• Structural Engineering and Mechanics
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• v.55 no.4
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• pp.839-856
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• 2015

A multi-contact tooth meshing model for helical gear pairs considering bearing and shaft deformations is proposed. First, to easily incorporate into the system model, the complicated Harris' bearing force-displacement relationship is simplified applying a linear least square curve fit. Then, effects of shaft and bearing flexibilities on the helical gear meshing behavior are implemented through transformation matrices which contain the helical gear orientation and spatial displacement under loads. Finally, true contact lines between conjugated teeth are approximated applying a modified meshing equation that includes the influence of tooth flank displacement on the tooth contact induced by shaft and bearing displacements. Based on the model, the bearing's force-displacement relation is examined, and the effects of shaft deformation and external load on the multi-contact tooth mesh load distribution are also analyzed. The advantage of this work is, unlike previous works to search true contact lines through time-consuming iterative strategy, to determine true contact lines between conjugated teeth directly with presentation of deformations of bearings and shafts.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.1
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• pp.29-35
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• 2013

The pitch reducer consists of several planetary gearsets, and they should have good load distribution over gear tooth flank and load sharing among the planets to improve the durability. This work investigates how bearing internal clearances influence both the load distribution over the gear tooth flank and the planet load sharing. A whole system model is developed to analyze a pitch reducer. The model includes non-linear mesh stiffness of gears, non-linear stiffness of bearings. The results indicate that the face load factor and mesh load factor decrease, and the fatigue life of output shaft bearings increase as bearing internal clearances of output shaft decrease. Therefore, the internal clearance of output shaft bearing must be considered when designing the pitch reducer for wind turbines.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.5
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• pp.8-14
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• 2014

A slewing reducer consists of two planetary gearsets which require a good load distribution over the gear tooth flank for enhanced durability. This work investigates how the bearing characteristics influence the load distribution over the gear tooth flank. A complete system model is developed to analyze a slewing reducer, including the non-linear mesh stiffness of the gears and the non-linear stiffness of bearings. The results indicate that the type, arrangement and preload of the output shaft bearings greatly influence the gear mesh misalignment, contact pattern, face load factor, gear safety factor and lifetimes of the parts.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.4
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• pp.70-75
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• 2011

Nowadays, modern gearboxes are characterized by high torque load demands, low running noise and compact design. Also durability of gearbox is specially a major issue for the industry. For the gearbox which used in wind turbine, gear transmission error(T.E.) is the excitation that leads the tonal noise known as gear whine, and radiated gear whine is also the dominant source of noise in the whole gearbox. In this paper, tooth modification for the high speed stage is used to compensate for the deformation of the teeth due to load and to ensure a proper meshing to achieve an optimized tooth contact pattern. The gearbox is firstly modeled in Romax software, and then the various combination analysis of the tooth modification is presented by using Windows LDP software, and the prediction of transmission error under the loaded torque for the helical gear pair is investigated, the transmission error, contact stress, root stress and load distribution are also calculated and compared before and after tooth modification under one torque condition. The simulation result shows that the transmission error and stress under the loads can be minimized by the appropriate tooth modification.

• Structural Engineering and Mechanics
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• v.43 no.4
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• pp.439-448
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• 2012

This paper investigates the load sharing of double circular arc helical gears considering the influence of assembly errors. Based on a load sharing formulae, a three-dimensional finite element tooth contact analysis (TCA) is implemented with commercial software package ANSYS. The finite element grid for the double circular arc gear contact model is automatically generated by using the APDL (ANSYS Parameter Design Language) embedded in ANSYS. The realistic rotation of gears is achieved by using a coupling degree-of-freedom method. Numerical simulations are carried out to exemplify the proposed approach. The distribution of contact stress and bending stress under specific loading conditions are computed and compared with those obtained from Hertz contact theory and empirical formulae to demonstrate the efficiency of the proposed load sharing calculation formulae and TCA approach.

