• The korean journal of orthodontics
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• v.30 no.4 s.81
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• pp.467-473
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• 2000

As a rectangular wire Is inserted into edgewise brackets the wire exerts a force system three-dimensionally. The force system may include bending force in first and second orders and a torsional force in third order Analytical and experimental studies on bending force have been Introduced, but information about torsion is still lack. The purpose of this study was to estimate the torsional moment in the force system of rectangular arch wires through theoretical and experimental studies. Wires most frequently used for third order control were selected as study materials. Cross sections of 0.016x0.022, 0.017x0.025, 0.019x0.025 inch rectangular wires in foot different materials such as stainless steel(Ormco), TMA(Ormco), NiTi(Ormco), and braided stainless steel (DentaFlex, Dentaurum) were used. The torque/twist rate of each test material was calculated using the torsion formula. Torque/twist rate, yield torsional moment, and ultimate torsional moment were measured with a torque gauge. The torsion formula assesses that the torque/twist rate (T/$\theta$) is proportional to the characteristics of material (G) and cross section (J), and is inversely proportional to the length of wire (L). Most experimental results corresponded with the formula. The relative stiffness was calculated for reference to a logical sequence of wire changes.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.6 no.3
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• pp.96-102
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• 1997

Eigenvalue analysis of vibration mode and an analysis by frequency response among the methods of predicting gear noise are related with transmitting sound of vibration. In this study we intended to reduce the vibration noise of differential gear by reducing torque fluctuation of drive pinion shaft which causes vibration noise of differential gear in rear wheel drive vehicles. For this we developed multi-degree of freedom analysis model in which mass moment of inertia and torsional spring combined and we examined the influence of torsional vibration of driveline elements by performing forced vibration analysis of engine excitation torque. We studied the methods for reducing torsional vibration of driveline according to the design factor of propeller shaft and examined the effects reducing vibration in differential gear by applying flexible coupling.

• The korean journal of orthodontics
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• v.31 no.3 s.86
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• pp.335-346
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• 2001

The purpose of this study was to investigate the ideal clinical torque(In the SWA rectangular wire, the torque by the angle between the plane part and twisted part to move the tooth) of the orthodontic rectangular wire which produce the proper labiolingual movement of the single tooth during finishing stage of the orthodontic treatment. The clinical torque is the sum of the play and the active torque which generates the moment at the bracket. The play is calculated by the formula and the active torque is calculated by the computer aided three-dimensional finite element method. The finite element model was consist of the three brackets which formed a row and 3 kinds of orthodontic rectangular wire(stainless steel, TMA, NiTi) which inserted in brackets. Both sides of the model were twisted and the moment generated in the center bracket was calculated. The sizes of seven wires which were used commonly were .016'X.022', .017'X.022', .017'X.025', .018'X.025', .019'X.025', .020'X.025', .021'X.025'. In 018' bracket, 016'X.022', .017'X.022', .017'X.025' wires were inserted and in 022' bracket, all the sizes of wires except .016'X.022' were inserted and tested. The following conclusions could be drawn from this study. 1. The moments generated on the same size of the wires by the same active torque were equal regardless of the bracket slot size. 2. The moments were increased with the size of the wires. The moment generated on the .021'X.025' wire was about 1.75 times as large as that on the .016'X.022' wire regardless of the material. 3. The moments were increased in the order of the NiTi, TMA stainless steel. The moment of the TMA wire was 0.35 times as small as that of the stainless steel wire and the moment of the NiTi was0.16 times as small as that of the stainless steel wire. 4. The moment was decreased as the interbracket distance was increased. 5. To get a desired moment with the specific size and material of the wire on the specific bracket slot, the formula and the results were displayed.

• Journal of KSNVE
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• v.7 no.5
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• pp.853-860
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• 1997

For this study, the multi-degree of freedom analysis model of torsional vibration was developed. This model is combined with mass moment of inertia and torsional spring in two wheel drive and four wheel drive vehicle. We compared and analyzed torsional vibration characteristics by natural frequencies and mode shapes which are obtained by free vibration analysis of this model. And we studied torsional vibration contribution of driveline elements by performing the forced vibration analysis of engine excitation torque. The validity of this model is demonstrated by the field test. The reduction effect of the torsional vibration along the driveline design factor is presented by the analytical results.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.7
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• pp.221-228
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• 1999

A full-time four wheel drive vehicle is driven literally full time by the front and the rear wheels. Front and rear drive shafts are rotated rapidly in the extremely torsional state, which can cause various vibration and noise problems. The purpose of this study is to reduce the vibration and the noise of the full -time four wheel drive vehicle. In this paper, both the causes and the methods for reduction of torsional vibration are suggested. For this study, the characteristics of the torsional vibration are analyzed by free and forced torsional vibration simulation. And this paper described the influence upon the torsional vibration with emphasis shafting system. The validity of simulation models is checked by the field test. The forced vibration simulation with the variations of shaft design factors are performed by the checked models. According to the simulation , the resonance region shifts and the torque fluctuation varies in the system,. Finally, the methods and the effects for the torsional vibration reduction in driveline are proposed.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1997.10a
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• pp.316-321
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• 1997

The purpose of this study is to reduce the vibration noise of differential gear by reducing torque fluctuation of drive pinion shaft which causes vibration noise of differential gear in rear wheel drive vehicles. For this we developed multi-degree of freedom analysis model in which mass moment of inertia and torsional spring combined, the validity of the simulation model was checked by the field test and we examined the influence of torsional vibration of driveline elements by performing forced vibration analysis of engine excitation torque. We studied the methods for reducing torsional vibration of driveline according to the design factor of propeller shaft and examined the effects reducing vibration differential gear by applying flexible coupling.

