Torsional Vibration System Research Articles

Phenomenon of carved driving wheels

A newly found phenomenon of carved driving wheels of a rear-wheel-drive tractor used in an airport is discussed. The circum of every driving wheel is damaged at three regions,which distribute regularly and uniformly. Everyday,the tractor tows a trailer which are times heavier than the tractor,and moves on the same road in the airport. The phenomenon is explained by the torsional self-excited vibration system of the powertrain. The simplified torsional vibration system is discribed by a 2-order ordinary differential equation,which has a limit circle. Experiments and numerical simulations show the followings: Because of the heavy trailer,the slip ratio of the tractor’s driving wheels is very large. Therefore,there is severe torsional self-excited vibration in the tractor’s drivetrain,and the self-excited vibration results in severe and regular fluctuations of the rear wheel’s velocity. The severe fluctuations in velocity fastens the damage of the driving wheels. At the same time,the time interval in which an arbitrary point in the circum of the driving wheel contacts with the road twice is two times more than the period of the torsional self-excited vibration,and this times explained the existence of three damaged regions. At last,it points out that the phenomenon can be avoided when the torsional damping is large enough.

TORSIONAL VIBRATION CALCULATION OF ROLLING MILL BASED ON TOPOLOGY NETWORK

For solving the problem of dynamic characteristic of rolling mill main drive system's torsinal vibration on complex-branch system, a kind of topology network structure model of torsional vibration is studied by using system dynamic theory. The new model include internal and external damping properties. In this work , some different typical types of torsional response are calculated and analyzed, which acquired well consistency between the new methods and the classical methods through the calculation example and simulation. It supplies a kind of new ways to calculate and analysis the complex multi-branch drive torsional vibration system in engineer and practice and for solving the similar problems. Also the topology network representation can easy be input for the control system and exploit a new means on real-time control or fault diagnosis monitor for the heavy-duty machinery's main drive torsional vibration system.

Torsional Vibration Suppression by Using Wave Absorbing Filter

The effect of the wave absorbing filter for torsional vibration system consisted of solid discs and torsional bars has been investigated both theoretically and experimentally. Two wave absorbing filters are developed based on the impedance matching condition, one is by introducing a 1-degrees-of-freedom imaginary system which has the impedance matching condition at an end (imaginary type), and the other is by changing the boundary condition to apply the impedance matching condition directly at the boundary (boundary type). The irrational transfer function of the impedance matching condition is numerically approximated as 6-order polynomials by using a curve-fitting technique. As the result of experiment both filters have shown to work very well compared to the authors' former wave control strategy(4) using a large degrees-of-freedom imaginary system and its initialization. The experiments of 2-and 3-degrees-of-freedom controlled system show the wave propagating state as the phase shift between adjoining elements, which correspond to the theoretical result. By comparing the effects of both filters, the boundary type is better than the imaginary type in the case without small sampling period, 4 ms in our experimental apparatus.

Interval optimization for uncertain structures

This paper presents an interval optimization method to solve the uncertain problems of the vibration systems with multi-degrees of freedom, where the structural characteristics are assumed to be expressed as interval parameters. Combining the interval extension of function with the first-order Taylor expansions of the functions, the interval optimization method is derived. The present method is implemented for a torsional vibration system and a frame structure. The numerical results show that the method is effective, and that the present method can provide more information about the optimization results than those obtained by the deterministic optimization.

Interval optimization for uncertain structures

This paper presents an interval optimization method to solve the uncertain problems of the vibration systems with multi-degrees of freedom, where the structural characteristics are assumed to be expressed as interval parameters. Combining the interval extension of function with the first-order Taylor expansions of the functions, the interval optimization method is derived. The present method is implemented for a torsional vibration system and a frame structure. The numerical results show that the method is effective, and that the present method can provide more information about the optimization results than those obtained by the deterministic optimization.