• Restorative Dentistry and Endodontics
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• v.19 no.2
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• pp.384-408
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• 1994

The purpose of this study was to evaluate the fracture resistance of tooth restored with gold inlay. A profound understanding of the isthmus width factor, which is one of the several parameters of cavity designs, would facilitate the appropriate cavity preparation in a specific clinical situation. In this study, the cavities for gold inlay were prepared in maxillary left first premolar. A three-dimensional model was designed using I-DEAS program. The model was composed of 2515- nodes and 2172 isoparametric brick elements. In the model isthmus width was varied into 1/4, 1/3 and 1/2 of intercuspal width respectively, and numeric values of the material properties of enamel, dentin and gold was set. Three types of load : concentrated load, divided load and distributed load was 500N. The empty cavities in the model were also examined using divided load and distributed load. The three - dimensional Finite Element Method was used to analysis the displacement and stress distribution. The results were as follows : 1. All of the experimental models which were filled with gold inlay revealed similar direction of displacement to that of the natural tooth model under the same load type. But in the models with empty cavities, as the isthmus width increased, the degree of displacement increased in the case of divided load type. 2. All experimental models which were filled with gold inlay showed stress concentration at load points, but in the models with empty cavities at divided load type, as isthmus width increased, stress was concentrated at the comer of the pulpal floor. 3. In the models with empty cavities at divided load type, tooth fracture was expected regardless of isthmus width, but all experimental models which were filled with gold inlay after cavity preparation were not susceptible to fracture. 4. In all experimental models which were filled with gold inlay after cavity preparation, displacement patterns were similar under both concentrated and divided load types. In the models with empty cavities, a divided load resulted in a bucco-lingual cuspal displacemenat in both sides, but a distributed load resulted in a lingual displacement of the tooth.

• The Journal of Korean Academy of Prosthodontics
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• v.29 no.3
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• pp.1-32
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• 1991

Tho osseointegrated dental prosthetic treatment has develped for the edentulous patient with severely resorbed alveolar ridge, and has given us a successful clinical results to date. Nowadays the partially edentulism is included among the indications of the osseointegrated prosthetic treatment. The purpose of this study was to analyze the stress distribution at supporting bone according to the types of connection modality between implant and tooth in the superstructure. Two dimensional finite element stress analysis was applied for this study. FEM models were created using software Super SAP for MBM 16bit personal computer. Three modalities of connection were modeled and analyzed under load condition. The results were as follws: 1. The stress develped at tooth and implant in the cancellous bone was lower in the case of rigid connection than in the case of norigid connection, but higher between the two implants in the case of rigid connection than in the case of nonrigid connection. 2. The stress developed at the cortical bone and at the supporting bone interface was lower in the case of rigid connection than in the case of nonrigid connection 3. The stress developed at the supporting tissue interface of the implant nearby the tooth, was lower in the case of rigid connection than in the case of nonrigid connection. 4. The stress developed at the supporting tissue interface of posteriormost implant, was same between the cases of rigid and nonrigid connection. 5. The stress distribution related to the freestanding case was generally similar to the stress distribution pattern of nonrigid connection case. 6. The magnitude of applied load which produces deformation within elastic limit, had influence on the absolute value of stress, but had no influence on the pattern of stress distribution of the same case.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.5
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• pp.66-72
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• 2016

Gearboxes are mechanical components that transmit power by adjusting input and output speed and torque. Their design requirements include small size, light weight, and long lifespan. We have investigated the effects of carrier pinhole position error on the load sharing and load distribution characteristics of a planetary gear set with four planet gears. The simulation model for a simple planetary gear set was developed and verified by comparing analytical results with a putative model. Then, we derived the load sharing and load distribution characteristics under various pinhole position error conditions using the prototypical simulation model. The results showed that the mesh load factor and face load factor increased with the pinhole position error, which then influenced the safety factor for tooth bending strength and surface durability.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.816-819
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• 2002

This paper is the study on stress analysis for tooth modification of high speed gear using a finite element method. Gear drives constitute very important mechanisms in transmitting mechanical power processes compromising several cost effective and engineering advantages. The load transmission occurred by the contacting surfaces arises variable elastic deformations which are being evaluated through finite element analysis. The automatic gear design program is developed to model gear shape precisely. This gear design system developed was used by pre-processor of FEM packages. The distribution of stresses at contacting surfaces was examined when gear tooth contacts. And this paper proposes method for the tooth modification after carrying out stress analysis using a finite element method.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.2
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• pp.162-167
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• 2003

This paper is the study on stress analysis for tooth modification of high speed gear using a finite element method. Gear drives constitute very important mechanisms in transmitting mechanical power processes which compromise several cost effective and engineering advantages. The load transmission which occurred by the contacting surfaces arises variable elastic deformations evaluated through finite element analysis. The automatic gear design program was developed to model gear shape precisely. This developed gear design system was used by pre-processor of FEM packages. The distribution of stresses at contacting surfaces was examined when gear tooth contacts. And this paper proposes a method for the tooth modification after carrying out stress analysis using a finite element method.