1992 Vol.5(4)
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1992, 6(4).
Abstract:
This paper presents the quantitative relationship between ductile-brittle transition temperature, TC, and the size of cleavage fracture unit, dr, in steels 10, 20, 35, 45, 55, 70, T8A and 38CrA. The following equation is obtained. It was descovered that the cleavage fracture unit is a material's constant, it has no relation to the shape or notch of specimen, form of notch, and experimental conditions. The process of ductile-brittle transition is a process of variation of the quantity of cleavage fracture units. Therefore, the size of cleavage fracture unit may be considered as a characteristic parameter of microfracture during ductile-brittle transition of materials and as a basis for diagnosis of cold short fracture.
This paper presents the quantitative relationship between ductile-brittle transition temperature, TC, and the size of cleavage fracture unit, dr, in steels 10, 20, 35, 45, 55, 70, T8A and 38CrA. The following equation is obtained. It was descovered that the cleavage fracture unit is a material's constant, it has no relation to the shape or notch of specimen, form of notch, and experimental conditions. The process of ductile-brittle transition is a process of variation of the quantity of cleavage fracture units. Therefore, the size of cleavage fracture unit may be considered as a characteristic parameter of microfracture during ductile-brittle transition of materials and as a basis for diagnosis of cold short fracture.
1992, 6(4).
Abstract:
In this paper, two new theories are proposed for upsetting a cylinder between common flat platens according to the ratio of height to diameter H/D of upsetting body, that is, tension stress theory of a rigid plastic mechanical model for H/D > 1 and shear stress theory of a hydrostatic stress mechanical model for H/D ﹤1. The new theories may properly describe the approximate distribution law of the internal stresses, which have been testified by experiments. The theories correct the wrong viewpoint and incomplete statement on upsetting in plastic mechanics. They are of value to theory and engineering use.
In this paper, two new theories are proposed for upsetting a cylinder between common flat platens according to the ratio of height to diameter H/D of upsetting body, that is, tension stress theory of a rigid plastic mechanical model for H/D > 1 and shear stress theory of a hydrostatic stress mechanical model for H/D ﹤1. The new theories may properly describe the approximate distribution law of the internal stresses, which have been testified by experiments. The theories correct the wrong viewpoint and incomplete statement on upsetting in plastic mechanics. They are of value to theory and engineering use.
1992, 6(4).
Abstract:
Generally, the brake horsepower of a centrifugal pump increases with flow, which causes tremendous destruction of motors by overload with pump operating at greater flow and lower head than normal. The paper derives the theoretical condition of obtaining the saturation brake horsepower characteristics. Methods to draw dimensionless brake horsepower curves are introduced. Restrained equations, design coefficients and an example of non-overload centrifugal pumps are given.
Generally, the brake horsepower of a centrifugal pump increases with flow, which causes tremendous destruction of motors by overload with pump operating at greater flow and lower head than normal. The paper derives the theoretical condition of obtaining the saturation brake horsepower characteristics. Methods to draw dimensionless brake horsepower curves are introduced. Restrained equations, design coefficients and an example of non-overload centrifugal pumps are given.
1992, 6(4).
Abstract:
In this paper, the comprehensive relationships among TNDT, A and D/-1/2 are investigated for smooth tensile specimens of steel 38CrA. The following equations are obtained. According to the equations mentioned above, a three dimensional cold short fracture controlling and mechanism diagram is establised. It can be used not only in the analysis, diagnosis, calculation, controlling and prevention of cold short fracture, but also in the design, choice of materials and safe evaluation of parts at low temperature.
In this paper, the comprehensive relationships among TNDT, A and D/-1/2 are investigated for smooth tensile specimens of steel 38CrA. The following equations are obtained. According to the equations mentioned above, a three dimensional cold short fracture controlling and mechanism diagram is establised. It can be used not only in the analysis, diagnosis, calculation, controlling and prevention of cold short fracture, but also in the design, choice of materials and safe evaluation of parts at low temperature.
1992, 6(4).
Abstract:
In this paper the following quantitative and semi-quantitative relationships were derived experimentally and theoretically. These relationships are significant in revealing the nature of ductile-brittle transition and establishing their quantitative relationships and engineering applications.
In this paper the following quantitative and semi-quantitative relationships were derived experimentally and theoretically. These relationships are significant in revealing the nature of ductile-brittle transition and establishing their quantitative relationships and engineering applications.
1992, 6(4).
