Rotational Friction Research Articles

Modeling lateral vibration of bottom hole assembly using Cosserat theory and laboratory experiment verification

Lateral vibrations are a complex form of vibrations that may occur while drilling. The understanding of their motion has been relatively comprehensive; however, further studies on their internal mechanisms are required. Existing dynamics models of the drill string are difficult to apply owing to the large number of assumptions and simplifications. The curved elastic rod described by the Cosserat theory can be used as an ideal model to study the motion and mechanical characteristics of drill string because of its large deformation and extreme slenderness. On the basis of existing research, this study proposes a comprehensive drill string dynamics model based on the Cosserat theory. The model is applied to study the lateral vibrations of a bottom hole assembly (BHA), considering factors such as the mass eccentricity, material viscosity, and weight-on-bit (WOB). The established model and experimental device were used to conduct simulations of specific schemes and examine the lateral vibrations of the BHA under the influence of the deviation angle, rotational speed, WOB, and friction coefficient. The accuracy of the established model and its generality were verified by comparing the data from theoretical calculations and experimental simulations. The results demonstrate that the lateral vibrations of the BHA in a nonvertical well indicate the reciprocating oscillation located at the lower right side of the wellbore. The amplitude of the lateral vibration can be increased by reducing the deviation angle or increasing the rotational speed and the friction coefficient. In a vertical well, the BHA exhibits forward whirl, irregular motion, and backward whirl as the rotational speed and friction coefficient increase. Increasing the WOB has insignificant effect on the lateral vibrations of the BHA at the maximum WOB value achieved by the experimental device. However, further increasing the WOB in the theoretical calculation could cause the buckling and backward whirl of the BHA in a vertical well.

Influence of the heating force in rotational friction welding on mechanical properties and tensile fracture mechanism of dissimilar welded joints of 30KhGSA and 40KhMFA steels

This article presents the results of evaluating the effect of heating force, as one of the parameters of rotational friction welding, on the mechanical properties and mechanism of tensile failure of dissimilar welded joints of medium-carbon steels 30KhGSA and 40KhMFA. The results of studies of the microstructure and microhardness of welded joints are presented. The fracture mechanism of welded specimens during tensile testing was evaluated on the basis of strain distribution maps obtained by the digital image correlation method and the results of fractographic analysis. The features of the development of deformation and failure of welded joints obtained at different heating forces are shown. From the point of view of the equal strength of the structure with a welded joint the optimal values of this parameter of rotary friction welding for joining steels 30KhGSA and 40KhMFA are recommended.The reported study was funded by RFBR according to the research project № 20-38-90032.When conducting mechanical tensile tests and studying the distribution of deformation fields, equipment was used that is part of the Plastometriya collective centre of the IES named after E. S. Gorkunova of the Ural branch of the RAS

Retrofitting of a Precast Reinforced Concrete Industrial Building Using Friction Dampers Without Stopping Functionality

This paper presents a seismic retrofit of an industrial-type precast reinforced concrete building structure using friction dampers. This project consisted of retrofitting two precast reinforced concrete buildings, of which one of them will be presented here. Precast concrete is one of the most preferred methods of construction for industrial structures due to its low cost, fast construction and availability in rural areas. Unfortunately, most structures constructed before “Specification for Buildings to be Built in Seismic Zones(TBDY 2018)” are not sufficiently engineered and are expected to have poor performance when exposed to a major seismic event. Because stopping the production cost can be tolerated by the owners, a retrofitting technique that can be assembled during normal function of the industrial structures is required. As a result of this requirement, friction dampers are selected as the supplemental energy dissipation device. ASCE 41-17 [10] is employed for the damper design and performance evaluation of the building. Before the damper study, some instability and weak connection problems are solved by some traditional measures of strengthening. The most effective damper configuration and capacities are selected after an iterative trial-and-error linear study using the simplified methods developed by PROMER. Nonlinear push-over analysis are conducted after linear prestudies. Finally, a nonlinear time-history analyses is performed for confirmation of the results. , It is shown that the proposed retrofit scheme satisfies the desired performance goals for both DBE and MCE events. Overall, it is considered that proposed retrofit scheme with dampers provides the optimal solution for the stakeholders of the project from a performance, design, constructability, and economical point of view. Some application photos will be presented and methods are explained in detail in the paper. The friction damper behavior is based on the rotational friction hinge concept

