1998 Vol.11(3)
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1998, 12(3).
Abstract:
The study of nonlinear oscillations and chaos of a railway freight car is undertaken. The vehicle is considered as a multiple rigid-body system with 9 degrees of freedom. The vehicle forward speed is taken as the control parameter of the system. Hopf bifurcation point, limit cycles, quasiperiodic and chaotic motions of the system are computed by use of numerical methods. The identification of periodic, quasiperiodic and chaotic motions of the system is carried out by using the methods of phase plane protrait and Poincare map. Numerical results show that chaotic motion appears via the route of quasiperiodicity when the vehicle runs over a certain speed.
The study of nonlinear oscillations and chaos of a railway freight car is undertaken. The vehicle is considered as a multiple rigid-body system with 9 degrees of freedom. The vehicle forward speed is taken as the control parameter of the system. Hopf bifurcation point, limit cycles, quasiperiodic and chaotic motions of the system are computed by use of numerical methods. The identification of periodic, quasiperiodic and chaotic motions of the system is carried out by using the methods of phase plane protrait and Poincare map. Numerical results show that chaotic motion appears via the route of quasiperiodicity when the vehicle runs over a certain speed.
1998, 12(3).
Abstract:
A numerical method is presented for analysing 2-dimensional quasi-steady state heat transfer in high power density laser kdyhole welding processes. The mathematical model is established according to the conservation of mass, momentum and energy. Computation is performed by using the finite controlvolume method in the curvilinear coordinate system. A position prediction-correction procedure is employed to identify the solid-liquid interface location. This method is applied to the study of a typical keyhole welding process of an AISI 304 stainless steel plate and its feasibility is verified.
A numerical method is presented for analysing 2-dimensional quasi-steady state heat transfer in high power density laser kdyhole welding processes. The mathematical model is established according to the conservation of mass, momentum and energy. Computation is performed by using the finite controlvolume method in the curvilinear coordinate system. A position prediction-correction procedure is employed to identify the solid-liquid interface location. This method is applied to the study of a typical keyhole welding process of an AISI 304 stainless steel plate and its feasibility is verified.
1998, 12(3).
Abstract:
In order to find out the optimal operation comdition for return sands cooler, a cooling model including heat and mass transfer is constructed, and computer simulation is carried out. The results are compared with the operation data obtained from a fluidized bed sand cooler. A method is proposed for the evaluation whether the practical cooling system provides a reasonable energy cost performance. Several key points are discussed concerning enhancement of particles concerning enhancement of particles to air heat removal and improvement of energy effciency for cooling.
In order to find out the optimal operation comdition for return sands cooler, a cooling model including heat and mass transfer is constructed, and computer simulation is carried out. The results are compared with the operation data obtained from a fluidized bed sand cooler. A method is proposed for the evaluation whether the practical cooling system provides a reasonable energy cost performance. Several key points are discussed concerning enhancement of particles concerning enhancement of particles to air heat removal and improvement of energy effciency for cooling.
1998, 12(3).
Abstract:
The theoretical computation model of the composite journal bearing sealed and lubricated with ferrofluid is established. The oil film pressure distribution, temperature field and heat conduction equation of the bearing liner are jointly calculated. The static and dynamic properties of the bearing under condition of different eccentricities and ratios of width to diameter are obtained and discussed. The results show the feasibility of this type of bearing for smaller eccentricities and width to diameter ratios, and that the oil film temperature, which is more subject to be influenced by the rotating speed, is higher than that of the bearing with leakage flow. The key problem of the further development and application of the bearing is to design more reasonable and effective types of seal structures.
The theoretical computation model of the composite journal bearing sealed and lubricated with ferrofluid is established. The oil film pressure distribution, temperature field and heat conduction equation of the bearing liner are jointly calculated. The static and dynamic properties of the bearing under condition of different eccentricities and ratios of width to diameter are obtained and discussed. The results show the feasibility of this type of bearing for smaller eccentricities and width to diameter ratios, and that the oil film temperature, which is more subject to be influenced by the rotating speed, is higher than that of the bearing with leakage flow. The key problem of the further development and application of the bearing is to design more reasonable and effective types of seal structures.
1998, 12(3).
Abstract:
A model of the solution space for all the sensor mechanisms based on the Stewart platform is established, which is a novel and useful tool for investigation of the optimal sensor design. A kind of performance evaluation atlases are plotted within the model of the solution space, which clearly show relationships between the condition numer of Jacobjan matrix and parameters of all the sensor mechanisms. By using the performance atlases, and optimal design for the sensor mechanism can be achieved. Because the elastic joints are proposed for replacing the spherical joints, the Stewart-platform-based sensor can be designed as small as possible.
A model of the solution space for all the sensor mechanisms based on the Stewart platform is established, which is a novel and useful tool for investigation of the optimal sensor design. A kind of performance evaluation atlases are plotted within the model of the solution space, which clearly show relationships between the condition numer of Jacobjan matrix and parameters of all the sensor mechanisms. By using the performance atlases, and optimal design for the sensor mechanism can be achieved. Because the elastic joints are proposed for replacing the spherical joints, the Stewart-platform-based sensor can be designed as small as possible.