Abstract:
In this paper, skewness and kurtosis coafficients are first used in research on the lostmotion distribution of gear train. The formulas for quantitative analysis of lostmotion distribution are given. At the same time, several kinds of gear train are tested and verified by experiment and Monte-Carlo simulation test.
In this paper, skewness and kurtosis coafficients are first used in research on the lostmotion distribution of gear train. The formulas for quantitative analysis of lostmotion distribution are given. At the same time, several kinds of gear train are tested and verified by experiment and Monte-Carlo simulation test.
1992, 6(4).
Abstract:
The area-machining of complex surfaces is explored in this paper, and the cutter location-calculation and control methods in parameter-zone are discussed. The tool path is designed according to different types of area-machining. An unified algorithm of generating tool path is described, that can solve the problem of area-machining for complex surfaces effectively.
The area-machining of complex surfaces is explored in this paper, and the cutter location-calculation and control methods in parameter-zone are discussed. The tool path is designed according to different types of area-machining. An unified algorithm of generating tool path is described, that can solve the problem of area-machining for complex surfaces effectively.
1992, 6(4).
Abstract:
After briefly describing H.Czichos's solving method of tribological problem of unit tribology system based on experiments this paper presents a solving method of intellingent CAD system based on computer, and presents the solving line by the computer for the piston ring and cylinder liner system. It is possible that the tribological problem of machine parts may be considered overally and systematically in design step.
After briefly describing H.Czichos's solving method of tribological problem of unit tribology system based on experiments this paper presents a solving method of intellingent CAD system based on computer, and presents the solving line by the computer for the piston ring and cylinder liner system. It is possible that the tribological problem of machine parts may be considered overally and systematically in design step.
1992, 6(4).
Abstract:
In present study pattern recognition of weld joint is studied for welding process controd, with linear CCD as sensor. A N-dimensional state vector is proposed by the authors to describe the image figure and a 4-dimensional characteristic feature vector is extracted from it for recognition of the cross section contour of the welding joint. Instructions are then generated according to the characteristic feature vector of real-time control of the torch position and parameters of the welding process.
In present study pattern recognition of weld joint is studied for welding process controd, with linear CCD as sensor. A N-dimensional state vector is proposed by the authors to describe the image figure and a 4-dimensional characteristic feature vector is extracted from it for recognition of the cross section contour of the welding joint. Instructions are then generated according to the characteristic feature vector of real-time control of the torch position and parameters of the welding process.
1992, 6(4).
Abstract:
The microstrural changes in worn surfaces of 6Mn-2Cr and Mn13 steels before and after wear were investigated by the use of back scattering Mossbauer spectroscopy. The results show that there exist two kinds of austenite for the austenitic manganese steels before wear, one almost contains no C and the other contains C. The carbon atoms mainly exist in the octahedren gap positions of austenite. There is only one carbon atom as nearest neighbour around an iron atom. Correspondingly two kinds of strain-induced martensite are produced in the worn surface of 6Mn-2Cr steel while wearing,. One is C and Me-free martensite whose internal magnetic field value equals to 33.0 T and the other is C and Me-containing martensite whose internal magnetic field value equals to 30.5T. The C and Me-free martensite is produced under a lower wear impact energy firstly and its weight fraction reaches the saturated value rapidly. However, the C and Me-containing martensite ois produced under a higher wear impact energy and its weight fraction increases with increasing of the impact energy of wear tests. There exist no stranin-induced martensite transformation in Mn13 steel while wearing.
The microstrural changes in worn surfaces of 6Mn-2Cr and Mn13 steels before and after wear were investigated by the use of back scattering Mossbauer spectroscopy. The results show that there exist two kinds of austenite for the austenitic manganese steels before wear, one almost contains no C and the other contains C. The carbon atoms mainly exist in the octahedren gap positions of austenite. There is only one carbon atom as nearest neighbour around an iron atom. Correspondingly two kinds of strain-induced martensite are produced in the worn surface of 6Mn-2Cr steel while wearing,. One is C and Me-free martensite whose internal magnetic field value equals to 33.0 T and the other is C and Me-containing martensite whose internal magnetic field value equals to 30.5T. The C and Me-free martensite is produced under a lower wear impact energy firstly and its weight fraction reaches the saturated value rapidly. However, the C and Me-containing martensite ois produced under a higher wear impact energy and its weight fraction increases with increasing of the impact energy of wear tests. There exist no stranin-induced martensite transformation in Mn13 steel while wearing.
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