1988 Vol.1(2)
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1988, 2(2).
Abstract:
In this paper the temperature distribution on the tool in milling of difficult-to-out materials has been experimentally investigated by means of the method of metallographic structure changes of the high speed steel tool. The three-dimensional non-steady state temperature fields in milling has also been calculated with the finite difference method. The experimental and calculated results are in fairly good agreement. It has been revealed that on the tool flank exists a high temperature region with the shape similar to that of the crater on the tool rake face. It is the main cause of flank wear in milling difficult-to-cut materials.
In this paper the temperature distribution on the tool in milling of difficult-to-out materials has been experimentally investigated by means of the method of metallographic structure changes of the high speed steel tool. The three-dimensional non-steady state temperature fields in milling has also been calculated with the finite difference method. The experimental and calculated results are in fairly good agreement. It has been revealed that on the tool flank exists a high temperature region with the shape similar to that of the crater on the tool rake face. It is the main cause of flank wear in milling difficult-to-cut materials.
1988, 2(2).
Abstract:
In this experimental investigation, grinding tests under 40-80m/s wheel speeds and 1000-6000N loads were made on a specially made snag grinding machine and a slab grinder. This paper deals with the relationship among working parameters and various factors. The mechanism of heavy grinding is discussed based upon test results and observations on cutting chips, grains on wheel surface, etc. The investigation shows that hign speed heavy grinding (HSHG) has much more economic benefit than ordinary snag grinding used in domestic steel mills and is an effective approach to the development of snagging technology in our country. It also depicts the characteristics and laws of high speed heavy grinding.
In this experimental investigation, grinding tests under 40-80m/s wheel speeds and 1000-6000N loads were made on a specially made snag grinding machine and a slab grinder. This paper deals with the relationship among working parameters and various factors. The mechanism of heavy grinding is discussed based upon test results and observations on cutting chips, grains on wheel surface, etc. The investigation shows that hign speed heavy grinding (HSHG) has much more economic benefit than ordinary snag grinding used in domestic steel mills and is an effective approach to the development of snagging technology in our country. It also depicts the characteristics and laws of high speed heavy grinding.
1988, 2(2).
Abstract:
The path-independence property of the J-integral for a non-homogeneous panel with a sandwiched hard layer containing a centre crack parallel to the interfaces, and the validity of J are investigated by means of elastoplastic FEM by applying the J-integral method to the safety assessment of welded joints with mechanical non-homogeneity. It is shown that the J-integral remains path-independent and J as the rate of decrease of potential energy is still applicable in spite of non-homogeneity. The path-independence of J in such a non-homogeneous environment is also confirmed mathematically. The effect of mechanical non-homogeneity upon the J-integral values is studied. It is concluded that the yielding of the two soft zones between which the hard layer is sandwiched tends to make the J values increase: the smaller the relative hard layer width h/2a, the larger are the J values at the same load level.
The path-independence property of the J-integral for a non-homogeneous panel with a sandwiched hard layer containing a centre crack parallel to the interfaces, and the validity of J are investigated by means of elastoplastic FEM by applying the J-integral method to the safety assessment of welded joints with mechanical non-homogeneity. It is shown that the J-integral remains path-independent and J as the rate of decrease of potential energy is still applicable in spite of non-homogeneity. The path-independence of J in such a non-homogeneous environment is also confirmed mathematically. The effect of mechanical non-homogeneity upon the J-integral values is studied. It is concluded that the yielding of the two soft zones between which the hard layer is sandwiched tends to make the J values increase: the smaller the relative hard layer width h/2a, the larger are the J values at the same load level.
1988, 2(2).
Abstract:
This paper points out the shortcomins for practical application of C.J. hooke's LS (lubrication status) diagram and introduces a LS diagram involving Grubin's theory that can be used in the engineering calculations. The minumum oil film thickess has been analyzed from the boundary of two lubrication theories. Both the theoretical foundation and the concrete method has been provided and discussed.
This paper points out the shortcomins for practical application of C.J. hooke's LS (lubrication status) diagram and introduces a LS diagram involving Grubin's theory that can be used in the engineering calculations. The minumum oil film thickess has been analyzed from the boundary of two lubrication theories. Both the theoretical foundation and the concrete method has been provided and discussed.
1988, 2(2).
Abstract:
The initiation and propagation of fatigue cracks from notches have been studied in a high strength aluminium alloy 7010-T736. The experimental results suggest that a modified effective stress intensity factor, which is described by introducing function of microstructure scale, notch geometry and short crack length, is applicable to predict initiation of fatigue crack emanating from notches and fatigue crack propagetion within the notch stress field.