205 仮想系によるねじり振動系の波動吸収制御(波動の制御,OS-1 先端的・萌芽的制御技術とその応用)

205 仮想系によるねじり振動系の波動吸収制御(波動の制御,OS-1 先端的・萌芽的制御技術とその応用)

Optimum control to a partially controlled turbogenerator shaft torsional vibration system

The optimal control to a partially controlled turbogenerator shaft torsional vibration system is investigated. The principle of input feedforward control is presented to achieve the minimum of the average vibration energy in a system,and the optimal control matrix of the system is derived. A turbogenerator shaft system is taken as an example to simulate the optimal control process of the torsional vibration. Results from this simulation indicate that the vibration can be effectively controlled by a partial control strategy.

Transverse and torsional complex vibration systems for ultrasonic seam welding of metal plates

Transverse and torsional complex vibration systems for ultrasonic seam welding of metal plate specimens, using a 27 kHz complex vibration disk welding tip vibrating in transverse and torsional vibration modes, were studied. Using a complex vibration welding system with a welding tip vibrating in elliptical or circular locus, thick plate specimens can be welded with a more uniform and larger area compared to a conventional ultrasonic welding system. The disk welding tip vibrates in an elliptical or circular locus. The complex vibration system can continuously weld multiple parts of metal plate specimens such as heat sinks with a large number of fins.

On-line sensing techniques for coagulum setting in renneted milks

In cheesemaking, the on-line measurement of clotting time, coagulum firmness and cutting point is useful for process monitoring but has proven difficult to carry out. This work presents a comparison of on-line sensors, more or less capable of allowing the determination of these data. An experiment was undertaken in which six on-line sensors, comprising of optical systems (NIR transmission X2 wavelengths and NIR reflectance), hot-wire, and vibrational systems (torsional and transverse), were used simultaneously to monitor milk coagulation in trials where protein levels and enzyme concentrations were varied and the sensor response characteristics were compared with oscillatory shear measurements. It was found that protein level mainly influenced curd firming rate, while rennet level mainly influenced gel time. Up to three coagulation parameters were derived using each sensor. While all sensors were able to detect the effect of rennet level, which is mainly seen in the gelation (or clotting) time, the sensors varied in their sensitivity to changes in protein level, which mainly affects the curd-firming time. For some sensors, a combination of response parameters was shown by multiple linear regression to be advantageous for predicting coagulum-firming time. By combining response parameters in this way the standard errors of prediction of coagulum cutting point (using oscillatory shear measurements as the reference) were better than 100 s for NIR reflectance, NIR transmission and low-frequency vibration systems as compared with ca.300 s for the hot-wire or torsional vibration systems.

Analysis of Torsional Vibration Systems by the Extended Transfer Matrix Method

This study applies the extended transfer matrix method and Newton-Raphson technique with complex numbers for torsional vibration analysis of damped systems. The relationships of the vibratory amplitude, the vibratory torque, the derivatives of the vibratory angular displacement and the vibratory torque between components at the left end and the right end of the torsional vibration system are derived. The derivatives of the vibratory angular displacement and the vibratory torque are used directly in the Newton-Raphson technique to determine the eigensolutions of systems that are compared and show good agreement with the available data.

Vibration Characteristics of Twin Resonance Tuning-Fork Type Gyro. 1st Report, Method of Fine Tuning for making to High Gain.

Vibratory Rate Gyroscopes have a number of advantages, such as simple structure, stoutness, longlife and quick response, owing to the mechanism of the vibrating body and the absence of the bearings by comparison with the conventional rotating wheel gyro, and are available for a low price angular velocity sensor. However, Coriolis'force with the lower range of angular velocity for sensing is very small, much more the torsional vibration of the suspension mechanism for sensing. Therefore, this paper discribes an experimental study of the mechanical fine tuning for making the higher gain about twin resonance tuning-fork type gyro, and reports on the method of obtaining the resonance to which the torsional vibration system is stabilized.

