients of oxygen in the steels and in the internal oxidation layer of the steels. Experimental results show that the oxides in the internally oxidized steels are (Mn0.83Fe0.17)(Al1.96Fe0.04)O4, Fe(AlCr)2O4 and Fe2SiO4; the kinetics of internal oxidation of the steels obeys a parabotic rate law. The diffusion coefficient of oxygen in the internal oxidation layer of the steels, D010 was evaluated by means of the kinetics of internal oxidation; Do10 increases with increase of the volume fraction of oxides in internal oxidation layer, f10 The diffusion coefficient of oxygen in the steels (austenite state), D0, was determined by extrapotation of relationship between D010 and f10 to f10=0. Do may be expressed as Do=2.567 exp(-165.32kJ/RT)cm2/s.
1990, 4(2).
Abstract:
An optimal design forcast steel production, which is based upon computer simulated melt test, can save a large amount of labour, material and time. The model for optimization in the paper is based upon the fact that the computer is able to generate pesuedo random number sequences and to make high speed calculatin. At the same time, the Monte Carlo and complex optimization are also exploited. The results achieved by the model are the design varieties with certain value limits and their corresponding ranges of design indexes. Such results match better to the real production requirements in comparison with those achieved by normal methods,I.e.orthogonal testing and linear programming methods.
An optimal design forcast steel production, which is based upon computer simulated melt test, can save a large amount of labour, material and time. The model for optimization in the paper is based upon the fact that the computer is able to generate pesuedo random number sequences and to make high speed calculatin. At the same time, the Monte Carlo and complex optimization are also exploited. The results achieved by the model are the design varieties with certain value limits and their corresponding ranges of design indexes. Such results match better to the real production requirements in comparison with those achieved by normal methods,I.e.orthogonal testing and linear programming methods.
1990, 4(2).
Abstract:
From the viewpoint of the classical isolation theory of two symmertical planes, the coupling characteristics among subsystems is studied. Then, by applying the matrix perturbation theory, the first and second order terms for the natural frequencies and modal vectors are derived. A practical engineering example is given showing the reference values of the change of natural frequencies.
From the viewpoint of the classical isolation theory of two symmertical planes, the coupling characteristics among subsystems is studied. Then, by applying the matrix perturbation theory, the first and second order terms for the natural frequencies and modal vectors are derived. A practical engineering example is given showing the reference values of the change of natural frequencies.
1990, 4(2).
Abstract:
Self-excited vibrations of rotor systems with tilting-pad bearings caused by negative damping effect of these bearings under certain condition are discussed in detail.
Self-excited vibrations of rotor systems with tilting-pad bearings caused by negative damping effect of these bearings under certain condition are discussed in detail.
1990, 4(2).
Abstract:
This scientific subject which deals with the computer aided design of the cycloid drive includes the following parts: selecting model of the reducer according to the given conditions; selecting tooth profile according to the experts' experience; optimization of parameters and tooth profile; calculation of geometric size and accurate force analysis on major parts; check of strength and analysis on stress-field by finite element method; the computer aided drawing and calculation of measuring size of tooth profile on the cycloidal gear. Using the CAD software, we have designed a complete new series of cycloid speed-reducers.
This scientific subject which deals with the computer aided design of the cycloid drive includes the following parts: selecting model of the reducer according to the given conditions; selecting tooth profile according to the experts' experience; optimization of parameters and tooth profile; calculation of geometric size and accurate force analysis on major parts; check of strength and analysis on stress-field by finite element method; the computer aided drawing and calculation of measuring size of tooth profile on the cycloidal gear. Using the CAD software, we have designed a complete new series of cycloid speed-reducers.
1990, 4(2).
Abstract:
This paper introduces a new system for measuring dynamic accuracy and data processing of gear cutting machine. A new principle of angular displacement transducer and a new synchrotie type device for transmitting radio transformer are sugested. This system has special functions. It is suitable for not only the measurement and analysis of middle-size machine but also that of large-size, large-radio and low speed machine particularly. The software system of data processing is introduced also. A typical example is given.
This paper introduces a new system for measuring dynamic accuracy and data processing of gear cutting machine. A new principle of angular displacement transducer and a new synchrotie type device for transmitting radio transformer are sugested. This system has special functions. It is suitable for not only the measurement and analysis of middle-size machine but also that of large-size, large-radio and low speed machine particularly. The software system of data processing is introduced also. A typical example is given.
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