COLD WELDING DUE TO IMPACT AND FRETTING UNDER VACUUM.: CONSIDERING SCALING FOR APPLICATIONS IN SPACE MECHANISMS

Author(s):  
Andreas Merstallinger ◽  
Muriel Sales
Lubricants ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 72
Author(s):  
Andreas Merstallinger ◽  
Roland Holzbauer ◽  
Nathan Bamsey

Cold welding refers to an effect related to space (vacuum). The heavy vibrations during a launch subject interfaces (hold down points) to oscillating motions which may lead to formation of a kind of “friction weld”. If so, these mechanisms may get stuck, and deployment will be hindered. This may endanger the functionality of the mission (instruments) or even the whole spacecraft (if solar panels do not open). Several studies have been done to characterize material combinations (including coatings) for their ability to cold welding in space. Meanwhile, also during launch grease free contacts are demanded. If grease hat to be omitted, the risk of cold welding under fretting was found to increase (when testing in high vacuum). To rate this risk under launch conditions, the test method was recently extended for testing under launch conditions. The new tests procedure consists of fretting applied in the sequence in air, low vacuum and high vacuum. The paper shall present first results gained with this new method of testing in launch conditions and compare them to previous studies done in vacuum. Following the need of space industry on mechanisms for launch and in-orbit life, a first set of combinations of materials and coatings were selected for this new test sequence where fretting is now applied in a sequence of air, low vacuum and high vacuum. Under this sequence, the measured levels of adhesion and it’s evolvement was found to differ strongly from tests done formerly. The paper outlines these first results and compares them to existing data.


Author(s):  
Larysa Gromozdova ◽  
Inna Stenicheva

Purpose of the article: to determine the essence of different elements ofsocio-economic space of the region. Construction of the structure and isolationof individual elements of socio-economic space as a multi-vector formation.This article highlights the essence and different approaches to defining theconcepts, structure and mechanisms of formation of economic and social spacesof the region, innovation space as a basic element of socio-economic space.Research Methods: The methodological basis of the research is the fundamentalprinciples of economic theory, regional economy, scientific views and approachesof foreign and domestic scientists. To achieve the purpose of the study, themethods used at the empirical and theoretical levels were used: axiomatic,abstract, system-structural analysis, analogies and comparisons, graphoanalytic,by which the characterization of the nature of the concepts of space, socioeconomic space, as well as innovation space region. Their general properties,structure and functions are described.The criteria of optimality and balancesof interests in the formation of different types of space in the region areconsidered. The classification of the regional space is proposed, and the networkconnections of the innovation space according to components and elements arerevealed, which allows to study deeply the social, economic and other problemsof development of the region.Scientific novelty: the classification of regionalspace by separate constituent elements is proposed. The concept of “innovationspace” was introduced into scientific circulation, the scheme of networkconnections of the innovation space with other elements of the regional socioeconomic space was developed. Conclusions and Prospects for Further Research:In today’s context, it is possible to significantly improve the economic stateof development of Ukrainian regions by using a scientifically sound andcomprehensive approach to defining and studying the concepts of socioeconomic and innovative space.In the further study it is necessary to considerin detail the mechanism of organizational activity of innovation space in theregion. It is very important to pay attention to information support for theformation of the innovation space, the creation of a regional legal field ofinnovation space, mechanisms for coordinating regional innovation activitieswithin the innovation space, as well as the influence of internal and externalfactors on the formation and development of the innovation space.


2011 ◽  
Vol 295-297 ◽  
pp. 1251-1258 ◽  
Author(s):  
Jian Guo Yang ◽  
Lu Yong Huang ◽  
Hai Bo Pan ◽  
Xue Song Liu ◽  
Hong Yuan Fang

As a kind of the high strength low alloy steel (HSLA), 30CrMoSi has been used widely in some industrial fields. However, just like some HSLA, this steel also faces some problems when it is welded, especially such problem as cold cracking in the welded joints. In this paper, the cold welding cracks and microstructure of the joints of 30CrMoSi steel were studied by scanning electron microscopy (SEM) and optical microscopy (OM), and a method called welding with trailing impacting and rolling (WTIR) was utilized to solve the problem mentioned above by decreasing the residual welding stress which is one main factor to lead to cold welding crack in the joint of HSLA. The crack-free joints of 30CrMoSi steel were obtained by using proper parameters.


2004 ◽  
Vol 20 (4) ◽  
pp. 303-315 ◽  
Author(s):  
W. R. Jones ◽  
M. J. Jansen ◽  
L. J. Gschwender ◽  
C. E. Snyder ◽  
S. K. Sharma ◽  
...  

Author(s):  
Yuhang Zhang ◽  
Jiejie Li ◽  
Hongjian Zhou ◽  
Yiqun Hu ◽  
Suhang Ding ◽  
...  

Author(s):  
Chao Zhang ◽  
Shaoping Wang

Solid lubricated bearings are commonly used in space mechanisms and other appliances, and their reliability analysis has drawn more and more attention. This paper focuses on the performance degradation analysis of solid lubricated bearings. Based on the vibration and friction torque signal of solid lubricated bearings, Laplace wavelet filter is adopted to process vibration signal and feature vector is constructed by calculating time-domain parameters of filtered vibration signal and original friction torque signal. Self-organizing map is then adopted to analyze the performance degradation based on extracted feature vectors. Experimental results show that this method can describe performance degradation process effectively.


2014 ◽  
Vol 214 (10) ◽  
pp. 2040-2048 ◽  
Author(s):  
Peter Groche ◽  
Simon Wohletz ◽  
Andreas Erbe ◽  
Abdulrahman Altin

2017 ◽  
Vol 30 (2) ◽  
pp. 332-343 ◽  
Author(s):  
Yong LI ◽  
Shengle CHEN ◽  
Jinlong HUANG ◽  
Yuying YAN ◽  
Zhixin ZENG

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