Mapping local defects of extended media using localized structures

2008 ◽  
Vol 93 (11) ◽  
pp. 111104 ◽  
Author(s):  
F. Pedaci ◽  
G. Tissoni ◽  
S. Barland ◽  
M. Giudici ◽  
J. Tredicce
2019 ◽  
Vol 1 (7) ◽  
pp. 10-13
Author(s):  
D. Yu. Ershov ◽  
I. N. Lukyanenko ◽  
E. E. Aman

The article shows the need to develop diagnostic methods for monitoring the quality of lubrication systems, which makes it possible to study the dynamic processes of contacting elements of the friction systems of instrument mechanisms, taking into account roughness parameters, the presence of local surface defects of elements and the bearing capacity of a lubricant. In the present article, a modern diagnostic model has been developed to control the quality of the processes of production and operation of friction systems of instrument assemblies. With the help of the developed model, it becomes possible to establish the relationship of diagnostic and design parameters of the mechanical system, as well as the appearance of possible local defects and lubricant state, which characterize the quality of friction systems used in many mechanical assemblies of the mechanisms of devices. The research results are shown in the form of nomograms to assess the defects of the elements of friction mechanisms of the mechanisms of the devices.


2007 ◽  
Vol 146 (1) ◽  
pp. 71-86 ◽  
Author(s):  
D. Gomila ◽  
P. Colet ◽  
M. S. Miguel ◽  
G.-L. Oppo

Author(s):  
M. Marconi ◽  
P. Camelin ◽  
S. Balle ◽  
J. Javaloyes ◽  
M. Giudici

Polymers ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 1954
Author(s):  
Yang Liu ◽  
Xun Zhang ◽  
Quanxin Gao ◽  
Hongliang Huang ◽  
Yongli Liu ◽  
...  

In the present study, silver (Ag) nanoparticles and maleic anhydride-grafted polyolefin elastomer (MAH-g-POE) were used as enhancement additives to improve the performance of the polyoxymethylene (POM) homopolymer. Specifically, the POM/Ag/MAH-g-POE ternary nanocomposites with varying Ag nanoparticles and MAH-g-POE contents were prepared by a melt mixing method. The effects of the additives on the microstructure, thermal stability, crystallization behavior, mechanical properties, and dynamic mechanical thermal properties of the ternary nanocomposites were studied. It was found that the MAH-g-POE played a role in the bridging of the Ag nanoparticles and POM matrix and improved the interfacial adhesion between the Ag nanoparticles and POM matrix, owing to the good compatibility between Ag/MAH-g-POE and the POM matrix. Moreover, it was found that the combined addition of Ag nanoparticles and MAH-g-POE significantly enhanced the thermal stability, crystallization properties, and mechanical properties of the POM/Ag/MAH-g-POE ternary nanocomposites. When the Ag/MAH-g-POE content was 1 wt.%, the tensile strength reached the maximum value of 54.78 MPa. In addition, when the Ag/MAH-g-POE content increased to 15wt.%, the elongation at break reached the maximum value of 64.02%. However, when the Ag/MAH-g-POE content further increased to 20 wt.%, the elongation at break decreased again, which could be attributed to the aggregation of excessive Ag nanoparticles forming local defects in the POM/Ag/MAH-g-POE ternary nanocomposites. Furthermore, when the Ag/MAH-g-POE content was 20 wt.%, the maximum decomposition temperature of POM/Ag/MAH-g-POE ternary nanocomposites was 398.22 °C, which was 71.39 °C higher than that of pure POM. However, compared with POM, the storage modulus of POM/Ag/MAH-g-POE ternary nanocomposites decreased with the Ag/MAH-g-POE content, because the MAH-g-POE elastomer could reduce the rigidity of POM.


Author(s):  
Goery Genty ◽  
Miro Erkintalo ◽  
Bertrand Kibler ◽  
Julien Fatome ◽  
Christophe Finot ◽  
...  

This paper presents a review of recent results on homogeneous turbulence. We discuss results obtained by direct numerical simulation as well as phenomenological models for the interpretation and understanding of these flows. In particular, we show that homogeneous turbulence can be well described in terms of a weakly correlated, random background field that is generally consistent with the classical Kolmogorov theory of turbulence, and strongly correlated, highly localized structures, that are largely responsible for intermittency effects and deviations from Kolmogorov scaling. These results give a unified dynamical picture of turbulence that describes both the energetics and intermittency of homogeneous turbulence, and allows us to develop a quantitative model for the description of the statistics of turbulence at small scales.


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