Resonant frequencies in degeneration of hybrid longitudinal and torsional vibration system

The Langevin vibrator is made of the longitudinal and torsional piezoelectric plates, which can be used for an ultrasonic motor and an ultrasonic welding transducer. Because of the difference between the longitudinal and torsional sound velocity, their resonant frequencies are not equal. To make resonant frequencies of two vibration modes in degeneration, a matching block with a thin neck was connected to the end of the vibrator. Two calculation methods, a dimension network which transmits matrixes and a finite element method have been used. The feasibility of frequencies tuning through a matching block has been analyzed and how to effect the resonant frequency by the radius and thickness of the thin neck and matching block has been summarized. The resonant frequencies of several steel cylinders with variant thin necks and matching blocks were calculated. Some experimental results of measuring the resonant frequencies have been compared with the calculation. According to the calculation and experimental results, a prototype of hybrid longitudinal-torsional ultrasonic motor has been manufactured, and it can be operated very well [Tomikawa et al., IEEE Trans. Ultrason. Ferroelectr. Freq. Control 39 (1992)].

Transmission Conditions of Vibration Stresses to Welding Specimens of Ultrasonic Plastic Welding using Various Two-Vibration-System Equipments

Ultrasonic plastic welding is applied for welding various thermoplastic materials and is widely used in various industrial fields. The two-vibration-system welding method and a high frequency equipment are effective in improving the welding characteristics. A high frequency 90 kHz system can weld plastic sheets under a 1/3 velocity amplitude as compared with that of a low 27 kHz system, but it is difficult to weld large specimens successfully because a high frequency vibration stress cannot be transmitted uniformly due to the stress relaxation effect by the small vibration displacement. To improve the direct welding characteristics, three types of two-vibration-system ultrasonic welding equipments using linear vibration loci of (1) 90 kHz and 27 kHz longitudinal vibration systems, (2) 90 kHz longitudinal and 20 kHz torsional vibration systems, and elliptical vibration loci of (3) 27 kHz complex vibration systems are studied. Transmission conditions of the vibration stresses are measured by pressure sensitive films (Prescale) which are inserted between the plastic sheets. It was shown that a high frequency vibration stress with a small displacement amplitude may be induced uniformly in the welding specimens by combining a low frequency vibration with large displacement amplitude. These welding systems are effectively used to join plastic sheets successfully.

Load characteristics of bolted Langevin torsional transducer II

A torsional vibration system for ultrasonic welding plastics has been assembled and the characteristics demonstrated. The results have been reported in our preceding report [1]. 1.53 ms −1 of the vibration velocity and 90% of the electroacoustical efficiency were obtained using a board radiator connected to the edge of the torsional transducer. However, the region of the acoustic load resistance was too small to get excellent performance as an ultrasonic welding system. In this presentation, we designed and fabricated an angular pillar radiator which was longitudinally connected to the half wavelength straight horn and a bolted Langevin torsional transducer for a torsional vibration system. 95% of the efficiency, 1.61 ms −1 of the vibration velocity and 42 W of the acoustic output power at 18 Ns m −1 of the acoustic load resistance was observed. More than 90% efficiency was also observed in a wide range of acoustic load resistance (10 ~ 93 Ns m −1).

Welding characteristics of ultrasonic plastic welding using two-vibration-system of 90 kHz and 27 or 20 kHz and complex vibration systems

To improve welding characteristics of ultrasonic plastic welding, a 90 kHz two-vibration-system, which can weld plastic sheets under one-third velocity amplitude compared with that of 27 kHz systems, is effective. However, this system cannot weld large specimens successfully because high frequency vibration stress cannot be transmitted uniformly through the large specimens due to the stress relaxation effect by the small vibration displacement of the high frequency welding tip. The ultrasonic welding systems using the combinations of (1) a high frequency 90 kHz longitudinal vibration system with small displacement amplitude and a low frequency 27 kHz longitudinal vibration system with large displacement amplitude (not velocity amplitude), (2) a 90 kHz longitudinal system and a 20 kHz torsional vibration system with large displacement, and (3) the complex vibration welding system using 27 kHz complex vibration welding tips vibrating in elliptical to circular locus are studied. The welding specimens used are soft (polyvinyl chloride: shear vibration loss is large) and hard (polypropylene) sheet materials, and both specimens were welded successfully with smaller velocity amplitude than that of the conventional welding method, similarly in both cases where (1) parallel and (2) normal direction vibration systems are driven simultaneously. The complex vibration welding systems of 27 kHz which has elliptical and circular vibration loci were revealed also effective for plastic welding.

