stick slip motion
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2022 ◽  
Vol 164 ◽  
pp. 108226
Author(s):  
Saeed Gheisari Hasnijeh ◽  
Hossein Karimpour ◽  
Mehrdad Poursina

2021 ◽  
Vol 9 ◽  
Author(s):  
C. J. O. Reichhardt ◽  
C. Reichhardt

We numerically examine the dynamics of individually dragged skyrmions interacting simultaneously with an array of other skyrmions and quenched disorder. For drives just above depinning, we observe a broadband noise signal with a 1/f characteristic, while at higher drives, narrowband or white noise appears. Even in the absence of quenched disorder, the threshold force that must be applied to translate the driven skyrmion is finite due to elastic interactions with other skyrmions. The depinning threshold increases as the strength of the quenched disorder is raised. Above the depinning force, the skyrmion moves faster in the presence of quenched disorder than in a disorder-free system since the pinning sites prevent other skyrmions from being dragged along with the driven skyrmion. For strong pinning, we find a stick-slip motion of the driven skyrmion which produces a telegraph noise signature. The depinning threshold increases monotonically with skyrmion density in the absence of quenched disorder, but when pinning is present, the depinning threshold changes nonmonotonically with skyrmion density, and there are reentrant pinned phases due to a competition between pinning induced by the quenched disorder and that produced by the elastic interactions of the skyrmion lattice.


2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Qin Lian ◽  
Chunxu Yang ◽  
Jifei Cao

The transition between static and kinetic frictions of steel/shale pairs has been studied. It was found that the coefficient of friction decreased exponentially from static to dynamic friction coefficient with increasing sliding displacement. The difference between static and dynamic friction coefficients and the critical distance Dc under the dry friction condition is much larger than that under the lubricated condition. The transition from static to dynamic friction coefficient is greatly affected by the normal load, quiescent time, and sliding velocity, especially the lubricating condition. Maintaining continuous lubrication of the contact area by the lubricant is crucial to reduce or eliminate the stick-slip motion. The results provide an insight into the transition from static to dynamic friction of steel/shale pairs.


2021 ◽  
Vol 38 (1−2) ◽  
Author(s):  
Tania Garcia Ramos ◽  
Andreas Zeinert ◽  
Stephen Muhl ◽  
Michaël Lejeune

The tribological, electrochemical and tribo-electrochemical behavior of bare AISI D2 was studied. The tribological aspects were tested by pin on disc with an aluminum oxide ball as counter body, the electrochemical tests were performed in an aqueous solution of citric acid and the tribo-electrochemical evaluation was through a combination of both tests. AISI D2 steel presented abrasive wear in dry and wet conditions, such type of wear occurred due to stick-slip motion, moreover, in wet conditions the alloy corroded at corrosion current values around 10-6 A/cm2.  The damage produced over the wear track was larger under wet conditions than for the dry conditions.


2021 ◽  
Author(s):  
Luca Marino ◽  
Alice Cicirello

Abstract This paper investigates the steady-state response of a multi-degree-of-freedom (MDOF) system with a Coulomb contact to harmonic excitation. Although discrete MDOF models are commonly used at early design stages to analyse the dynamic performances of engineering structures, the current understanding of the friction damping effects on MDOF behaviour is still limited due to the absence of analytical solutions. In this contribution, closed-form expressions of the continuous time response, the displacement transmissibility and the phase angle of each mass of the system are derived and validated numerically for 2DOF and 5DOF systems. Moreover, the features of the analytical response are investigated, obtaining the following results: (i) the determination of the minimum amounts of friction for which the resonant peaks become finite and (ii) for which stick-slip motion can be observed at high frequencies; (iii) an equation for the evaluation of invariant points for the displacement transmissibilities; (iv) a better understanding of phenomena such as the inversions of the transmissibility curves and the onset of additional resonant peaks due to the permanent sticking of the mass in contact. All these results show that MDOF systems exhibit significantly different dynamic behaviours depending on whether the friction contact and the harmonic excitation are applied to the same or different masses.


2021 ◽  
pp. 107754632110096
Author(s):  
Mohammad Mayyas

This study presents model and analysis of a robust one-dimensional stick–slip transportation of an object, on dry contact with an oscillating platform suspended by nonlinear leaf spring. The oscillating platform is designed and modeled such that the elastic spring constant is direction dependent. A recursive analytical solution algorithm is proposed to solve nonlinear system dynamics. The system and the input force parameters are both investigated with goal to optimize the average velocity of the object. Both experimental and analytical results showed that the stick–slip motion is highly nonlinear and sensitive to the system and input force parameters. Moreover, the simulations showed that it is feasible to design a platform with robust sets of parameters (natural frequencies) and further use the input force parameters (amplitude and driving frequency) to tune for desired average velocity, under given dry friction conditions.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ping Xie

AbstractKinesin-8 molecular motor can move with superprocessivity on microtubules towards the plus end by hydrolyzing ATP molecules, depolymerizing microtubules. The available single molecule data for yeast kinesin-8 (Kip3) motor showed that its superprocessive movement is frequently interrupted by brief stick–slip motion. Here, a model is presented for the chemomechanical coupling of the kinesin-8 motor. On the basis of the model, the dynamics of Kip3 motor is studied analytically. The analytical results reproduce quantitatively the available single molecule data on velocity without including the slip and that with including the slip versus external load at saturating ATP as well as slipping velocity versus external load at saturating ADP and no ATP. Predicted results on load dependence of stepping ratio at saturating ATP and load dependence of velocity at non-saturating ATP are provided. Similarities and differences between dynamics of kinesin-8 and that of kinesin-1 are discussed.


2021 ◽  
pp. 107754632110004
Author(s):  
Lu Qian ◽  
Xingwei Zhao

Creep groan is a low-frequency vibration, which is produced by the stick–slip motion from the pad–disc contact in the brake. Friction plays a key role in generating the stick–slip motion. However, directly measuring the friction force in an actual brake system is difficult. Therefore, force estimation methods are proposed to estimate the friction force based on unknown input observers. A proportional integral observer is applied to estimate the friction force amplitude from the torsional angle of the driven shaft. An approximate H2 observer is designed to distinguish the stick region and slip region from the acceleration of the pad. Different from modeling methods, designing observers do not introduce modeling deviation and have a relatively low requirement on parameter identification. In addition, the observer methods can extract more detailed information of friction force than modeling methods. The observed friction force can be considered an index to evaluate the severity of the brake defect. The performance and effectiveness of the proposed methods are confirmed by experiments on a brake test rig.


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