• Structural Engineering and Mechanics
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• v.67 no.4
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• pp.391-401
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• 2018

Locally available Stainless Steel Wire Mesh (SSWM) bonded on a concrete surface with an epoxy resin is explored as an alternative method for the torsional strengthening of Reinforced Concrete (RC) beam in the present study. An experiment is conducted to understand the behavior of RC beams strengthened with a different configuration of SSWM wrapping subjected to pure torsion. The experimental investigation comprises of testing fourteen RC beams with cross section of $150mm{\times}150mm$ and length 1300 mm. The beams are reinforced with 4-10 mm diameter longitudinal bars and 2 leg-8 mm diameter stirrups at 150 mm c/c. Two beams without SSWM strengthening are used as control specimens and twelve beams are externally strengthened by six different SSWM wrapping configurations. The torsional moment and twist at first crack and at an ultimate stage as well as torque-twist behavior of SSWM strengthened specimens are compared with control specimens. Also the failure modes of the beams are observed. The rectangular beams strengthened with corner and diagonal strip wrapping configuration exhibited better enhancement in torsional capacity compared to other wrapping configurations. The numerical simulation of SSWM strengthened RC beam under pure torsion is carried out using finite element based software ABAQUS. Results of nonlinear finite element analysis are found in good agreement with experimental results.

• Structural Engineering and Mechanics
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• v.47 no.2
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• pp.247-263
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• 2013

It is evident that torsional resistance of a reinforced concrete (RC) member is attributed to both concrete and steel reinforcement. However, recent structural design codes neglect the contribution of concrete because of cracking. This paper reports on the results of an experimental and numerical investigation into the torsional capacity of concrete beams reinforced only by longitudinal rebars without transverse reinforcement. The experimental investigation involves six specimens tested under pure torsion. Each specimen was made using a cast-in-place concrete with different amounts of longitudinal reinforcements. To create the torsional moment, an eccentric load was applied at the end of the beam whereas the other end was fixed against twist, vertical, and transverse displacement. The experimental results were also compared with the results obtained from the nonlinear finite element analysis performed in ANSYS. The outcomes showed a good agreement between experimental and numerical investigation, indicating the capability of numerical analysis in predicting the torsional capacity of RC beams. Both experimental and numerical results showed a considerable torsional post-cracking resistance in high twist angle in test specimen. This post-cracking resistance is neglected in torsional design of RC members. This strength could be considered in the design of RC members subjected to torsion forces, leading to a more economical and precise design.

• The korean journal of orthodontics
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• v.33 no.2 s.97
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• pp.131-140
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• 2003

The purpose of this study was to evaluate clinical applications of electroplating method through investigation of the physical properties of orthodontic rectangular wires according to varying their cross section. For the study, it was accomplished to electroplate the 0.016-inched orthodontic rectangular stainless steel wire. The cross section of stainless steel orthodontic rectangular wire increased from $0.016{\times}0.016inch\;to\;0.017{times}0.017inch$ by electroplating. The wire was heat treated to improve an adhesion between the wire and electroplated metal. h three-point bending test and torsion test were conducted in order to compare physical properties among three wire groups; $0.016{\times}0.016wires(group 016),\; electroplated\;0.016{\times}0.016wires(group\;016P)\;and\;0.017{\times}0.017$ wires (group 017). Through the investigations of each wire group, following results were obtained 1. At three-point bending test, the group Ol6P showed higher tendency in the degree of stiffness, yield strength and ultimate tensile strength than the group 016. Stiffness and ultimate tensile strength showed statistically significant differences between two groups at three-point bending test (p<0.05). 2. Stiffness, yield strength, and ultimate tensile strength of the group 016P showed lower tendency than those of the group 017 Stiffness showed statistically significant differences between two groups at three-point bending test (p<0.05). 3. Torque/twist rate, yield torsional moment, and ultimate torsional moment of the group 016P showed higher tendency than those of the group 016. All measurements showed statistically significant differences between two groups alter torsion test (p<0.05). 4. Torque/twist rate, yield torsional moment, and ultimate torsional moment of the group 0166P showed lower tendency than those of the group 017. Yield torsional moment, and ultimate torsional moment showed statistically significant differences between two groups after torsion test (p<0.05).

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.411-416
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• 2005

Nowadays, diesel power plant using low speed two stroke diesel engine is widely used in islands and restricted areas. Considerations were given to its benefit of high thermal efficiency, reliability and durability compared to the other prime movers. However, various types of engine vibration affect neighboring buildings to their structural vibration. For this, diesel power plant are held liable for the troubles caused by these vibration. These are mainly due to the X- and H-type engine vibrations which we excited by the X- and H- guide force moment. Authors have identified a structural vibration of new pattern called ‘T-mode vibration’ due to the torsional vibration of shafting system. In this paper, T-mode vibration is analyzed through an experimental method based on the global vibration measurement.