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Gordana Marunić - One of the best experts on this subject based on the ideXlab platform.
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Location of Spur Gear Maximum Tooth Root Stress
2020Co-Authors: Gordana Marunić, Vladimir Glažar, Goran GregovAbstract:The paper deals with the analysis of maximum Tooth Root stress location for external spur solid and thin-rimmed gear. The Locations of maximum Tooth Root stress are determined based on the 3D FEM calculations, and investigated in relation of thr appearnce at the Tooth fillet and along the face width. The comparison of results is performed with the critical Tooth Root section that is for stress calculation proposed by analytical methods.
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Effect of Load Distribution along Facewidth on Tooth-Root Stress
2020Co-Authors: Gordana MarunićAbstract:The paper deals with the effect of non-uniform load distribution along spur Tooth facewidth, upon a Tooth-Root stress field of thin-rimmed gear. The different linear load distribution, from constant load to triangular shape, is simulated by the boundary conditions imposed to the developed 3D FEM single gear models. The combined influence of a gear rim thickness and the facewidth upon the Tooth-Root stress distribution is investigated. Based upon the established Tooth-Root stress distribution of thin-rimmed gear, the ratio between maximum Tooth-Root stress for certain load distribution, and mean Tooth-Root stress along the facewidth for constant load distribution, is estimated. This ratio corresponds to the face load factor of the standard ISO, proposed for the gears with a minimum rim thickness of sR>3, 5m.
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Gear Tooth-Root Stress of Single Pair Contact
2020Co-Authors: Gordana MarunićAbstract:Based upon the developed complex pinion-wheel 3D FEM numerical model, the Tooth-Root stress was determined of spur gear for the meshing phase. The obtained results pointed to maximum stress magnitude reached for the single pair Tooth contact, and these fillet stresses have been analysed in this paper, related to the gear geometrical parameters taken into account. The Tooth Root stress was determined for the gear, which can be considered as narrow and wider faced one. As the fillet stress behaviour is strongly influenced by the rim thickness, there have been considered solid and thin-rimmed gear. These parameters, the Tooth facewidth and the rim thickness, have been followed for the gears of different geometry determined by fewer and larger number of teeth. Equivalent von Mises stress was determined along with maximum tangential stress component on tensile side of the loaded Tooth Root, and the comparison with nominal bending stress according to the ISO calculation procedure was accomplished.
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Effects of Gear Teeth Support upon Tooth-Root Stress Longitudinal Distribution
2020Co-Authors: Gordana MarunićAbstract:The paper deals with the three-dimensional FEM stress analysis of spur thin-rimmed gears with different blank structures. The Tooth-Root longitudinal stress distribution has been established of thin-rimmed gear without and with web, and for the sake of comparison, of a solid gear. The Tooth-Root stresses have been separated and analysed for the engagement position at the outer point of single pair Tooth contact. In the case of thin-rimmed gear with web, two gear blank structures have been considered: middle and end web position. The correlation between the effects of a Tooth support rigidity determined by the chosen gear blank structure and the Tooth-Root stress have been presented. The stress results have been shown as a function of thin rim thickness and related to the stress values of a solid gear. The obtained conclusions about Tooth-Root stress behavior offer some useful information for the buildup of gear.
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Spur Tooth-Root Maximum Stress of Meshing Phase
2020Co-Authors: Gordana MarunićAbstract:By means of 3D FEM calculation, the Root stress of standard spur gear Tooth has been determined. The developed numerical pinion-gear model enabled the simulation of actual load sharing between two teeth in contact, and the change of Tooth-Root stress has been observed for the change of meshing phase. Related to the gear geometry (number of teeth, rim thickness, Tooth facewidth) the points of meshing phase have been selected where maximum Tooth-Root stress is reached. These values of tangential stress component and equivalent von Mises stress have been related to the stress value according to ISO 6336-3 standard procedure.
Yang Chai - One of the best experts on this subject based on the ideXlab platform.
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cellular and molecular mechanisms of Tooth Root development
Development, 2017Co-Authors: Jingyuan Li, Carolina Parada, Yang ChaiAbstract:The Tooth Root is an integral, functionally important part of our dentition. The formation of a functional Root depends on epithelial-mesenchymal interactions and integration of the Root with the jaw bone, blood supply and nerve innervations. The Root development process therefore offers an attractive model for investigating organogenesis. Understanding how Roots develop and how they can be bioengineered is also of great interest in the field of regenerative medicine. Here, we discuss recent advances in understanding the cellular and molecular mechanisms underlying Tooth Root formation. We review the function of cellular structure and components such as Hertwig's epithelial Root sheath, cranial neural crest cells and stem cells residing in developing and adult teeth. We also highlight how complex signaling networks together with multiple transcription factors mediate tissue-tissue interactions that guide Root development. Finally, we discuss the possible role of stem cells in establishing the crown-to-Root transition, and provide an overview of Root malformations and diseases in humans.
