带基础隔震器结构的Stick-slip运动模型

带基础隔振器结构的Ｓｔｉｃｋ－ｓｌｉｐ运动研究是一个很年轻的课题．有关文献指出：带可滑动基础的结构存在Ｓｔｉｃｋ－ｓｌｉｐ运动的可能，它将导致结构失稳以及由此引起疲劳破坏，因此该类结构的Ｓｔｉｃｋ－ｓｌｉｐ运动研究是有价值的．据此，调查了在地震作用下带滑动基础或基础隔振器结构，并建立其Ｓｔｉｃｋ－ｓｌｉｐ运动的离散动力学模型，指出了系统的复杂的非线性特性．

两自由度随机干摩擦系统的Stick-slip运动

研究具有两个摩擦面的两自由度系统,引入随机摩擦模型,考虑摩擦力的随机特性,建立了系统的随机动力学模型。通过解耦,将系统分为确定性运动和随机运动的叠加。采用事件驱动法确定系统的运动状态,是全局stick状态,还是全局slip状态,或者是一个slip状态而另一个stick状态。在确定的Stick-slip运动状态下,分别求解确定性方程的解和随机方程的均值。实例分析发现,阻尼可以改变摩擦系统的运动模式跃迁的周期特性。噪声摄动改变了Stick-slip运动的运动模式,可以通过噪声摄动控制Stick-slip运动。

柔性多体系统含摩擦碰撞stick-slip过程动力学仿真

基于高次刚柔耦合理论和Lagrange乘子法,研究了柔性多体含摩擦碰撞stick-slip过程的全局动力学的精确建模与自动切换仿真问题。基于变拓扑思想,根据分离、碰撞、黏滞接触和滑动接触等状态分别构造相应的约束条件和动力学方程。运用冲量/动量法求解碰撞初始条件;引入切向滑动摩擦力势能的概念描述切向滑动接触力;给出接触、分离、黏滞、正向/逆向滑动状态之间的切换准则,实现了系统全局动力学自动切换。通过算例的数值仿真,分析了滑移/黏滞(微滑动)、正/逆向滑动等复杂非光滑现象,验证了该模型和算法的有效性。

滚珠滑动式中间轴stick-slip问题探析

转向系统作为驾驶员直接操纵的安全系统,不仅需要考虑驾驶安全,还应将客户感知作为重要考虑因素,为驾驶员提供稳定,平顺的驾驶感受。文章从理论分析入手,阐述了滚珠滑动式中间stick slip的产生原理,建立受力模型,并针对其结构和受力情况提出了两条优化方案,抑制stick slip问题的产生。

基于Stick-slip振动试验的Stribeck摩擦模型参数研究

开展了销-盘接触形式的Stick-slip(粘-滑)振动试验,分析试验结果的Stick-slip振动特性,辨识不同工况下Stick-slip振动中的摩擦参数,以及分析法向力和摩擦盘的转速对Stribeck摩擦模型中参数的影响。结果表明:法向力和转速会影响摩擦系统的Stick-slip振动特性;法向力会影响Stribeck模型中的动摩擦系数和衰减系数,转速则对静摩擦系数和衰减系数影响较大,对动摩擦系数影响较小。

带有两个物体的Burridge-Knopoff模型的stick-slip运动

Burridge-Knopoff模型是研究地震机理的一种摩擦动力系统模型。考察了具有两个自由度的Burridge-Knopoff模型的摩擦激振问题。系统带有两个摩擦接触面,摩擦采用带有负斜率的速度依赖型摩擦曲线。因为摩擦引入的非光滑性,给系统的直接求解带来了很大的困难;又因为具有两个摩擦接触面,运动情况会更加复杂:物体一的2种形式stick或slip,物体二具有同样的2种形式,从而可组合成4种运动形式的交替运动。首先找到各个运动形式的显式解,再根据各运动形式的跃迁点即可得系统总体的运动。在小的驱动速度下把速度依赖型的摩擦对速度取平均值,近似为动摩擦系数;把位移和速度表达为时间的显式函数。再按位移和速度处于不同运动形式进行迭代求解待定系数。最后由确定的待定系数判断系统运动的性质(周期运动或是混沌运动)。