Light metal modification and composite preparation by a new solid-state processing process: Rotational friction extrusion

The light metal modification and composite preparation were achieved by a new solid-state processing process referred to as rotational friction extrusion (RFE) which is self-developed. The Al modified by RFE (RFEed Al) exhibited equiaxed grains with an average grain size of 17.5 μm and a high fraction of high-angle grain boundaries of 70.7%. The added reinforcement exhibited good dispersity in the fabricated Al matrix composite (AMC). The ultimate tensile strength (UTS) of the RFEed Al was only ∼20 MPa lower than that of the base metal, while the uniform elongation significantly increased from 2.1% of the base metal to 27%. Moreover, the AMC also displayed superior mechanical improvement, wherein the UTS and uniform elongation was 214.7 MPa and 13.5%, respectively. This new solid-state processing process is suitable for light metal modification and composite preparation.

Experimental determination of the propulsion matrix of the body of helical Magnetospirillum magneticum cells.

Helical-shaped magnetotactic bacteria provide a rare opportunity to precisely measure both the translational and rotational friction coefficients of micron-sized chiral particles. The possibility to align these cells with a uniform magnetic field allows clearly separating diffusion along and perpendicular to their longitudinal axis. Meanwhile, their corkscrew shape allows detecting rotations around their longitudinal axis, after which orientation correlation analysis can be used to retrieve rotational diffusion coefficients in the two principal directions. Using light microscopy, we measured the four principal friction coefficients of deflagellated Magnetospirillum magneticum cells, and compared our results to that expected for cylinders of comparable size. We show that for rotational motions, the overall dimensions of the cell body are what matters most, while the exact body shape has a larger influence on translational motions. To obtain a full characterization of the friction matrix of these elongated chiral particles, we also quantified the coupling between the rotation around and translation along the longitudinal axis of the cell. Our results suggest that for this bacterial species cell body rotation could significantly contribute to cellular propulsion.

Numerical modeling for the mechanism of shoulder and pin features affecting thermal and material flow behavior in friction stir welding

A three-dimensional transient computational fluid dynamics model is developed to analyze the influence of rotational/non-rotational shoulder and pin characteristics on the thermal and material flow behavior in friction stir welded (FSW) aluminum alloy joints. Four tool designs with rotational/non-rotational shoulder and the pin with/without triple facets are considered. The heat cycle of the rotational and non-rotational shoulder friction stir welded joint (RS-FSW and NRS-FSW) is simulated and experimentally verified, and the welding temperature fields are analyzed. The welding peak temperature of the RS-FSWed joint is the highest, and the non-rotational shoulder significantly reduces the welding peak temperature and the range of the heat-affected zone (HAZ). The rotational shoulder promotes material flow and enhances flow velocity, whereas the non-rotational shoulder reduces both. An increase in the triple facets on the pin facilitates the material flow during NRS-FSW. Viscosity is a physical quantity associated with the welding temperature and strain rate, which is affected by the tool characteristics. The deformation zone caused by the tool is related to the viscosity of the material, the closer the tool, the lower the viscosity of the material. The viscosity of the material gradually increases with an increase in the distance from the tool surface.