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an nfic hedgehog signaling cascade regulates Tooth Root development
Development, 2015Co-Authors: Jifan Feng, Jingyuan Li, Hu Zhao, Thachvu Ho, Yang ChaiAbstract:Coordination between the Hertwig9s epithelial Root sheath (HERS) and apical papilla (AP) is crucial for proper Tooth Root development. The hedgehog (Hh) signaling pathway and Nfic are both involved in Tooth Root development; however, their relationship has yet to be elucidated. Here, we establish a timecourse of mouse molar Root development by histological staining of sections, and we demonstrate that Hh signaling is active before and during Root development in the AP and HERS using Gli1 reporter mice. The proper pattern of Hh signaling activity in the AP is crucial for the proliferation of dental mesenchymal cells, because either inhibition with Hh inhibitors or constitutive activation of Hh signaling activity in transgenic mice leads to decreased proliferation in the AP and shorter Roots. Moreover, Hh activity is elevated in Nfic −/− mice, a Root defect model, whereas RNA sequencing and in situ hybridization show that the Hh attenuator Hhip is downregulated. ChIP and RNAscope analyses suggest that Nfic binds to the promoter region of Hhip . Treatment of Nfic −/− mice with Hh inhibitor partially restores cell proliferation, AP growth and Root development. Taken together, our results demonstrate that an Nfic - Hhip -Hh signaling pathway is crucial for apical papilla growth and proper Root formation. This discovery provides insight into the molecular mechanisms regulating Tooth Root development.
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fate of hers during Tooth Root development
Developmental Biology, 2009Co-Authors: Pablo Bringas, Xiaofeng Huang, Harold C Slavkin, Yang ChaiAbstract:Tooth Root development begins after the completion of crown formation in mammals. Previous studies have shown that Hertwig's epithelial Root sheath (HERS) plays an important role in Root development, but the fate of HERS has remained unknown. In order to investigate the morphological fate and analyze the dynamic movement of HERS cells in vivo, we generated K14-Cre;R26R mice. HERS cells are detectable on the surface of the Root throughout Root formation and do not disappear. Most of the HERS cells are attached to the surface of the cementum, and others separate to become the epithelial rest of Malassez. HERS cells secrete extracellular matrix components onto the surface of the dentin before dental follicle cells penetrate the HERS network to contact dentin. HERS cells also participate in the cementum development and may differentiate into cementocytes. During Root development, the HERS is not interrupted, and instead the HERS cells continue to communicate with each other through the network structure. Furthermore, HERS cells interact with cranial neural crest derived mesenchyme to guide Root development. Taken together, the network of HERS cells is crucial for Tooth Root development.
José I. Pedrero - One of the best experts on this subject based on the ideXlab platform.
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Tooth-Root stress calculation of high transverse contact ratio spur and helical gears
Meccanica, 2014Co-Authors: Miryam B. Sánchez, Miguel Pleguezuelos, José I. PedreroAbstract:In this paper, a non-uniform model of load distribution along the line of contact of spur and helical gears, obtained from the minimum elastic potential criterion, has been used, combined with the equations of the linear elasticity, to evaluate the Tooth-Root stress of high transverse contact ratio gears. The values of both critical stress and load conditions have been obtained and a complete analysis of the Tooth bending strength has been carried out. As the load per unit of length at any point of the line of contact and any position of the meshing cycle has been described by a very simple equation, a complete study of the location and the value of the Tooth-Root stress has been carried out. From this study, a recommendation for the calculation of the bending load capacity of high transverse contact ratio spur and helical gears is proposed.
Richard M Gronostajski - One of the best experts on this subject based on the ideXlab platform.