A NEW CRITERION FOR OCCURRENCE OF STICK-SLIP MOTION IN DRIVE MECHANISM

This paper, using Karnopp's model of friction force and phase plane method, studies the stick-slip motion of the flexible drive mechanism. It is explained that a sudden drop of friction force is the essential source of stick-slip motion when the sliding is impending. A new criterion for occurrence of stick-slip motion is established. The stick-slip region and the stable region in a parameter plane are separated by a critical parameter curve. Moreover, for the stick-slip motion of the flexible drive mechanism without viscous damping, a parameter expression is obtained. The results may be used in design of the flexible drive mechanism.

Evolution of real contact area during stick-slip movement observed by total reflection method

We build an experiment system based on total reflection(TR) method to observe the evolution of real contact area of polymethyl methacrylate(PMMA) in the continual stick-slip movement. The bilateral friction is adopted to overcome the bending moment in the lateral friction movement. Besides some classical phenomena of stick-slip movement such as periodical slow increase of frictional force in sticking phase and a sudden drop when slipping, a special phenomenon that the contact area increases with the tangential force is observed, which was called junction growth by Tabor in 1959.Image processing methods are developed to observe the variation of the junction area. The results show that the center of the strongest contact region will keep sticking under the tangential force until the whole slipping, the strongest point undergoes three stages in one cycle, which are named as sticking stage, fretting stage, and cracking stage, respectively. The combined analysis reveals a physical process of stick-slip movement: the tangential force causes the increase of the real contact area, which reduces the pressure between the contact spots and finally leads to the slipping. Once slipping occurs,the real contact area drops to the original level resulting in the pressure increase to the original level, which makes the sticking happen again.

Simulation analysis on influential factors of stick-slip

In this paper a new physical model for studying stick-slip is established. Based on the dynamics system of the model,the state equation of the system is presented. And simulation analysis on the influential factors of stick-slip is carried out. The relationship between stiffness ( horizontal and normal) ,dampness,mass, difference of static and kinetic coefficients of friction,driving velocity,and amplitude in normal direction is analyzed and parameters of stick-slip are evaluated. Results show that stick-slip can be reduced by improving horizontal stiffness,decreasing dampness,reducing mass,cutting down the difference of static and kinetic coefficients of friction,properly choosing the vertical stiffness and properly inducting the normal oscillation.

Stick–slip behavior of Indian gabbro as studied using a NIED large-scale biaxial friction apparatus

This paper reports stick-slip behaviors of Indian gabbro as studied using a new large-scale biaxial friction apparatus, built in the National Research Institute for Earth Science and Disaster Prevention （NIED）, Tsukuba, Japan. The apparatus consists of the existing shaking table as the shear-loading device up to 3,600 kN, the main frame for holding two large rectangular prismatic specimens with a sliding area of 0.75 m^2 and for applying normal stresses an up to 1.33 MPa, and a reaction force unit holding the stationary specimen to the ground. The shaking table can produce loading rates v up to 1.0 m/s, accelerations up to 9.4 m/s^2, and displacements d up to 0.44 m, using four servocontrolled actuators. We report results from eight preliminary experiments conducted with room humidity on the same gabbro specimens at v = 0.1-100 mm/s and an = 0.66-1.33 MPa, and with d of about 0.39 m. The peak and steady-state friction coefficients were about 0.8 and 0.6, respectively, consistent with the Byerlee friction. The axial force drop or shear stress drop during an abrupt slip is linearly proportional to the amount of displacement, and the slope of this rela- tionship determines the stiffness of the apparatus as 1.15 × 10^8 N/m or 153 MPa/m for the specimens we used. This low stiffness makes fault motion very unstable and the overshooting of shear stress to a negative value was recognized in some violent stick-slip events. An abrupt slip occurred in a constant rise time of 16-18 ms despite wide variation of the stress drop, and an average velocity during an abrupt slip is linearly proportional to the stress drop. The use of a large-scale shaking table has a great potential in increasing the slip rate and total displacement in biaxial friction experiments with large specimens.

