1998 Vol.11(4)
Display Mode： |
1998, 12(4).
Abstract:
The main factors affecting the dynamic errors of coordinate measuring machines are analyzed. It is pointed out that there are two main contributors to the dynamic errors: One is the rotation of the elements around the joints connected with air bearings and the other is the bending of the elements caused by the dynamic inertial forces. A method for obtaining the displacement errors at the probe position from dynamic rotational errors is presented. The dynamic rotational errors are measured with inductive position sensors and a laser interferometer. The theoretical and experimental results both show that during the process of fast probing, due to the dynamic inertial forces, there are not only large rotation of the elements around the joints connected with air bearings but also large bending of the weak elements themselves.
The main factors affecting the dynamic errors of coordinate measuring machines are analyzed. It is pointed out that there are two main contributors to the dynamic errors: One is the rotation of the elements around the joints connected with air bearings and the other is the bending of the elements caused by the dynamic inertial forces. A method for obtaining the displacement errors at the probe position from dynamic rotational errors is presented. The dynamic rotational errors are measured with inductive position sensors and a laser interferometer. The theoretical and experimental results both show that during the process of fast probing, due to the dynamic inertial forces, there are not only large rotation of the elements around the joints connected with air bearings but also large bending of the weak elements themselves.
1998, 12(4).
Abstract:
The lower extremity forces developed during vehicle acciednts with significant floor pan intrusion are considered, and the forces generated directly by the intrusion are focused on . The analysis is based on the modification and use of SUPERCRASH-a multibody crash computer simulator. For 48 km/h frontal collisions, the results show that there is marked asymmetry on the forces exerted on the left and right legs, arising due to the asymmetrical restraint of the 3-point seat belts. The results also show, as expected, that floor pan intrusion reduction will greatly reduce the forces on the lower extremities.
The lower extremity forces developed during vehicle acciednts with significant floor pan intrusion are considered, and the forces generated directly by the intrusion are focused on . The analysis is based on the modification and use of SUPERCRASH-a multibody crash computer simulator. For 48 km/h frontal collisions, the results show that there is marked asymmetry on the forces exerted on the left and right legs, arising due to the asymmetrical restraint of the 3-point seat belts. The results also show, as expected, that floor pan intrusion reduction will greatly reduce the forces on the lower extremities.
1998, 12(4).
Abstract:
The new flexible forming technique of sheet metal-laser bending process is numerically simulated by using finite element method od large elastic-plastic deformation. The temperature fields and stress-strain distribution in deformation area are calculated, forming process is described and realtionship between bend angle and width of sheet is discussed. It is shown that the calculated values are in good accordance with the experiments.
The new flexible forming technique of sheet metal-laser bending process is numerically simulated by using finite element method od large elastic-plastic deformation. The temperature fields and stress-strain distribution in deformation area are calculated, forming process is described and realtionship between bend angle and width of sheet is discussed. It is shown that the calculated values are in good accordance with the experiments.
1998, 12(4).
Abstract:
An optimal design problem of local buffer allocation in the FMS is discussed in order to maximize a reward earned from processed jobs at all workstations. Structural properties of the optimal design problem are analyzed for the model with two job routing policies. Based on these properties, approaches to optimal solutions are given.
An optimal design problem of local buffer allocation in the FMS is discussed in order to maximize a reward earned from processed jobs at all workstations. Structural properties of the optimal design problem are analyzed for the model with two job routing policies. Based on these properties, approaches to optimal solutions are given.
1998, 12(4).
Abstract:
The three-ring reducer is studied both in theory and experiment. In order to improve the dynamic characteristics and reduce the vibration and noise, based on the sensitivity analysis of design parameters of dynamic characteristics, the system geometry parameters are optimized, and the structure of reducer is developed according to the optimum result, then the specimens of reducer are disigned and manufactured. The effect of the structure development has been verified by comparing the original and developed according to the optimum result, then the speciments of reducer are designed and manufactured. The effect of the structure development has been verified by comparing the original and developed reducer are designed and developed reducer through the vibration tests.
The three-ring reducer is studied both in theory and experiment. In order to improve the dynamic characteristics and reduce the vibration and noise, based on the sensitivity analysis of design parameters of dynamic characteristics, the system geometry parameters are optimized, and the structure of reducer is developed according to the optimum result, then the specimens of reducer are disigned and manufactured. The effect of the structure development has been verified by comparing the original and developed according to the optimum result, then the speciments of reducer are designed and manufactured. The effect of the structure development has been verified by comparing the original and developed reducer are designed and developed reducer through the vibration tests.
1998, 12(4).
Abstract:
A new type of 4-high strip mill is developed, in which gauge and shape are combinatively controlled by work roll deviating and crossing. The neewly developed 300 mm 4-h mill and its control system are introduced. Both static and dynamic experiments as well as theoretical study are carried out to verify the advantages and the combined shape and gauge control function of this new mill.
A new type of 4-high strip mill is developed, in which gauge and shape are combinatively controlled by work roll deviating and crossing. The neewly developed 300 mm 4-h mill and its control system are introduced. Both static and dynamic experiments as well as theoretical study are carried out to verify the advantages and the combined shape and gauge control function of this new mill.
1998, 12(4).
Abstract:
The contact model of lapping and polishing for magnetic disk substrate is presented. Based on elastic contact theory. Pressure distribution for this model are analyzed. Further, the effects of various parameters ,such as the material properties of the PVA (polyvinyl acetate), grinding stone, te polishing pad and the base plate, the thickness of the pad or the stone on the pressure distribution have been discussed.
The contact model of lapping and polishing for magnetic disk substrate is presented. Based on elastic contact theory. Pressure distribution for this model are analyzed. Further, the effects of various parameters ,such as the material properties of the PVA (polyvinyl acetate), grinding stone, te polishing pad and the base plate, the thickness of the pad or the stone on the pressure distribution have been discussed.
