• Journal of the Korean Society for Precision Engineering
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• v.16 no.2 s.95
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• pp.183-193
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• 1999

In the previous study, a module-type vibration analysis system using modular approach is developed for the purpose of analyzing the torsional vibration of vehicle driveline. In the present paper, the system is utilized to investigate the torsional vibration of the driveline of a middle duty truck. The driveline with driving condition is modeled and the torsional vibration response is simulated. The resonance 45Hz is found at engine speed 900rpm and the resultant vibration is very high. It shows favorable agreements with reference data. The effects of parameter change on torsional vibration are also investigated, so it is clarified that clutch characteristics, axle shaft stiffness are very influential on reduction of vibratio. So the countermeasure is proposed for the clutch characteristics. The reduction of torsonal vibration by 8rad/sec is obtained.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.4
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• pp.436-442
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• 2016

This paper presents the torsional vibration isolation performance evaluation of a centrifugal pendulum absorbers (CPAs) that has a continuously varying resonance frequencies proportional to engine firing (excitation) order. CPAs are commonly used to suppress torsional vibrations in rotating machinery and internal combustion engines. In this study, they are employed on the current spring type torsional damper inside a torque converter of automotive vehicle. To evaluate the effectiveness of designed resonance tuning order, the torsional vibration transmissibility based on torque measurements with respect to different engine firing orders is experimentally measured with a lower-inertia dynamometer. The torsional vibration transmissibility with respect to different frequencies with engine order of 2 is also evaluated. It has been demonstrated that the significant vibration reduction over operational frequency range of interest can be achieved by attaching simple pendulums. Future research direction includes the study on theoretical analysis, improved design of pendulum etc.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.946-950
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• 2006

This paper proposed the ways for reduction of the prominent peak of the tone noise in air conditioning units. In order to find out the sources of the tone noise, the resonant frequencies and modes of the fans were investigated. Also, the effects of the ambient temperatures and material properties of the fans on the tone noise were studied. From the experiments, it was shown that the tone noise was greatly influenced by the torsional resonance of the fan and motor system and commutation frequency. In other words, the torsional resonance of the fan and motor system has not to be close to the commutation frequency (torque ripple frequency) which creates a rate of change in the angular acceleration in order to reduce the tone noise in air conditioning units.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.105-111
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• 2008

The clutch with torsional damper is installed on a passenger car with manual transmission, which not only transmits the power generated by engine to the transmission but also absorbs the shock and vibration from the engine. The torsional damper in the clutch dissipates the torsional vibration energy and eliminates the resonance in the driveline but high damping in the damper causes the increase of the vibration level which is against the comfort and durability. In this study, a dynamic model for the passenger car driveline with manual transmission was developed to investigate the vibration and the effects of characteristics of the driveline. With the dynamic model, the vibration characteristics of driveline were examined by the mode analysis and driving simulation, and the effects of hysteresis torque and spring constant were investigated. The vehicle tests with prototype torsional dampers were preformed and the test results showed good agreements with the simulation.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.3
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• pp.243-250
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• 2009

The clutch with torsional damper is installed on a passenger car with manual transmission, which not only transmits the power generated by engine to the transmission but also absorbs the shock and vibration from the engine. The torsional damper in the clutch dissipates the torsional vibration energy and eliminates the resonance in the driveline but high damping in the damper causes the increase of the vibration level which is against the comfort and durability. In this study, a dynamic model for the passenger car driveline with manual transmission was developed to investigate the vibration and the effects of characteristics of the driveline. With the dynamic model, the vibration characteristics of driveline were examined by the mode analysis and driving simulation, and the effects of hysteresis torque and spring constant were investigated. The vehicle tests with prototype torsional dampers were preformed and the test results showed good agreements with the simulation.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.37 no.1
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• pp.10-17
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• 1988

The torsional resonance of the generator shaft system has the possibility of inducing voltages across the stator winding because it is a carrier with the field excitation. And these torsional induced stator currents inducs the eddy current in the rotor. This paper describes the eddy current based on the double Fourier series method. The forces generating during the torsional interaction are computed using the Maxwell's magnetic stress tensor for each of the Fouriercomponennts. And then, these forces of the Fourier components are evaluated by the Parseval's theorem.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1995.10a
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• pp.185-190
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• 1995