Development of the torque accumulation method for a torsional vibration system

This paper presents a new method to accumulate the output of several torsional transducers together into one output. The torsional transducers are connected around the circumference of a thick metal disk (the accumulator) in which the fundamental torsional mode is excited. The torque of each transducer is transmitted to the accumulator, and the accumulated torque appears on both the top and the bottom surfaces of the accumulator. The authors discuss the torque accumulation and the transformation mechanism analytically by using an equivalent electrical circuit model and obtaining the analytic expression of the torque factor, which represents the maximum output torque per unit voltage applied to the electrical port. In an experimental study, four Langevin torsional transducers 30 mm in diameter attached to an accumulator 100 mm in diameter was used as a prototype. The measured torque factor is found to be proportional to the number of connected transducers, and the calculated torque factor agrees well with the experimentally determined one.

Simple resonance in nonlinear torsional vibration systems of three variable generalized masses

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Characteristics of Two-Vibration-System Ultrasonic Plastic Welding with 90 kHz and 20 kHz Vibration Systems at Right Angles

The direct welding characteristics of an ultrasonic plastic welding system with an upper 90 kHz longitudinal welding tip with a small vibration amplitude and a lower 20 kHz low frequency torsional vibration welding tip with a large vibration amplitude at right angles are studied. By using a combination of high and low vibration frequency systems with small and large vibration amplitude welding tips, the welding characteristics are improved, resulting in a smaller required vibration amplitude and less damage to the specimens due to vibration than those using conventional systems. The two-vibration-system welding equipment consists of a 90 kHz upper longitudinal vibration source with six bolt-clamped Langevin-type piezoelectric ceramic (lead-zircon-titanate; PZT) transducers 15 mm in diameter, a 20 kHz torsional vibration system 40 mm in diameter and a welding frame. The total required velocity amplitude of the two-vibration-system welding equipment is decreased and the welding characteristics are improved significantly compared to those of conventional one-vibration-system for both soft and hard plastic sheet welding.

Load characteristics of a bolted Langevin torsional transducer

Abstract We have proposed before a torsional vibration system for welding plastics. We produced a board radiator to connect it with the edge of the transducer. We measured the load characteristics with this radiator to understand the characteristics of the transducer. However, we did not get a satisfactory result. Now we made a square pillar radiator. We determined the load characteristics using this new radiator. With this measurement, we tried to input about 35 W of electric power in 1.53 m s−1 of vibrating velocity. However, we found that the equivalent mechanical resistance was up to 8 N s m−1.

2-Dimensional Optical Scanner Applying Torsional Resonator with 3 Degrees of Freedom.

A two-dimensional optical scanner suitable for integration in a plane structure has been developed. To make it vibration robust, a torsional vibration system with two degrees of freedom is adopted for the resonator, and the vibration system axis is matched to the center of gravity. Piezoelectric bimorph cells are used as the actuator to excite the torsional vibration. Algorithms of Luh, Walker and Paul, which are usually used for motion analysis of manipulators in robot engineering, were applied for deriving the equations. This optical scanner is capable of optical scanning in two orthogonal directions independently or simultaneously at a scanning angle of ±30 degrees or more. One-dimensional scanning is enabled by driving the bimorph cells with the resonance frequency of either of the two torsional vibrations. Two-dimensional scanning is achieved if the bimorph cells are operated by adding the resonance frequency signals of the two torsional vibrations.