1998, 12(4).
Abstract:
Based on the fuzzy set theory and the expand principle, using fuzzy number as the boundary condition of fault tree analysis, a new method of analyzing fuzzy fault probability of the top event is develpoed. Fuzzy importance analysis of the basic event is proposed as well. A practical example is given. This method is a new way to solve the obscure problems of fault tree analysis and has great value in engineering practice.
Based on the fuzzy set theory and the expand principle, using fuzzy number as the boundary condition of fault tree analysis, a new method of analyzing fuzzy fault probability of the top event is develpoed. Fuzzy importance analysis of the basic event is proposed as well. A practical example is given. This method is a new way to solve the obscure problems of fault tree analysis and has great value in engineering practice.
1998, 12(4).
Abstract:
Sampling principle and characteristics and edge effect of orthogonal wavelet transform of signals are researched. Two samples of signals and wavelet bases must be taken in wavelet transform. In the second sample sampling interval or sampling length in different frequency range will be automatically adjusted. Wavelet transform can detect singular points. Both ends of signals are singular points. Edge effect is not avoidable.
Sampling principle and characteristics and edge effect of orthogonal wavelet transform of signals are researched. Two samples of signals and wavelet bases must be taken in wavelet transform. In the second sample sampling interval or sampling length in different frequency range will be automatically adjusted. Wavelet transform can detect singular points. Both ends of signals are singular points. Edge effect is not avoidable.
1998, 12(4).
Abstract:
One of the design methods for closing the end of a pressure cylinder is to screw down a screw plug on he threaded end of the cylinder. In this case, there is the problem of stress concentration in the threaded end of the pressure cylinder. To solve the problem, it is necessary to know accurately the load distribution on the threaded end of the cylinder. To find the load distribution on the threaded end of the pressure cylinder engaged with the screw plug the following experiments are carried out. Applying the tensile load betwwen the screw plug and the pressure cylinder and regarding the situation above as equivalent to the situation in which the internal pressure is applied, the load distribution is measured with the strain gauge. The influence of thread pitch on the load distribution on te threaded end of the cylinder is presented and an optimum pitch for design is discussed.
One of the design methods for closing the end of a pressure cylinder is to screw down a screw plug on he threaded end of the cylinder. In this case, there is the problem of stress concentration in the threaded end of the pressure cylinder. To solve the problem, it is necessary to know accurately the load distribution on the threaded end of the cylinder. To find the load distribution on the threaded end of the pressure cylinder engaged with the screw plug the following experiments are carried out. Applying the tensile load betwwen the screw plug and the pressure cylinder and regarding the situation above as equivalent to the situation in which the internal pressure is applied, the load distribution is measured with the strain gauge. The influence of thread pitch on the load distribution on te threaded end of the cylinder is presented and an optimum pitch for design is discussed.
1998, 12(4).
Abstract:
A new learing control law is presented which can obtain learning gain matrices from a recursive idenfifier along the learning axis. The system convergence is proved when disturbances exist in the system. Finally it is applied to pneumatic servo control system, the experiment results show its validity.
A new learing control law is presented which can obtain learning gain matrices from a recursive idenfifier along the learning axis. The system convergence is proved when disturbances exist in the system. Finally it is applied to pneumatic servo control system, the experiment results show its validity.
1998, 12(4).
Abstract:
A theoretical model is developed to predict the sound radiation ablity of a cylindrical thin elastic shell of finite length, covered with a damp layer and terminated with infinite cylindrical rigid baffles. This shell is immersed in a heavy fluid extending up to infinity, and excited by a constant point load continuously traveling along the circumferential direction. A frequency-domain representation of the rotating load and three equations of the vibroacoustic coupling problem are given. The equations are solved by means of modal analysis method and asymptotic expansion method. Also, a mathematical expression of modal amplitude of shell radial displacement is obtained. The sound radiation ability of this kind of shell is evaluted and the correponding numerical results are given.
A theoretical model is developed to predict the sound radiation ablity of a cylindrical thin elastic shell of finite length, covered with a damp layer and terminated with infinite cylindrical rigid baffles. This shell is immersed in a heavy fluid extending up to infinity, and excited by a constant point load continuously traveling along the circumferential direction. A frequency-domain representation of the rotating load and three equations of the vibroacoustic coupling problem are given. The equations are solved by means of modal analysis method and asymptotic expansion method. Also, a mathematical expression of modal amplitude of shell radial displacement is obtained. The sound radiation ability of this kind of shell is evaluted and the correponding numerical results are given.
1998, 12(4).
Abstract:
The fatigue crack initiation from notch root and the short-crack growth laws of two medium carbon alloying structural steels-35CrMo and 42CrMo are investigated under the different stress ratios R=0.1,0.3 and three-point bending condition. The relationships between the maximum stress range at the notch root Δσmax and the number of cycles before fatigue crack initiation Ni and determined. The threshold stresses of fatigue crack initiation (Δσmax)th are got, and the smallcrack growth laws are obtained for these steels. An effective and convenient method is proposed for predicting the fatigue life of the notch specimens.
The fatigue crack initiation from notch root and the short-crack growth laws of two medium carbon alloying structural steels-35CrMo and 42CrMo are investigated under the different stress ratios R=0.1,0.3 and three-point bending condition. The relationships between the maximum stress range at the notch root Δσmax and the number of cycles before fatigue crack initiation Ni and determined. The threshold stresses of fatigue crack initiation (Δσmax)th are got, and the smallcrack growth laws are obtained for these steels. An effective and convenient method is proposed for predicting the fatigue life of the notch specimens.
E-mail Alerts