1998, 12(3).
Abstract:
The torsional vibration analytical physical model of mine hoist gear-transmission system is set up. The original parameter's calculation method of hoist transmission system are analyzed and discussed. The design sensitivity of natural and dynamic behavior for hoist transmission system are analyzed, including the design sensitivity of natural frequency, the design sensitivity of mode shape and the design sensitivity of dynamic respondence. The torsional vibration dynamic behavior of mine hoist geartransmission system is studied.
The torsional vibration analytical physical model of mine hoist gear-transmission system is set up. The original parameter's calculation method of hoist transmission system are analyzed and discussed. The design sensitivity of natural and dynamic behavior for hoist transmission system are analyzed, including the design sensitivity of natural frequency, the design sensitivity of mode shape and the design sensitivity of dynamic respondence. The torsional vibration dynamic behavior of mine hoist geartransmission system is studied.
1998, 12(3).
Abstract:
Focusing on the components of mechanical rotational body, the data structure and algorithm of component model generation are discussed. Some problems in assembly process of 3-dimensional graph of components are stuied in great detail.
Focusing on the components of mechanical rotational body, the data structure and algorithm of component model generation are discussed. Some problems in assembly process of 3-dimensional graph of components are stuied in great detail.
1998, 12(3).
Abstract:
The formulation of boundary element method for handling contact problems with friction and the technique for high-speed contact analysis are presented. This formulation is based on the idea of modifying the length of contact elements without altering the total number of elements. The high precision of solution and high-speed analysis are verified according to the results of conventional method and analysis method.
The formulation of boundary element method for handling contact problems with friction and the technique for high-speed contact analysis are presented. This formulation is based on the idea of modifying the length of contact elements without altering the total number of elements. The high precision of solution and high-speed analysis are verified according to the results of conventional method and analysis method.
1998, 12(3).
Abstract:
A new concept of design and manufacturing of ruled surface based on line geometry is proposed. Some practical algorithm for CAD system is derived. Some problems in design and manufacturing of ruled surface can be solved by using the algorithm.
A new concept of design and manufacturing of ruled surface based on line geometry is proposed. Some practical algorithm for CAD system is derived. Some problems in design and manufacturing of ruled surface can be solved by using the algorithm.
ESTIMATE ACCURACY OF NONLINEAR COEFFICIENTS OF SQUEEZEFILM DAMPER USING STATE VARIABLE FILTER METHOD
1998, 12(3).
Abstract:
The estimate model for a nonlinear system of squeeze-film damper (SFD) is described. The method of state variable filter (SVF) is used to estimate the coefficients of SFD. The factors which are critical to the estimate accuracy are discussed.
The estimate model for a nonlinear system of squeeze-film damper (SFD) is described. The method of state variable filter (SVF) is used to estimate the coefficients of SFD. The factors which are critical to the estimate accuracy are discussed.
1998, 12(3).
Abstract:
The controllability and observability analysis of thin plate system with parameter uncertainty is presented using the degree of controllability/observability and the robustness index. It provides a guidanece to the design of robust active vibration control for thin plate system.
The controllability and observability analysis of thin plate system with parameter uncertainty is presented using the degree of controllability/observability and the robustness index. It provides a guidanece to the design of robust active vibration control for thin plate system.
1998, 12(3).
Abstract:
SEM shows that flowers-and-like sodium carbonate exists on the surface of sodium silicate sand grains when hardened by carbon dioxide, baculiform sodium acetate exists not only in sand surface but also inside sodium silicate film when hardened by ester method. The strength of sodium silicate sand mainly depends on the point-bridge connecting strength of dewatered sodium silicate film. The performance of reclaimed sodium dilicate sand is determined by the extent of which salinous crystal is eliminated and reasonableness of relevant technological methods.
SEM shows that flowers-and-like sodium carbonate exists on the surface of sodium silicate sand grains when hardened by carbon dioxide, baculiform sodium acetate exists not only in sand surface but also inside sodium silicate film when hardened by ester method. The strength of sodium silicate sand mainly depends on the point-bridge connecting strength of dewatered sodium silicate film. The performance of reclaimed sodium dilicate sand is determined by the extent of which salinous crystal is eliminated and reasonableness of relevant technological methods.
1998, 12(3).
Abstract:
An error processing method is presented based on optimization theory and microcomputer technique which can be successfully used in the cycloidal gear measurement on three dimensional coordinates measuring machine (CMM). In the procedure, the minimum quadratic sum of the normal deviation is used as the object function and the equidistant curve is dealed with instead of the teeth profile. CMM is a high accurate measuring machine which can provide a way to evaluate the accuracy of the cycloidal gear completely.
An error processing method is presented based on optimization theory and microcomputer technique which can be successfully used in the cycloidal gear measurement on three dimensional coordinates measuring machine (CMM). In the procedure, the minimum quadratic sum of the normal deviation is used as the object function and the equidistant curve is dealed with instead of the teeth profile. CMM is a high accurate measuring machine which can provide a way to evaluate the accuracy of the cycloidal gear completely.
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