Coupling fractal model for fretting wear on rough contact surfaces

2020 ◽  
pp. 1-32
Author(s):  
Yi Wang ◽  
Gang Liang ◽  
Shuo LIU ◽  
Yi Cui
Keyword(s):  
Contact Surface ◽  
Fractal Theory ◽  
Three Dimensional ◽  
Parameter Analysis ◽  
Fretting Wear ◽  
Wear Depth ◽  
Contact Parameter ◽  
Wear Process ◽  
Actual Surface ◽  
Fractal Parameters

Abstract In this paper, a fretting damage model based on fractal theory is proposed. The Weierstrass-Mandelbrot function of fractal theory is used to represent the rough contact surface, and a corresponding contact parameter analysis method is also established. Based on neural network algorithm, the values of fractal parameters are fitted, and the fitting accuracy has been greatly improved compared with traditional methods. According to the fractal parameters of the actual surface, the fretting wear process of the rough contact surface is analyzed based on theory of adhesive and three body abrasive wear. A generic program for the analysis of three-dimensional fretting wear problems is also proposed. Compared with material tests, the prediction error of fretting wear simulation model is 13.4% for wear depth and 16.7% and 3.9% for width and length of wear scar in stable wear stage. The prediction results show that the model can be applied to the prediction of the actual three-dimensional fretting wear model.

A Numerical Simulation of Fretting Wear considering the Dynamic Evolution of Debris for the Coated Contact Surface

2021 ◽  
pp. 1-49
Author(s):  
Li Xiao ◽  
Yingqiang Xu ◽  
Zhiyong Chen
Keyword(s):  
Fretting Wear ◽  
Contact Pair ◽  
Dynamic Evolution ◽  
Wear Depth ◽  
Wear Coefficient ◽  
Wear Model ◽  
Wear Process ◽  
Dlc Coating ◽  
Wear Life ◽  
Wear Calculation

Abstract In this paper, a multi-layer body model in which material properties and wear coefficient change with node coordinates is proposed, so that the wear profile is not restricted by the singularity of the interface of the coated contact pairs. The conversion rate of the adhered particles was obtained to describe the growth and expansion of the debris at the fretting interface based on experiments, and the wear model of coated contact pair considering the dynamic evolution of the debris layer was established. By comparing the previous experimental and computational results, the wear calculation method proposed in this paper is more reasonable to predict the wear profile of the coated contact pair. In addition, the influence of the debris layer on the wear depth, friction width, and contact pressure in the fretting process is analyzed, indicating that the existence of the debris layer can delay the wear process. Finally, the fretting wear life of the SCMV steel contact pair deposited with the W-DLC coating is estimated.

Fretting Wear of CMSX4 at Blade Tip Interface With and Without Coating

2009 ◽  
Author(s):  
M. Lavella ◽  
D. Botto ◽  
M. M. Gola
Keyword(s):  
Flat Surface ◽  
Contact Stiffness ◽  
Three Dimensional ◽  
Large Change ◽  
Fretting Wear ◽  
Wear Behaviour ◽  
Wear Process ◽  
Blade Tip ◽  
Coated Surfaces ◽  
Contact Parameters

Fretting wear is a complex phenomenon that occurs at component interfaces that are subjected to low amplitude oscillation under high contact pressure. In turbomachinery fretting occurs also at the blade tip interfaces where shrouds, that have the aim to reduce the blade resonant vibration amplitude, are machined. To diminish the fretting damage coatings are applied to the blade tips. The aim of this study is to compare the fretting wear behaviour of single crystal CMSX-4 superalloy interfaces with and without plasma sprayed T-800 coating. Experiments have been conducted with hemispherical surface in contact with a flat surface of the same materials at temperature of 800 °C. The hysteresis cycles have been measured through the experiment. The comparison of the hysteresis cycles shown that the tangential contact stiffness of the coated surfaces is greater then that of the surfaces without coating. At the end of wear process, the mating surfaces have been characterized by three-dimensional optical interferometry and SEM analysis. After 10×106 wear cycles, the uncoated surfaces show a large change in the contact parameters and fretting cracks on the flat surface. On the other hand, the coated surfaces do not shows a measurable change in the contact parameters while the coating damage on the flat surface leads to predict an incipient catastrophic wear.

scholarly journals Effects of Loading Conditions and Types of Motion on PWR Fuel Rod Cladding Wear

2002 ◽  
Author(s):  
T. P. Joulin ◽  
F. M. Gue´rout ◽  
A. Lina ◽  
D. Moinereau
Keyword(s):  
Three Dimensional ◽  
Fretting Wear ◽  
Primary Circuit ◽  
Loading Conditions ◽  
Pressurized Water Reactor ◽  
Pressurized Water ◽  
Wear Process ◽  
Fuel Rod ◽  
Support Cell ◽  
Wear Tests

The objective of this study was to investigate the effects of types of motion and loading conditions on the wear of Pressurized Water Reactor (PWR) fuel rod cladding made of Zircaloy-4 in contact with a grid support cell. Fretting-wear tests, for various combinations of motion and preload, were conducted at 310°C and 11.7 MPa using primary circuit water chemistry. Wear coefficients, derived from three-dimensional profilometry, were used to assess the severity of the wear process. The types of motion and the loading conditions were found to have a significant interdependent effect on fuel rod wear coefficients. Scanning Electron Microscope (SEM) examinations were performed on the worn fuel rod cladding specimens to identify wear mechanisms.