In recent years, many researcher have been interested in the stability of a thin beam. Among them, Pai and Nayfeh[1] had investigated the nonplanar motion of the cantilever beam under lateral base excitation and chaotic motion, but this study is associated with internal resonance, i.e. one to one resonance. Also Cusumano[2] had made an experiment on a thin beam, called Elastica, under bending loads. In this experiment, he had shown that there exists out-of-plane motion, involving the bending and the torsional mode. Pak et al.[3] verified the validity of Cusumano's experimental works theoretically and defined the existence of Non-Local Mode(NLM), which is came out due to the instability of torsional mode and the corresponding aspect of motions by using the Normal Modes. Lee[4] studied on a thin beam under bending loads and investigated the routes to chaos by using forcing amplitude as a control parameter. In this paper, we are interested in the motion of a thin beam under torsional loads. Here the form of force based on the natural forcing function is used. Consequently, it is found that small torsional loads result in instability and in case that the forcing amplitude is increasing gradually, the motion appears in the form of dynamic double potential well, finally leads to complex motion. This phenomenon is investigated through the poincare map and time response. We also check that Harmonic Balance Method(H.B.M.) is a suitable tool to calculate the bifurcated modes.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.504-506
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• 1996

In the industrial motor drive systems, a shaft torsional vibration is often generated when a motor and a load are connected with a flexible shaft. This paper treats the vibration suppression control of this system. The resonance ratio control is proposed for suppressing the torsional vibration. In this paper, first, the optimal resonance ratio is sellected and the controller to the resonance ratio controlled outward plant is designed based on $H_{\infty}$ control theory. Secondly, the two-degree-of-freedom controller, which includes the above $H_{\infty}$ controller, is designed in order to improve the tracking characteristics for the commanded speed. The control performances are examined by the computer simulations and it is clarified that the proposed speed control system is useful for two-mass system.

• Korean Journal of Optics and Photonics
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• v.6 no.2
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• pp.165-171
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• 1995

Infrared-Radio frequency double resonance (IRRFDR) and Infrared-Microwave double resonance (IRMWDR) spectroscopy have been used to probe a level of A symmetry for $CD_{3}$OH. Double resonance spectra of $CD_{3}$OH have been investigated over the range of 940 to 1020 $cm ^{-1}$ . Twenty K-type doublet transitions have been observed in both the radio frequency region, which covers 50 MHz to 1 GHz, and the microwave region, which covers 8 GHz to 12 GHz. The results propose new assignments of infrared (IR) absorption transitions and far-infrared (FIR) laser emission lines. These involve torsional excited levels and CO stretch states. Measurements of the A state splitting have permitted the determination of the asymmetry splitting parameters $S^{o}$(n, K) and $^{co}$ (n, K) for (n, K)=(0.3) and (1.3)

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.9
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• pp.667-674
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• 2014

A ship's propulsion shafting system is subjected to varying magnitudes of intermittent loadings that pose great risks such as failure. Consequently, the dynamic characteristic of a propulsion shafting system must be designed to withstand the resonance that occurs during operation. This resonance results from hydrodynamic interaction between the propeller and fluid. For ice-class vessels, this interaction takes place between the propeller and ice. Producing load- and resonance-induced stresses, the propeller-ice interaction is the primary source of excitation, making it a major focus in the design requirements of propulsion shafting systems. This paper examines the transient torsional vibration response of the propulsion shafting system of an ice-class research vessel. The propulsion train is composed of an electric motor, flexible coupling, spherical gears, and a propeller configuration. In this paper, the theoretical analysis of transient torsional vibration and propeller-ice interaction loading is first discussed, followed by an explanation of the actual transient torsional vibration measurements. Measurement data for the analysis were compared with an applied estimation factor for the propulsion shafting design torque limit, and they were evaluated using an existing international standard. Addressing the transient torsional vibration of a propulsion shafting system with an electric motor, this paper also illustrates the influence of flexible coupling stiffness design on resulting resonance. Lastly, the paper concludes with a proposal to further study the existence of negative torque on a gear train and its overall effect on propulsion shafting systems.