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essential role for nfi c ctf transcription replication factor in Tooth Root development
Molecular and Cellular Biology, 2003Co-Authors: George Steeleperkins, Kenneth G Butz, Gary E Lyons, Margarita Zeichnerdavid, Richard M GronostajskiAbstract:The mammalian Tooth forms by a series of reciprocal epithelial-mesenchymal interactions. Although several signaling pathways and transcription factors have been implicated in regulating molar crown development, relatively little is known about the regulation of Root development. Four genes encoding nuclear factor I (NFI) transcription-replication proteins are present in the mouse genome: Nfia, Nfib, Nfic, and Nfix. In order to elucidate its physiological role(s), we disrupted the Nfic gene in mice. Heterozygous animals appear normal, whereas Nfic−/− mice have unique Tooth pathologies: molars lacking Roots, thin and brittle mandibular incisors, and weakened abnormal maxillary incisors. Feeding in Nfic−/− mice is impaired, resulting in severe runting and premature death of mice reared on standard laboratory chow. However, a soft-dough diet mitigates the feeding impairment and maintains viability. Although Nfic is expressed in many organ systems, including the developing Tooth, the Tooth Root development defects were the prominent phenotype. Indeed, molar crown development is normal, and well-nourished Nfic−/− animals are fertile and can live as long as their wild-type littermates. The Nfic mutation is the first mutation described that affects primarily Tooth Root formation and should greatly aid our understanding of postnatal Tooth development.
Zaigang Chen - One of the best experts on this subject based on the ideXlab platform.
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improved analytical methods for calculation of gear Tooth fillet foundation stiffness with Tooth Root crack
Engineering Failure Analysis, 2017Co-Authors: Zaigang Chen, Jie Zhang, Wanming Zhai, Yawen WangAbstract:Abstract Two improved analytical calculation models of gear Tooth fillet-foundation stiffness are proposed for spur gears with Tooth Root crack. The proposed two models are capable of taking Tooth Root crack into account in the calculation of gear Tooth fillet-foundation stiffness. For Model-1, the reduction of gear Tooth fillet-foundation stiffness is assumed to be the production of the stiffness under healthy condition and the ratio of the crack length to the Tooth thickness along the potential crack path. While in Model-2, the stiffness of the gear Tooth fillet-foundation is calculated by updating related geometrical parameters in the traditional calculation formulas for the healthy gears according to the variation of the load carrying zone due to Tooth Root crack. The two calculation models for calculating the Tooth fillet-foundation stiffness of cracked gears are verified by the finite element method (FEM). The results show that model-1 has a relatively poor accuracy for large crack cases when the position of applied force is close to the Tooth Root, while model-2 has a higher accuracy for both small and large crack length. The proposed models can be employed to improve the accuracy of gear mesh stiffness calculation and assist gear faults detection and diagnosis.
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dynamic features of planetary gear set with Tooth plastic inclination deformation due to Tooth Root crack
Nonlinear Dynamics, 2013Co-Authors: Yimin Shao, Zaigang ChenAbstract:Gear Tooth Root crack, as one of the popular gear Tooth failures, is always caused by the dynamic load or excessive load applied to the Tooth. It will devastate the working performance of the gear system, by problems such as vibration and noise, or even lead to a broken Tooth, which will stop the normal working process of the gear system. It has attracted wide attention from researchers. However, the previous studies focused their concentration only on the mesh stiffness reduction due to Tooth Root crack, while the Tooth plastic inclination due to Tooth bending damages like gear Tooth Root crack is seldom considered. In this paper, a Tooth plastic inclination model for spur gear with Tooth Root crack is developed by regarding the cracked Tooth as a cantilever beam. It influences not only the displacement excitation but also the mesh stiffness and load-sharing factor among Tooth pairs in mesh. The simulation results obtained by incorporating the Tooth plastic inclination deformation model together with the Tooth Root crack model into a 21-Degree-of-Freedom planetary gear dynamic model indicate that the Tooth plastic inclination has a significant effect on the performance of the gear system rather than the mesh stiffness reduction due to Tooth Root crack.
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dynamic simulation of planetary gear with Tooth Root crack in ring gear
Engineering Failure Analysis, 2013Co-Authors: Zaigang Chen, Yimin ShaoAbstract:Abstract Planetary gear is widely used in different areas due to its advantages such as compactness, large torque-to-weight ratio, large transmission ratios, reduced noise and vibrations. However, the Tooth faults like cracks are seldom concentrated. In this paper, a mesh stiffness model of internal gear pair with a Tooth Root crack in the ring gear is derived based on the potential energy principle. The mesh stiffness model is incorporated into the dynamic model of a one-stage planetary gear set with 21-degree-of-freedom (DOF) to investigate the effect of the internal gear Tooth Root crack. The crack cases with different dimensions are designed in this paper to demonstrate their influences on the mesh stiffness and the dynamic performance of the planetary gear set. The simulated results show that bigger reduction in mesh stiffness is caused by the growth in the crack size. And the impulsive vibrations and sidebands can be observed in the dynamic response of the planetary gear set in time and frequency domains, respectively. Both their amplitudes increase as the crack propagation which supply the possibility for them to be the indicators in the condition monitoring and fault diagnosis of planetary gear system.