Microscopic Indicators of Stick-Slip and Creep-Slip in Deformation Products From the Daqingshan Piedmont Active Fault

Through the collection of oriented samples,consolidation of undisturbed samples,and systematic microscopy of thin sections,the deformation products from the Daqingshan piedmont active fault zone have been studied.The obtained results have been analyzed in combination with those of rock fracture experiments and macroscopic surveys.Based on the above,the present article summarizes the microscopic indicators of stick-slip and creep-slip,which reflect the characteristics of fault movement,and has given some suggestion on relevant problems.

Period Doubling Bifurcation of Stress Drop for Stick-slip and Its Physical Implication

It is revealed in frictional experiments on medium-scale samples that period doubling bifurcation of stress drop for stick-slip occurs due to macroscopic heterogeneity of the sliding surface under conditions for typical stick-slip.The observed data show that the period doubling bifurcation of stress drop results from the alternate occurrence of strain release along the whole fault and along part of fault.This implies that complicated nonlinear behavior corresponds to clear physical implication in some cases.

Observer-based State Feedback Control to Suppress Stick-slip Vibrations in Oil Well Drill-string

In drilling field, stick-slip vibrations of the drill-string are the main reason for the failure of the drilling system. To suppress the undesired stick-slip vibrations, an observer-based state feedback control method is proposed. The drilling system is described by a lumped parameter model including a Karnopp friction torque model. A state observer is designed to estimate the bit velocity in bottom hole and a state feedback controller is proposed to control the top drive velocity. By simulation, the performance of the control algorithm is demonstrated. Based on the control algorithm, a stick-slip vibration control system is developed. Test results show that the control system can effectively eliminate stick-slip vibrations of the drill-string and can be applied to the drilling field.

注塑中间轴Stick-slip噪音分析及改善方案

中间轴是转向系统中连接转向管柱和转向机可以传递扭矩并吸收路面激励的一种机械传动机构,车辆在启动和行驶中,转向系统由驾驶员实时操控,其噪音表现更直接被人们感知。转向注塑中间轴具有结构简单,制造工艺及成本低廉,综合性能优越。在车市竞争日趋降本争效的大环境下,越来越受到整车厂的青睐。由于是滑动副结构,两接触件相互摩擦易产生黏滑(Stick-slip)现象,注重介绍注塑中间轴结构及其在受载状态下的Stick-slip噪音分析和改善方案。

The structure features of stick-slip mechanism of the strike-slip earthquake generating structure in the interior of the Chinese mainland

This is the third one of the paper series on the strike slip earthquake generating structure in the interior of the Chinese mainland. The features of the tectonic stress field of strike slip earthquake generating structure were discussed in the first paper (Huan et al ., 1994), and the features of the deformation field of strike slip earthquake were presented in the second paper (Hun et al ., 1994). In the first section of this paper, through the analysis of the strike slip earthquake generating structure of several dozen large earthquakes with magnitude greater than 6.0, it is concluded that almost all strike slip earthquake generating faults are characterized by the oblique arranged distribution, and the barrier structure mode about the adhesive slip movement of strike slip is put forward; then in the second section, its four types, due to the different fracture form of the barrier at the ends, are also discussed; finally in the third section, the fracture terminating scale of the barrier of strike slip earthquake generating fault is also discussed.