Performance analysis of GA, PSO and JA for determining the optimal parameters in friction drilling process

The friction drilling process, a technique for making sheet metal holes, differs from the conventional drilling process. Instead of cutting the workpiece, this process forms bush by using high heat generated at the contact region of the rotating conical tool and work material. The surface quality of the bush is not like a shiny and smooth surface due to the generation of high heat energy. Experimental investigation of friction drilling process has been done for optimization of surface roughness and bushing length by various researchers. This research work attempts application of meta-heuristics such as Genetic Algorithm (GA), Particle Swarm Optimization (PSO) and Jaya Algorithm (JA) and compares the results in order to evaluate their performances. GA, PSO and JA are applied to minimize the surface roughness of the friction drilled holes which depends on parameters viz rotational speed, friction angle and workpiece thickness. Also, these algorithms are applied to maximize bushing length by considering the significant parameters viz friction angle, friction contact area ratio, feed rate and spindle speed. The results are compared for surface roughness value and bushing length signal to noise ratio. The comparative analysis shows that the Jaya algorithm performs more efficiently with quick convergence to the solution compared to other two algorithms. The comparison of PSO with GA shows that, the PSO performs better in terms of convergence to the solution for both the objectives. Further, it has been found that JA shows the robustness in terms of consistency of results for different population sizes and number of iterations.

Tribological Properties and Seasonal Freezing Damage Evolution of Rotating Spherical Hinge Self-Lubricating Coating

The spherical hinge is an important part of rotating bridge construction, but over a long period of time, spherical hinge self-lubricating coating is easily eroded by water vapor. In this paper, the tribological properties and seasonal freezing damage evolution characteristics of a variety of rotating spherical hinge self-lubricating coating materials were studied by means of friction coefficient measurement experiments, friction and wear experiments and shear rheological experiments based on a self-developed indoor spherical hinge rotational friction coefficient tester. The results show that the self-developed indoor spherical hinge rotational friction coefficient tester can effectively and truly represent the working state and tribological properties of self-lubricating coating in practical engineering. A seasonal freezing environment has obvious influence on the tribological properties of spherical hinge self-lubricating coating, which is an irreversible process of deterioration. With the increase in the freezing–thawing cycle, the friction coefficient and viscosity of self-lubricating coating materials increase gradually, and the thixotropy and elastic recovery become worse and worse. When the content of graphene is 0.1%, the performance is the best. At room temperature and in a freeze–thaw environment, the friction coefficient of graphene grease is lower than that of PTFE 0.007 and 0.008, respectively. The diameter of the grinding plate is less than 0.075 mm and 0.001 mm, respectively. The maximum bite load without card is higher than 8.1% and 11.5%. The area of the thixotropic ring is lower than 41% and 42%. Phase transition points were higher than 42% and 64%. The apparent viscosity was higher than 6.6% and 74%. Graphene greases show the greatest bearing capacity, thixotropy and structural strength in conventional and seasonal freezing conditions and exhibit excellent tribological properties.

High entropy alloy reinforced aluminum matrix composites prepared by novel rotation friction extrusion process: Microstructure and mechanical properties

A novel rotation friction extrusion (RFE) process was taken to fabricate CrMnFeCoNi high entropy alloy (HEA) particles reinforced aluminum matrix composites (AMCs). The experimental methods and the first principle calculation based on density functional theory were employed to study the microstructure and mechanical properties of the composites. Results showed that the HEA particles reacted violently with the aluminum (Al) matrix during RFE. The average grain size of the AMCs was 3.6 μm, which was significantly lower than that of the RFEed Al (13.2 μm). Numerous second phases with FCC structure were formed, as a result of the large thermodynamic driving force and the enhanced element interdiffusion. The tensile strength of the AMCs showed substantially enhanced compared to that of RFEed Al, which could be ascribed to load transfer, dislocation strengthening, fine-grained strengthening and Orowan strengthening. The uniform elongation of the AMCs was lower than that of the RFEed Al, which was explained by the fine grain size of the AMCs resulting in high dislocation dynamic recovery rate.

