A study of the compression stability of a coupler under initial asymmetric conditions

2021 ◽  
pp. 095440972110388
Author(s):  
Ruiming Zou ◽  
Shihui Luo ◽  
Weihua Ma
Keyword(s):  
Friction Coefficient ◽  
Stability Margin ◽  
Static Friction ◽  
The Self ◽  
Lateral Deviation ◽  
Running Safety ◽  
Static Friction Coefficient ◽  
The Stability ◽  
Asymmetrical Condition ◽  
Assembly Deviation

In practice, due to the influence of assembly deviation, clearance, vibration and other objective factors, the coupler will inevitably work under asymmetrical conditions in the buffing state. However, the existing theoretical studies on the compression stability of couplers did not pay enough attention to this condition, and most of the studies are based on the premise of ideal symmetry conditions. In this paper, the initial lateral deviation between the ends of a coupling coupler is taken as a typical asymmetrical condition, and the influence of the initial asymmetrical condition on the compression stability of the coupler is analysed by theoretical analysis and dynamic simulation. The results show that with the increase of the initial lateral deviation, the rotation angle of the coupler will also increase when it reaches the self-stabilizing equilibrium point. Therefore, the initial asymmetry will reduce the stability margin of the coupler, and then weaken the self-stabilizing ability and compression stability of the coupler. Improving the symmetry of the coupler is also one of the effective methods to guarantee the compression stability of the coupler and the running safety of the locomotive. When the static friction coefficient of the coupler tail can reach 0.3, the initial lateral deviation of the coupler should be limited to less than 7 mm, and the smaller the static friction coefficient, the higher the requirements for the initial lateral deviation.

Measurements of the Static Friction Coefficient Between Tin Surfaces and Comparison to a Theoretical Model

2011 ◽  
Vol 133 (3) ◽  
Author(s):  
Rebecca D. Ibrahim Dickey ◽  
Robert L. Jackson ◽  
George T. Flowers
Keyword(s):  
Theoretical Model ◽  
Friction Coefficient ◽  
Human Error ◽  
Surface Profile ◽  
Static Friction ◽  
Quantitative Agreement ◽  
High Plasticity ◽  
Static Friction Coefficient ◽  
Experimental Apparatus ◽  
Rough Surface Contact

A new experimental apparatus is used to measure the static friction between tin surfaces under various loads. After the data is collected it is then compared to an existing theoretical model. The experiment uses the classical physics technique of increasing the incline of a plane and block until the block slides. The angle at the initiation of sliding is used to find the static friction coefficient. The experiment utilizes an automated apparatus to minimize human error. The finite element based statistical rough surface contact model for static friction under full stick by Li, Etsion, and Talke (2010, “Contact Area and Static Friction of Rough Surfaces with High Plasticity Index,” ASME Journal of Tribology, 132(3), p. 031401) is used to make predictions of the friction coefficient using surface profile data from the experiment. Comparison of the computational and experimental methods shows similar qualitative trends, and even some quantitative agreement. After adjusting the results for the possible effect of the native tin oxide film, the theoretical and experimental results can be brought into reasonable qualitative and quantitative agreement.

scholarly journals Brittle Fracture Theory Describes the Onset of Frictional Motion

2019 ◽  
Vol 10 (1) ◽  
pp. 253-273 ◽  
Author(s):  
Ilya Svetlizky ◽  
Elsa Bayart ◽  
Jay Fineberg
Keyword(s):  
Friction Coefficient ◽  
Brittle Fracture ◽  
Static Friction ◽  
Quantitative Agreement ◽  
Interface Fracture ◽  
Earthquake Dynamics ◽  
Rupture Dynamics ◽  
Static Friction Coefficient ◽  
Fracture Theory ◽  
Macroscopic Motion

Contacting bodies subjected to sufficiently large applied shear will undergo frictional sliding. The onset of this motion is mediated by dynamically propagating fronts, akin to earthquakes, that rupture the discrete contacts that form the interface separating the bodies. Macroscopic motion commences only after these ruptures have traversed the entire interface. Comparison of measured rupture dynamics with the detailed predictions of fracture mechanics reveals that the propagation dynamics, dissipative properties, radiation, and arrest of these “laboratory earthquakes” are in excellent quantitative agreement with the predictions of the theory of brittle fracture. Thus, interface fracture replaces the idea of a characteristic static friction coefficient as a description of the onset of friction. This fracture-based description of friction additionally provides a fundamental description of earthquake dynamics and arrest.