The initiation and propagation of fatigue cracks from notches have been studied in a high strength aluminium alloy 7010-T736. The experimental results suggest that a modified effective stress intensity factor, which is described by introducing function of microstructure scale, notch geometry and short crack length, is applicable to predict initiation of fatigue crack emanating from notches and fatigue crack propagetion within the notch stress field.
1988, 2(2).
Abstract:
In this paper the questions about pinion type cutter for straignt-sided internal spline on the selection of maximum allowable teeth number without plunge or withdraw top cut, on the determination of the maximum allowable withdraw value after resharpening etc. are studied and an appropriate conclusion and some practicable formulars are advanced.
In this paper the questions about pinion type cutter for straignt-sided internal spline on the selection of maximum allowable teeth number without plunge or withdraw top cut, on the determination of the maximum allowable withdraw value after resharpening etc. are studied and an appropriate conclusion and some practicable formulars are advanced.
1988, 2(2).
Abstract:
In this paper, an attempt has been made to improve the design calculation method for radial impellers with consideration of the viscous property of real gas. The viscous fluid flow equations in turbomachines are given in its full tensor form and hereof, in its velocity gradient form along arbitrary curved directon. The method of solution is outlined for pure radial impeller. Features of the simplified method and the traeatment of boundary conditions are emphasized in description. The encouraging calculation rasult and analysis of a typical example are given in brief.
In this paper, an attempt has been made to improve the design calculation method for radial impellers with consideration of the viscous property of real gas. The viscous fluid flow equations in turbomachines are given in its full tensor form and hereof, in its velocity gradient form along arbitrary curved directon. The method of solution is outlined for pure radial impeller. Features of the simplified method and the traeatment of boundary conditions are emphasized in description. The encouraging calculation rasult and analysis of a typical example are given in brief.
1988, 2(2).
Abstract:
Any plane multi-link non-dyad complex mechanism can be transformed into dyad mechanism with increasing number of degrees-of-freedom by the method of imaginarily disconnecting certain links and paris. According to the geometric identity conditions established for the transformed dyad mechanism. The position analysis of the original mechanism can be carried out with high accuracy via successive linear interpolation. According to the velocity and acceleration identity conditions, the velocity and acceleration analysis of the original mechanism can be readily accomplished via the principle of linear superposition. This method of kinematic analysis is quite easy and general. In the paper two examples are given to show the effectiveness of method.
Any plane multi-link non-dyad complex mechanism can be transformed into dyad mechanism with increasing number of degrees-of-freedom by the method of imaginarily disconnecting certain links and paris. According to the geometric identity conditions established for the transformed dyad mechanism. The position analysis of the original mechanism can be carried out with high accuracy via successive linear interpolation. According to the velocity and acceleration identity conditions, the velocity and acceleration analysis of the original mechanism can be readily accomplished via the principle of linear superposition. This method of kinematic analysis is quite easy and general. In the paper two examples are given to show the effectiveness of method.
1988, 2(2).
Abstract:
In this paper, theoretical calculation and experimental measurement about thermal effect on static characteristics of elliptical bearings are carried out. The heat transfer bewteen film and both of shaft and bush, the effect of elastic deformation of bush are taken into account. In addition, the temperature distribution of bush, eccentricity ratios and flow rates have been measured under different conditions of rotational speeds and loads. The theoretical results rather agree with the experimental data.
In this paper, theoretical calculation and experimental measurement about thermal effect on static characteristics of elliptical bearings are carried out. The heat transfer bewteen film and both of shaft and bush, the effect of elastic deformation of bush are taken into account. In addition, the temperature distribution of bush, eccentricity ratios and flow rates have been measured under different conditions of rotational speeds and loads. The theoretical results rather agree with the experimental data.
1988, 2(2).