Effects of attapulgite on the worn surface and fretting wear resistance property of UHMWPE composites

2020 ◽  
Vol 72 (7) ◽  
pp. 821-827
Author(s):  
Zhaojie Meng ◽  
Yunxia Wang ◽  
Xiaocui Xin ◽  
Hao Liu ◽  
Yunfeng Yan ◽  
...  
Keyword(s):  
Wear Resistance ◽  
Peer Review ◽  
Filler Content ◽  
Resistance Mechanism ◽  
Three Dimensional ◽  
Fretting Wear ◽  
Wear Property ◽  
Pressing Method ◽  
Content Type ◽  
Worn Surface

Purpose The purpose of this study is to examine the fretting wear property of ultra-high molecular weight polyethylene (UHMWPE)-based composites reinforced by different content of attapulgite. Design/methodology/approach A series of composites were prepared by a hot-pressing method. Fretting tests were carried out using an SRV-IV oscillating reciprocating friction wear tester with a load of 10 N and a frequency of 100 Hz. The morphology of the fracture structure and the worn surface was observed by field-emission scanning electron microscopy, X-ray diffraction and a non-contact three dimensional surface profiler. Findings With the addition of attapulgite, the microstructure of the composites become more regular, and their heat resistance improved. Furthermore, the friction coefficient and the specific wear rate of the composites with lower filler content reduced compared with that of neat UHMWPE, and the optimum filler content is 1 per cent. Originality/value The study investigated the fretting resistance mechanism of the attapulgite in the UHMWPE matrix. The results could help to provide some experimental evidence for the broader application of silicates on the fretting wear resistance of polymers. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-10-2019-0420/

scholarly journals Dynamical behavior of coal shearer under the influence of multiple factors in slant-cutting conditions

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Xinwei Yang ◽  
Xianfeng Zou ◽  
Shuai Zhang ◽  
Hongyue Chen ◽  
Yajing Wei ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Fractal Theory ◽  
Dynamical Behavior ◽  
Three Dimensional ◽  
Cutting Conditions ◽  
Vibration Displacement ◽  
Flexible Beams ◽  
Swing Angle ◽  
Wear And Tear ◽  
Working Parameters

AbstractAiming at the problem of severe vibration and abnormal wear and tear of various components in coal shearer under slant-cutting conditions, a non-linear dynamics model with 13 degrees of freedom for a coal shearer under slant-cutting conditions is developed using vibration mechanics and multi-body dynamics theory, and the characteristics of the slide shoes-middle groove contact, the ranging arm-haulage unit connection with gaps and the guidance sliding boots-pin rail multi-surface contact with gaps are described based on three-dimensional fractal theory and Hertz contact theory. Based on Huco's law, the ranging arm and the hydraulic rod are assumed to be flexible beams, the rigidity characteristics of the ranging arm itself, the connection characteristics of the haulage unit and the fuselage are described, a drum correction load with a traction speed correction factor is proposed as the external excitation of the system, and the model is solved and analyzed. The research results show that the change of traction speed has a greater influence on the vibration swing angle and displacement of the front drum, front ranging arm and front walking unit, and the vibration swing angle and displacement of the three increase with the increase of traction speed, while the change of coalface hardness coefficient has less influence on the vibration displacement of the key components of the coal shearer. Under the working parameters of v = 3 m/min and f = 3, the swing angle and displacement of the front ranging arm and front drum fluctuate in the ranges of − 0.4–0.1 rad and – 15–15 mm respectively; the vibration acceleration is – 300–300 rad/s2 and – 200–200 mm/s2 respectively, the main vibration frequencies are 16.63 Hz and 12.14 Hz respectively, and finally the results are verified by experimental methods.

scholarly journals Physiological State and Learning Ability of Students in Normal and Virtual Reality Conditions: Complexity-Based Analysis (Preprint)

2020 ◽  
Author(s):  
Mohammad H Babini ◽  
Vladimir V Kulish ◽  
Hamidreza Namazi
Keyword(s):  
Virtual Reality ◽  
Fractal Theory ◽  
Physiological State ◽  
Three Dimensional ◽  
Physiological Signals ◽  
Learning Ability ◽  
Two Dimensional ◽  
Reality Condition ◽  
Computer Mediated ◽  
Dimensional Condition

BACKGROUND Education and learning are the most important goals of all universities. For this purpose, lecturers use various tools to grab the attention of students and improve their learning ability. Virtual reality refers to the subjective sensory experience of being immersed in a computer-mediated world, and has recently been implemented in learning environments. OBJECTIVE The aim of this study was to analyze the effect of a virtual reality condition on students’ learning ability and physiological state. METHODS Students were shown 6 sets of videos (3 videos in a two-dimensional condition and 3 videos in a three-dimensional condition), and their learning ability was analyzed based on a subsequent questionnaire. In addition, we analyzed the reaction of the brain and facial muscles of the students during both the two-dimensional and three-dimensional viewing conditions and used fractal theory to investigate their attention to the videos. RESULTS The learning ability of students was increased in the three-dimensional condition compared to that in the two-dimensional condition. In addition, analysis of physiological signals showed that students paid more attention to the three-dimensional videos. CONCLUSIONS A virtual reality condition has a greater effect on enhancing the learning ability of students. The analytical approach of this study can be further extended to evaluate other physiological signals of subjects in a virtual reality condition.

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