Stick-Slip Tower-Shaped Piezoelectric Actuator

Since stick-slip actuators present the advantage of allowing long displacements(several centimeters or even more)at a high speed with an ultra high resolution(<5nm),a new type of stick-slip piezoelectric actuator is proposed to attain sub-nanometer positioning accuracy.The actuator is composed of a slider and a tower-shaped stator using forced bending vibration in y-z plane to generate tangential vibration on the top of the driving foot.When excited by the sawtooth input voltage,driving foot of the stator is able to generate a tangential asymmetrical vibration on the top,and the slider is thus pushed to move.A prototype and its testing equipment are fabricated and described.Following that,the testing of vibration mode and mechanical characteristics as well as stepping characteristics are conducted.Experimental results show that under the condition that the sawtooth input voltage is400VP-Pand the pre-pressure is 6N.Velocity of the actuator reaches its maximum 1.2mm/s at the frequency of 8000 Hz and drops to its minimum 35nm/s at the frequency of 1Hz.When the excitation signal is the single-phase sawtooth stepping signal,the tower-shaped actuator can directionally move forward or backward step by step.And when excited by the sawtooth stepping signal with 1Hz and 300VP-Pduring 1cycle(200ms),the actuator has a minimum stepping distance of 22 nm.

Study on Criterion About Overcoming Low-Speed Stick-Slip of Simulator

This paper sums up the research situation. At the influence of friction, a simulator exists the phenomenon of low-speed stick-slip. The character of low-speed of simulator is affected seriously. According to the phase plane method, algebra analyzing method and Lyapunov theory, the paper gives a criterion about overcoming low-speed stick-slip. Making use of the criterion, we can conclude the relationship between system parameters and low-speed stick-slip, and determine the condition where the parameters of PID controller should satisfy, for the purpose of overcoming low-speed stick-slip and has not the phenomenon of low-speed stick-slip. This method is simple and easy to carry out and the experiments show that the condition is correct.

Large Thrust Trans-scale Precision Positioning Stage Based on Inertial Stick-Slip Driving

For the smaller thrust,it is difficult to achieve 3Dtrans-scale precision positioning based on previous stick-slip driving.A large thrust trans-scale precision positioning stage is studied based on the inertial stick-slip driving.The process of the movement is divided into two steps,i.e.,the″sliding″phase and the″stickness″phase.In the whole process,the kinematics model of the inertial stick-slip driving is established,and it reveals some factors affecting the velocity of inertial stick-slip driving.Furthermore,a simulation of movement is preformed by Matlab-Simulink software,and the whole process of the inertial stick-slip driving is displayed.After one experimental prototype is designed,the back and forth velocity is tested.Finally,the simulation verifies the accuracy of the kinematics model.

Stokes flow before plane boundary with mixed stick-slip boundary conditions

A general theorem for the Stokes flow over a plane boundary with mixed stick-slip boundary conditions is established. This is done by using a representation for the velocity and pressure fields in the three-dimensional Stokes flow in terms of a biharmonic function and a harmonic function. The earlier theorem for the Stokes flow due to fundamental singularities before a no-slip plane boundary is shown to be a special case of the present theorem. Furthermore, in terms of the Stokes stream function, a corollary of the theorem is also derived, providing a solution to the problem of the axisymmetric Stokes flow along a rigid plane with stick-slip boundary conditions. The formulae for the drag and torque exerted by the fluid on the boundary are established. An illustrative example is given.

Slip-Stick Vibrations of Wheelsets and Rail Corrugations

A dynamic space coupling model is developed for simulating the vibrations of wheel/rail systems as well as the torsion and bending vibrations of wheelsets. It is found that the slip stick vibrations of wheelsets are mainly caused and controlled by the crossing excitation or self excitation of the vertical vibrations of the whole system and by the bending vibrations and torsion vibrations of the wheelsets. It is found for the first time that the slip stick vibrations may occur in more than one forms, and one or another of the three kinds of vibrations is excited more strongly. Four typical kinds of slip stick vibrations are enumerated and described. The field investigation on rail corrugations shows that the four kinds of slip stick vibrations are most likely to exist and related with different corrugated features.