Experimental Studies on the Friction Parameters of Polyurethane Elastomers Used for Cup-Type Sealing

2020 ◽  
Vol 49 (12) ◽  
pp. 1084-1088
Author(s):  
S. N. Yakovlev
Lubricants ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 110 ◽  
Author(s):  
Michael Müller ◽  
Lukas Stahl ◽  
Georg-Peter Ostermeyer

Starved lubrication is an important strategy for minimizing the amount of lubricant needed, and also inevitably occurs during idling and fail-safe lubrication. In this regime, however, the flow of the lubricant and the related friction coefficients are yet to be fully understood. This research aims to make fundamental contributions to the understanding of contact mechanics of partially lubricated contacts. Recent experiments with a pin-on-disk tribometer examined the microscopic behavior of partially filled gaps. Using a new experimental setup on a macroscale, new insights into partially filled gaps with rough surfaces were gained. This work presents the systematic analyses of the lubricant flow, friction coefficients, and other variables over a wide range of friction parameters. Distinct friction behaviors were observed, and similar effects occur on both the micro and macroscale. The experimental results show that a typical Stribeck characteristic is visible regarding not only the relative velocity, but also regarding the lubricant filling level in the gap. The fluid exhibits a variety of flow patterns for various velocities and viscosities. The patterns relate to different friction regimes, such as dry friction and mixed lubrication. It is concluded that the filling level is a valid parameter for regulating the transition from dry friction to hydrodynamic lubrication. These findings are quantified regarding the filling level and it is shown that for the identification of the friction regimes the filling level is an independent parameter in addition to the established parameters like speed, viscosity and pressure.


2020 ◽  
Vol 17 (5) ◽  
pp. 78-95
Author(s):  
S. V. Bespalko ◽  
E. G. Kurzina ◽  
A. M. Kurzina ◽  
I. Zh. Zhaisan

The task of achieving the increase in the weight and velocity of trains being core objective for most railways is inherently associated with solving problems of improving the dynamic qualities of wagons and locomotives during their interaction with the upper structure of the railway track. The strength and stability of rolling stock against derailment in various climatic zones should be ensured together with minimizing operating costs.Analysis of the reliability and performance of the wagon–track system can be conducted based on multivariate dynamic calculations of mathematical models and through experimental studies of dynamic vibrations. Currently, the issues of the influence of changes in the elastic-hysteresis properties of various impact absorber materials under the action of temperature factors on the elements of a multi-mass vibratory system remain insufficiently studied. The purpose of the research described in the article was to analyze the dynamic processes taking place in a multi-mass wagon–track vibratory system under the influence of changes in stiffness and internal friction coefficients of a damping rail component depending on a type of structural material and ambient temperature.The research resulted in elaborating model of multi-mass vibratory wagon–track system. Multivariate model calculations were carried out regarding various stiffness and internal friction parameters of damping elements situated under the rail; the parameters being selected from experimentally constructed dynamic hysteresis. The work presents results of calculations of the reaction forces and deviations in the elements of the vibratory system depending on temperature, type of material, thickness and design of damping elements.


Author(s):  
Kent McDonald ◽  
David Mastronarde ◽  
Rubai Ding ◽  
Eileen O'Toole ◽  
J. Richard McIntosh

Mammalian spindles are generally large and may contain over a thousand microtubules (MTs). For this reason they are difficult to reconstruct in three dimensions and many researchers have chosen to study the smaller and simpler spindles of lower eukaryotes. Nevertheless, the mammalian spindle is used for many experimental studies and it would be useful to know its detailed structure.We have been using serial cross sections and computer reconstruction methods to analyze MT distributions in mitotic spindles of PtK cells, a mammalian tissue culture line. Images from EM negatives are digtized on a light box by a Dage MTI video camera containing a black and white Saticon tube. The signal is digitized by a Parallax 1280 graphics device in a MicroVax III computer. Microtubules are digitized at a magnification such that each is 10-12 pixels in diameter.


Author(s):  
Ina Grau ◽  
Jörg Doll

Abstract. Employing one correlational and two experimental studies, this paper examines the influence of attachment styles (secure, anxious, avoidant) on a person’s experience of equity in intimate relationships. While one experimental study employed a priming technique to stimulate the different attachment styles, the other involved vignettes describing fictitious characters with typical attachment styles. As the specific hypotheses about the single equity components have been developed on the basis of the attachment theory, the equity ratio itself and the four equity components (own outcome, own input, partner’s outcome, partner’s input) are analyzed as dependent variables. While partners with a secure attachment style tend to describe their relationship as equitable (i.e., they give and take extensively), partners who feel anxious about their relationship generally see themselves as being in an inequitable, disadvantaged position (i.e., they receive little from their partner). The hypothesis that avoidant partners would feel advantaged as they were less committed was only supported by the correlational study. Against expectations, the results of both experiments indicate that avoidant partners generally see themselves (or see avoidant vignettes) as being treated equitably, but that there is less emotional exchange than is the case with secure partners. Avoidant partners give and take less than secure ones.


Author(s):  
Anne Andronikof

Based on an analysis of John Exner’s peer-reviewed published work from 1959 to 2007, plus a brief comment for an editorial in Rorschachiana, the author draws a comprehensive picture of the scientific work of this outstanding personality. The article is divided into three sections: (1) the experimental studies on the Rorschach, (2) the clinical studies using the Rorschach, and (3) Exner’s “testament,” which we draw from the last paper he saw published before his death (Exner, 2001/2002). The experimental studies were aimed at better understanding the nature of the test, in particular the respective roles of perception and projection in the response process. These fundamental studies led to a deeper understanding of the complex mechanisms involved in the Rorschach responses and introduced some hypotheses about the intentions of the author of the test. The latter were subsequently confirmed by the preparatory sketches and documents of Hermann Rorschach, which today can be seen at the H. Rorschach Archives and Museum in Bern (Switzerland). Exner’s research has evidenced the notion that the Rorschach is a perceptive-cognitive-projective test.


2013 ◽  
Vol 44 (2) ◽  
pp. 117-128 ◽  
Author(s):  
Mauro Bertolotti ◽  
Patrizia Catellani ◽  
Karen M. Douglas ◽  
Robbie M. Sutton

In two experimental studies (conducted in Britain and Italy), participants read about a politician answering to leadership- versus morality-related allegations using either downward counterfactuals (“things could have been worse, if ...”) or upward counterfactuals (“things could have been better, if ...”). Downward messages increased the perception of the politician’s leadership, while both downward and upward messages increased morality perception. Political sophistication moderated the effect of message direction, with downward messages increasing perceived morality in low sophisticates and upward messages increasing perceived morality in high sophisticates. In the latter group, the acknowledgment of an intent to take responsibility mediated morality judgment. Results were consistent across different countries, highlighting previously unexplored effects of communication on the perception of the “Big Two” dimensions.


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