Abstract:
Theoretical analyses and experiments on acceleration measuring systems currently used in this country for rolling bearings were carried out and the following conclusions are arrived at:1. A consistent value of resonance frequency between (3-4) kHz of the springloaded piezo-electric acceleration measuring system adopted in practice was obtained from the results of theoretical calculation, testing of sensoring system and frequency spectrum of rollong bearing vibration tests. 2. It was proved by thoretical analyses and experiments that the application of oil between the probe and the bearing outer ring in a bearing vibration testing system using piezo-electric accelerometer could reduce the resonance amplituede of the system, but could not raise the resonance frequency above 10 kHz. The resonance frequency still remained between (3-4) kHz. 3. A resonance frequency around 12 kHz of the moving-coil type veloctity sensoring system for rolling bearing vibration test was obtained. It is that the vibration frequency of rolling bearing varies between 50 Hz to 10 kHz. A resonance frequency of the moving-coil type velocity sensor around 12 kHz enabels the later to show the true behavior of bearing vibration, whereas a resonance frequency between(3-4)kHz of the probe type piezo-electric accelerometer sensoring system will affect of trueness the measured natural frequency, making it uncapable of reflecting the true behavior of bearing vibration. Therefore, the velocity sensoring system is more suitable than the acceleration sensoring system, and the moving-coil type sensor, measuring the velocity, is recommended for rolling bearing vibration test.
Theoretical analyses and experiments on acceleration measuring systems currently used in this country for rolling bearings were carried out and the following conclusions are arrived at:1. A consistent value of resonance frequency between (3-4) kHz of the springloaded piezo-electric acceleration measuring system adopted in practice was obtained from the results of theoretical calculation, testing of sensoring system and frequency spectrum of rollong bearing vibration tests. 2. It was proved by thoretical analyses and experiments that the application of oil between the probe and the bearing outer ring in a bearing vibration testing system using piezo-electric accelerometer could reduce the resonance amplituede of the system, but could not raise the resonance frequency above 10 kHz. The resonance frequency still remained between (3-4) kHz. 3. A resonance frequency around 12 kHz of the moving-coil type veloctity sensoring system for rolling bearing vibration test was obtained. It is that the vibration frequency of rolling bearing varies between 50 Hz to 10 kHz. A resonance frequency of the moving-coil type velocity sensor around 12 kHz enabels the later to show the true behavior of bearing vibration, whereas a resonance frequency between(3-4)kHz of the probe type piezo-electric accelerometer sensoring system will affect of trueness the measured natural frequency, making it uncapable of reflecting the true behavior of bearing vibration. Therefore, the velocity sensoring system is more suitable than the acceleration sensoring system, and the moving-coil type sensor, measuring the velocity, is recommended for rolling bearing vibration test.
1988, 2(2).
Abstract:
With the development of high performance and high pressure ratio centrifugal compressor, reference[1] pointed out that the elliptic type is an optimal vane shape during higher pressure ratio. This paper presents a profiling method of elliptic vane shape, in which a simple polar equation with elliptic center as pole is established by adopting the polar coordinates instead of Descartes coordinates. The relationship between vane camber angle βs,βh [2][3] and polar angle ψ is directly derived to give the distribution of vane camber angles βs,βh along the revolution surface of hub and shroud. As an example, the author calculated a centrifugal impeller with a diameter of 95mm just to show that this method is simple and feasible.
With the development of high performance and high pressure ratio centrifugal compressor, reference[1] pointed out that the elliptic type is an optimal vane shape during higher pressure ratio. This paper presents a profiling method of elliptic vane shape, in which a simple polar equation with elliptic center as pole is established by adopting the polar coordinates instead of Descartes coordinates. The relationship between vane camber angle βs,βh [2][3] and polar angle ψ is directly derived to give the distribution of vane camber angles βs,βh along the revolution surface of hub and shroud. As an example, the author calculated a centrifugal impeller with a diameter of 95mm just to show that this method is simple and feasible.
1988, 2(2).
Abstract:
By combining an optical phase comparison method with a Zeeman-laser, a high resolution heterodyne interference measurement system has been developed. It can be used for direct measurement of the refractive index of air. The uncertainty of dn/n was confirmed by a great number of experiments to be no more than 5×10-8.
By combining an optical phase comparison method with a Zeeman-laser, a high resolution heterodyne interference measurement system has been developed. It can be used for direct measurement of the refractive index of air. The uncertainty of dn/n was confirmed by a great number of experiments to be no more than 5×10-8.
1988, 2(2).
Abstract:
The present paper is concerned with shakedown problem of thick-walled cylindrical tube under internal pressure during loading, unloading and reloading. By using elastic-power hardening model the shakedown load of such thick-walled cylindrical tube is obtained for isotropic and kinematical hardening assumptions.
The present paper is concerned with shakedown problem of thick-walled cylindrical tube under internal pressure during loading, unloading and reloading. By using elastic-power hardening model the shakedown load of such thick-walled cylindrical tube is obtained for isotropic and kinematical hardening assumptions.
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