The motion is governed by a static friction force in the stick phase and a velocity dependent kinetic friction force in the slip phase. The acoustic mechanics of stickslip friction in the. The mean braking force is where t is the stick slip cycle period. We have performed molecular dynamics simulations of nanomanipulation experiments on short singlestranded dna chains elastically driven on a graphene surface. During the static phase orange, frictional forces increase linearly until they reach the critical frictional force value f static when the slip phase blue starts. This process is continuously repeated while the objects are sliding. Stle members can access the paper for free by logging on to. Introduction in almost mechanical motion, friction appears in the sur. We argue that for a given external shear stress this system shows a discontinuous nonequilibrium transition from a uniform stick state to uniform sliding at some critical stress which is nothing but the griffith threshold for crack propagation. Controlling stickslip noise generation with lubricants.
A study of friction models and friction compensation. Analysis of stickslip motions has a fascinated researchers. Experimental investigations on stickslip phenomenon and. We discuss the stick slip motion of an elastic block sliding along a rigid substrate. Under certain conditions, a sliding motion between two surfaces does. Stick slip mitigation plan to improve drilling onepetro. Simply put, its the jerkiness that can plague both plain and recirculating linear bearings when they transition from standstill to motion. Stick slip motion of plain machine tool slideways has been simulated numerically 16. The pacific ocean plate goes down below the land plate and drags the latter. A continuous change from stick slip to stable sliding 3. Pdf dynamics of stickslip motion, whillans ice stream. Figure 2 flowchart 2 stick slip motion response 3 dynamic analysis and discussion the simulation required a few trials to determine the mass, damping and stiffness values which should be used with the. Web to pdf convert any web pages to highquality pdf.
Manipulating different drilling parameters as increasing the rotary speed, decreasing the weight on bit wob or modifiying the drilling mud characteristics as shown in the field to suppress stick and slip motion p. Use pdf download to do whatever you like with pdf files on the web and regain control. Static plates induce crystalline order in the film. Stick slip motion and high speed ejection in granular avalanches detected through a multi sensors flume. Eliminate artifact lines with consistent linear motion demystifying the 21 ratio and stick slip phenomenon integralv linear guide system vs re. Frictional vibrations are phenomena, which take place between contacting surfaces with relative motion and their wear occurs by friction 8. Investigating glacier stickslip motion using a wireless. Slipstick makes the cello beautiful and the squeaky door annoying. The cycles have the periodicity of the graphene substrate, and take place via an intermediate.
The distributions of both jumps and duration times were found to follow powerlaws spanning up to 3 orders of magnitude. Dynamics of contact areas true contact areas change as a result of both relative motion of surfaces and deformation of asperities during this motion. Stickslip motion involves periodic shearmelting transitions and recrystllization of. Stick slip refers to the fast movement that occurs between two sides of a fault when the two sides of the fault become unstuck. To the unaided eye the motion of sliding objects appears steady. A theoretical investigation of frictioninduced selfexcited oscillations for systems with one degree of freedom is proposed. Stick slip friction is generally described as a composite of two different. Other examples of stick slip friction include noises made during honing, heavy braking and screeching tires or chalk on a blackboard. The dynamic analysis of stickslip motion sciencedirect. How to measure, prevent, and eliminate stickslip and noise. Submicron strain analysis o local stickslip motion o. When the rock snaps back into an unstrained position it is called elastic rebound. However, velocity reversal is observed during stick slip motion of a laboratory test rig with oil lubricated centrepivoted sliding shoes and a very flexible.
Influence of spring constant on stick slip behaviour static friction in the previous section, the negative slope of. Video of simple stickslip motion in sliderblock model. The rock becomes distorted, or bent, but holds its position until the earthquake occurs. Usually, no velocity reversal occurs during the slip phases of a stick slip cycle. Identification and quantification of stickslip induced. The decrease of the applied weight on bit or an increase of imposed velocity o. Click here for free access to our latest coronaviruscovid19 research, commentary, and news. The paper explains how merchants basic theory has been applied to an improved slideway test apparatus which, by the use of standardized procedures, produces an accurate measurement of the stick slip. Stick slip, also referred to as stiction, is the bane of engineers and machine builders who need smooth, precise motion.
Friction, stickslip motion and earthquake springerlink. Frictional force measurement during stickslip motion of a. Stickslip motion of moving contact line on chemically. Torsional stick slip and lateral whirl vibrations in bha scaled model duration. Animation for stick slip motion of mass on moving belt for different values of static friction coefficient. A in steady sliding systems, the kinetic friction force f kinetic is measured once the system reaches a constant sliding velocity. The frictional properties of a lubricant are critical to i. Read online submicron strain analysis o local stick slip motion o. Stick slip friction is present in any elements involving relative motion, such as gears, pulleys, bearings, dc motors.
