Paper IV (iv) Modification of the Two-Body Contact Conditions to Account for the third Body

Author(s):  
J.J. Kalker
Author(s):  
David Richard ◽  
Mathieu Renouf ◽  
Yves Berthier ◽  
Ivan Iordanoff

The objective of this paper is to highlight the influence of the rheology of a third body in dry sliding contact conditions. It has been shown that the local cohesion of the third body can create an asymmetric dissipative field through its thickness. The present study puts forward the consequences from a thermal point of view, overcoming the inherent experimental difficulties at this microscopic scale.


Author(s):  
B. J. Briscoe ◽  
S. K. Sinha

This paper reviews some of the recent progress which has been made in the area of the sliding wear of polymers. Wear mechanisms are classified under three broad approaches which reflect primarily the way this subject has been historically studied. It is demonstrated here that the wear of polymers is influenced by the contact conditions, the bulk mechanical properties of the polymer and the properties of the ‘third body’, which generally appears in the form of transfer film or degraded polymer particles between two sliding surfaces. Further, this paper establishes a link between the different contact and material parameters and shows how they are important in elucidating the generic wear mechanisms for polymers. The effects of environment and lubrication upon polymer wear are briefly explained in terms of the chemical interactions between the liquid phase and the polymer. The capabilities and limitations of current predictive wear models for polymeric contacts are also highlighted.


2021 ◽  
Vol 133 (3) ◽  
Author(s):  
Marilena Di Carlo ◽  
Simão da Graça Marto ◽  
Massimiliano Vasile

AbstractThis paper presents a collection of analytical formulae that can be used in the long-term propagation of the motion of a spacecraft subject to low-thrust acceleration and orbital perturbations. The paper considers accelerations due to: a low-thrust profile following an inverse square law, gravity perturbations due to the central body gravity field and the third-body gravitational perturbation. The analytical formulae are expressed in terms of non-singular equinoctial elements. The formulae for the third-body gravitational perturbation have been obtained starting from equations for the third-body potential already available in the literature. However, the final analytical formulae for the variation of the equinoctial orbital elements are a novel derivation. The results are validated, for different orbital regimes, using high-precision numerical orbit propagators.


2002 ◽  
Vol 11 (3) ◽  
pp. 288-293 ◽  
Author(s):  
Gui-Zhen Xu ◽  
Jia-Jun Liu ◽  
Zhong-Rong Zhou

1999 ◽  
Author(s):  
Markus A. Wimmer

Abstract Third-body wear is a frequently reported phenomenon in TKR, however, little attention has been paid to the load carrying capacity of third bodies. It may be possible that these particles accumulate to a quantity, sufficient to separate the articulating surfaces of the bearing. To address this question, the particle number for a complete separation was theoretically determined and compared to realistic values. Based on the results, a total separation of the artificial knee articulation appears likely and should be considered when interpreting surface wear based on common stress analyses. This seems to be reflected by clinical observation that flat tibial components do not wear faster than dished ones.


2017 ◽  
Vol 23 (3) ◽  
pp. 420-432 ◽  
Author(s):  
Pavel Krejčí ◽  
Adrien Petrov

The third-body concept is a pragmatic tool used to understand the friction and wear of sliding materials. The wear particles play a crucial role in this approach and constitute the main part of the third-body. This paper aims to introduce a mathematical model for the motion of a third-body interface separating two surfaces in contact. This model is written in accordance with the formalism of hysteresis operators as solution operators of the underlying variational inequalities. The existence result for this dynamical problem is obtained by using a priori estimates established for Faedo–Galerkin approximations, and some more specific techniques such as anisotropic Sobolev embedding theory.