Numerical Investigation of the Influence of Friction Coefficient on Brake Groan

2010 ◽  
Vol 44-47 ◽  
pp. 1923-1927 ◽  
Author(s):  
Xian Jie Meng
Keyword(s):  
Nonlinear Dynamics ◽  
Friction Coefficient ◽  
Degrees Of Freedom ◽  
Equilibrium Points ◽  
Static Friction ◽  
Kinetic Friction ◽  
Dynamics Model ◽  
Excited Vibration ◽  
Nonlinear Dynamics Model ◽  
The Stability

A two degrees of freedom nonlinear dynamics model of self-excited vibration induced by dry-friction of brake disk and pads is built firstly, the stability of vibration system at the equilibrium points is analyzed using the nonlinear dynamics theory. Finally the numerical method is taken to study the impacts of friction coefficient on brake groan. The calculation result shows that with the increase of kinetic friction coefficient /or the decrease of difference value between static friction coefficient and kinetic friction coefficient can prevent or restrain self-excited vibration from happening.

scholarly journals A Novel Process for Manufacturing High-Friction Rings with a Closely Defined Coefficient of Static Friction (Relative Standard Deviation 3.5%) for Application in Ship Engine Components

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 448
Author(s):  
Wojciech S. Gora ◽  
Jesper V. Carstensen ◽  
Krystian L. Wlodarczyk ◽  
Mads B. Laursen ◽  
Erica B. Hansen ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Friction Coefficient ◽  
Relative Standard Deviation ◽  
Static Friction ◽  
Laser Surface ◽  
Laser Surface Texturing ◽  
Textured Surface ◽  
Fibre Lasers ◽  
Static Friction Coefficient ◽  
Relative Standard

In recent years, there has been an increased uptake for surface functionalization through the means of laser surface processing. The constant evolution of low-cost, easily automatable, and highly repeatable nanosecond fibre lasers has significantly aided this. In this paper, we present a laser surface-texturing technique to manufacture a surface with a tailored high static friction coefficient for application within driveshafts of large marine engines. The requirement in this application is not only a high friction coefficient, but a friction coefficient kept within a narrow range. This is obtained by using nanosecond-pulsed fibre lasers to generate a hexagonal pattern of craters on the surface. To provide a suitable friction coefficient, after laser processing the surface was hardened using a chromium-based hardening process, so that the textured surface would embed into its counterpart when the normal force was applied in the engine application. Using the combination of the laser texturing and surface hardening, it is possible to tailor the surface properties to achieve a static friction coefficient of ≥0.7 with ~3–4% relative standard deviation. The laser-textured and hardened parts were installed in driveshafts for ship testing. After successfully performing in 1500 h of operation, it is planned to adopt the solution into production.

scholarly journals Active Sensing of Static Friction Coefficient ^|^mu; for Controlling Grasping Force

1994 ◽  
Vol 30 (10) ◽  
pp. 1188-1194 ◽  
Author(s):  
Youji YAMADA ◽  
Kenji SANDA ◽  
Kazuhide FUJITA ◽  
Nuio TSUCHIDA ◽  
Kouji IMAI
Keyword(s):  
Friction Coefficient ◽  
Static Friction ◽  
Active Sensing ◽  
Static Friction Coefficient ◽  
Grasping Force

Research for a Projectile Positioning Structure for Stacked Projectile Weapons

2011 ◽  
Vol 78 (5) ◽  
Author(s):  
Qiao Luo ◽  
Xiaobing Zhang
Keyword(s):  
Friction Coefficient ◽  
Structural Parameters ◽  
Static Friction ◽  
Element Model ◽  
Ballistic Performance ◽  
Static Friction Coefficient ◽  
Key Technologies ◽  
Contact Surfaces ◽  
Proper Material ◽  
Multibody Contact

One of the key technologies of stacked projectile weapons is projectile positioning. However, the present projectile positioning structures have their respective advantages and shortcomings. A new structure based on the self-locking principle is put forward in this paper and verified as feasible by static analysis if the proper material and structural parameters are chosen. In order to check the strength and verify the feasibility of the structure under launch conditions, the multibody contact finite element model of the structure is established, coupled with dynamic load in the interior ballistic cycle. According to simulations and analysis, the projectile positioning structure is feasible and the strength of the projectile can meet the strength requirement for launch conditions. For different maximum static friction coefficients, simulations show that an increase in the maximum static friction coefficient between the contact surfaces of the positioning ring and barrel improves the positioning performance, but an increase in the maximum static friction coefficient between the contact surfaces of the positioning ring and projectile worsens. On the basis of great computation, it is found that an increase in the upper thickness and height of the positioning ring improves the positioning performance, but an increase in the lower thickness worsens the positioning performance. Further, a lower thickness affects the positioning performance more greatly. As a result, the positioning ring will be thin and light to improve the positioning performance. Compared with other positioning structures, the new structure has little influence on the ballistic performance and is a good application prospect.

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