The rigid block is free to move both in normal and. Using a dynamic analysis it is shown that the rate of increase of. Dynamic modeling of stick slip motion in an untethered. Drillstring vibrations and vibration modeling product sheet. Occasionally, the science is dense, but when readers need clarification, scholz offers bracing metaphors. In reality this motion is jerky or intermittent because the objects slow during shear periods and accelerate following the shear. Hysteresis phenomena in the stickslip motion at the. Friction models for precise positioning system in machine tools and their numerical validations are investigated 17. The stickslip motion is almost periodic for spherical particles over a wide range of. Mechanical models of friction that exhibit hysteresis, stick slip, and the stribeck e. Driving forces are assigned with two functions,one appropriate for comparison with the test and the other to study stick slip orbits, which have been found to have various types of motion depending on the controlling brake actuation parameters.
Stick slip is often seen while drilling and is a severe form of drillstring torsional oscillation in which the bit becomes stationary for a period. The most widely accepted cause of stick slip motion is that the static. That is, the motion of the sandpaper consists of varying distance and time. His direct, brisk narrative likewise adeptly portrays the various sides in. Below is a simple, heuristic description of stick slip phenomena using classical mechanics that is relevant for engineering descriptions.
Minirod stick slip motors piezo inertia motors are based on a small piezo element moving along a rod when driven with a quasi sawtooth signal. Pdf origin of stickslip motion in a driven twowave. This work is an attempt to design and fabricate a simple and compact piezoelectric walker integrated with a force sensor to measure the frictional force during the slip phase. In this paper we show that the continuum predictions can be quantitatively veri. Pdf investigate stickslip intervals with one equation of motion. As the severity of stick slip increases, the length of the stuck period increases, as do the rotational accelerations as the bit breaks free fig. For a broad range of parameters, a generic stickslip motion is observed, consistent with the results of recent boundary lubrication experiments. Computer simulations of motion of mechanical systems with. When the bow is moved over the strings or the grasshopper rubs its legs together, the vibrations that result from stick slip motion cause characteristic sounds. All books are in clear copy here, and all files are secure so dont worry about it. After a brief transient, reproducible stick slip cycles are observed on chains made by 10 units of thymine, cytosine, adenine, and guanine. When the hydrodynamic decay length the viscous wave penetration depth is larger than. Thus braking effectiveness is reduced by stick slip. Stick slip is generally a dynamic cyclic process where two mating surfaces oscillate between a stick phase and a slip phase.
A stick phase slow enough to transfer motion, is followed by a very rapid slip phase where the piezo element retracts but the load cannot follow. From practice, on the other hand, it is known that a stiffer link may help to avoid oscillating friction. Download submicron strain analysis o local stick slip motion o. How to measure, prevent, and eliminate stickslip and. Stick slip is the wellknown phenomenom of intermittent motion caused by a changing friction force in combination with mechanical system elasticity. Stickslip vibrations induced by alternate friction models. The stickslip phenomenon, also known as the slip stick phenomenon or simply stick slip, is the spontaneous jerking motion that can occur while two objects are sliding over each other. The backward motion of the actuator during the slip phase due to the stiffness alters the motion of any stick slip friction principle based positioners drastically. Timeresolved studies of stickslip friction in sheared.
In the slip phase, there is finite relative motionsocalled kinetic friction acts. An inhomogeneous mode of sliding occurs when the driving velocity. The friction force is assumed as an odd function of the relative sliding velocity with a jump discontinuity at a value of zero for the relative sliding velocity. The friction characteristic is approximated with a piecewise linear function, i. Stick slip mitigation option tree highsevere stick slip 1 pdc bit 4 increase mud 2 bha 3 drilling parameters lubricity more bladessmaller cutters increase cutter backrake angle depth of cut limitershybrids use insert bit drop flex collar undergauge stabilizers 18 to 116 integral blade or melonprofile stabilizers drop. All experiments are gouge free, conducted with bare roughened salt sliders. Molecular dynamics simulations of atomically thin, fluid films confined between two solid plates are described. In this paper we develop a non linear observer in order to estimate the friction force of the contact during the motion, and to compensate its effects which causes the stick slip phenomenon. In the stick phase, the two surfaces are not in motion and are held in place by socalled static friction. Origin of stickslip motion in boundary lubrication science. Stickslip motion of ssdna over graphene the journal of. The first page of the pdf of this article appears above. If instead of stick slip motion the brake remained at rest at the equilibrium position then. Dynamics of stick slip motion, whillans ice stream, antarctica.
442 1083 770 1206 184 606 1468 1554 1308 1419 1114 156 1091 1380 823 1500 663 669 124 1585 510 1371 1147 1084 64 1332 625 13 577 993 336 556 1057 690 1218 685 1189 421 122