2015 ◽  
Vol 16 (25) ◽  
pp. 168
Author(s):  
Vilma Moreira dos Santos ◽  
Thiago Veloso Vitral ◽  
Alessandra Palhares

<p>O Projeto <strong>Memorial da Imprensa de Uberaba: criação da Hemeroteca Digital do Triângulo Mineiro e Alto Paranaíba </strong>constitui, provavelmente, o maior investimento do estado de Minas Gerais em um projeto individual na área de preservação de acervos documentais históricos. O projeto conta com o financiamento da Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG). Foi concebido e vem sendo executado por parceria firmada entre a Secretaria de Estado de Ciência, Tecnologia e Ensino Superior (SECTES/MG) e a Secretaria de Estado de Cultura (SEC/MG), por meio do Arquivo Público Mineiro (APM), órgão coordenador do Projeto e da Superintendência de Bibliotecas Públicas (SUB). Conta ainda com a participação do Arquivo Público de Uberaba. A partir das diretrizes de regionalização da política cultural do Estado, o resultado principal do projeto será a implantação de um polo de digitalização de acervos documentais históricos no Arquivo Público de Uberaba, que deverá atuar como órgão catalizador e executor de projetos de digitalização nas regiões acima mencionadas. O projeto se fundamenta nas metodologias de organização, preservação e digitalização de acervos documentais preconizadas pelo <strong>Programa Conservação Preventiva em Bibliotecas e Arquivos</strong>, nas recomendações do Conselho Nacional de Arquivos (CONARQ) e nas regras do Código de Catalogação Anglo-americano (CCAA2).</p><p><strong><br /></strong></p><p><strong>Abstract</strong></p><p>“The Printing Press Memorial of Uberaba: the creation of the newspapers´ digital library of Triângulo Mineiro and Alto Paranaíba (Minas Gerais, Brazil)” is probably, the biggest project in the field of historical collections preservation ever funded by the Fundação de Amparo à Pesquisa do Estado de Minas Gerais – FAPEMIG. The project was conceived and has been carried out by the Secretaria de Estado de Ciência, Tecnologia e Ensino Superior, along with the Secretaria de Estado de Cultura, through the participation of the Arquivo Público Mineiro, the coordinating body, and the Superintendência de Bibliotecas Públicas. The<em> </em>Arquivo Público de Uberaba is the third body involved with the implementation of the project. In accordance with the regionalization policies of the State, the main achievement of the project shall be the creation of a digitalization center of historical collections in the Arquivo Público de Uberaba. This institution shall act as a regional agency for the development of digitalization projects in the regions of Triângulo Mineiro and Alto Paranaíba. The project is based on the methodologies of organization, preservation and digitalization of historical collections, recommended by the Programa de Conservação Preventiva em Bibliotecas e Arquivos, the guidelines of the Conselho Nacional de Arquivos<em> </em>(CONARQ) and the Anglo American Cataloguing Rules (AACR2).</p><p><strong>Keywords</strong>: Digitalization of Historical collections; Preservation of Historical Collections; Digital Libraries.</p>


2020 ◽  
Vol 56 (2) ◽  
pp. 179-191
Author(s):  
C. Kamil ◽  
H. A. Dal ◽  
O. Özdarcan ◽  
E. Yoldaş

We present new findings about KIC 8043961. We find the effective temperatures of the components as 6900 ± 200 K for the primary, and 6598 ± 200 K for the secondary, while the logarithm of the surface gravities are found to be 4.06 cm s-2 and 3.77 cm s-2, respectively. Combination of the light curve with the spectroscopic orbit model results leads to a mass ratio of 1.09 ± 0.07 with an orbital inclination of 73.71 ± 0.14 and a semi-major axis of 8.05 ± 0.22 R⨀ . Masses of the primary and secondary components are calculated as 1.379 ± 0.109 M⨀ and 1.513 ± 0.181 M⨀, while the radii are found to be 1.806 ± 0.084 R⨀ and 2.611 ± 0.059 R⨀. In addition, we obtain a considerable light contribution (≈0.54%) of a third body. We compute a possible mass for the third body as 0.778 ± 0.002 M⨀. We find that the primary component exhibits γ Dor type pulsations with 137 frequencies.


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