Pullout Resistance of Densified Wood Dowel Welded by Rotation Friction

Pullout Resistance of Densified Wood Dowel Welded by Rotation Friction

Soil-structure interaction effects on the seismic performance of steel moment-resisting frames equipped with optimal rotational friction dampers

This study investigate the soil-structure interaction (SSI) effects on the seismic performance of steel moment-resisting frames (SMRF) equipped with optimal rotational friction dampers (RFDs). Firstly, a simultaneous optimal design based on the energy concepts is expanded to find the optimal placement and the corresponding optimal parameters of the RFDs for the seismic protection of a nonlinear six-story SMRF. Then, the direct method is adopted to simulate the nonlinear SSI effects on the optimal RFDs-equipped SMRF. The input, hysteretic, dissipated energies and the drift of stories of the controlled SMRF subjected to four real earthquake excitations indicate that SSI can considerably influence the seismic performance of the controlled SMRF. Nevertheless, the significant amount of the seismic input energy is dissipated by optimal RFDs and therefore its limited amount is dissipated by the structural. Moreover, the optimal RFDs can maintain the story drift ratios within the acceptable drift limits.

Friction variable rubber pad using magnetorheological elastomer for robot grippers

This paper is focused on developing a friction-variable rubber pad using magnetorheological elastomer (MRE) for robot gripper applications. Tribological experiments were conducted on the designed rubber pad to analyze the friction variation on various surface types such as plastics, aluminum, and glass. Experimental results showed that the frictional coefficient can be varied as much as 40% when a magnetic field of 250 mT was applied. Furthermore, prototypes of robot grippers with MRE pads were manufactured and tested to analyze the translation and rotation friction force control in grabbing, releasing, and turning an object. Experiments confirmed that the proposed robot gripper pad can control the overall friction force by more than 48%, validating the applicability of the MRE pads for robotic applications.

Moiré-Pattern Evolution Couples Rotational and Translational Friction at Crystalline Interfaces

The sliding motion of objects is typically governed by their friction with the underlying surface. Compared to translational friction, however, rotational friction has received much less attention. Here, we experimentally and theoretically study the rotational depinning and orientational dynamics of two-dimensional colloidal crystalline clusters on periodically corrugated surfaces in the presence of magnetically exerted torques. We demonstrate that the traversing of locally commensurate areas of the moir\'e pattern through the edges of clusters, which is hindered by potential barriers during cluster rotation, controls its rotational depinning. The experimentally measured depinning thresholds as a function of cluster size strikingly collapse onto a universal theoretical curve which predicts the possibility of a superlow-static-torque state for large clusters. We further reveal a cluster-size-independent rotation-translation depinning transition when lattice-matched clusters are driven jointly by a torque and a force. Our work provides guidelines to the design of nanomechanical devices that involve rotational motions on atomic surfaces.

Selective laser melting of WC-Co reinforced AISI 1045 steel composites: microstructure characterization and mechanical properties

Due to the limited wear resistance, AISI 1045 steel has limited applications in harsh environments, and the friction effect leads to premature scrapping. In order to improve the mechanical properties of AISI1045 steel, in this study, WC-Co particles reinforced AISI 1045 steel composites were produced by selective laser melting (SLM), and mainly focused on the influence of laser line energy density (LED) on the microstructure and mechanical properties in detail. The Vickers hardness test and rotational friction test were conducted to determine the Vickers hardness and friction resistance properties of composites. Results demonstrated that the SLM 500 J/m WC-Co/AISI 1045 steel composites possesses higher Vickers hardness and wear resistance compared to that of other samples owing to the finer grains and higher relative density. Herein, the wear mechanism and the binding interface of the SLM composites was also deeply discussed in this paper.

A dry-connected rotational friction dissipative beam-to-column joint for precast concrete frame: full-scale experimental and numerical investigations

Simplifying the configuration, enhancing the energy dissipation capacity and achieving the adjustable performance are critical challenges in development of dry-connected beam-to-column joint. To address these, a dry-connected rotational friction dissipative beam-to-column joint (DRFDBJ) for precast concrete (PC) frame structures is developed with simple detail and adjustable performance, as well as desirable deformation capacity and energy dissipation capacity. Three solutions concerning the details and assembly sequences are recommended to ensure the expected performance. To validate the performance of the DRFDBJ and the effectiveness of the three solutions, full-scale experimental and numerical investigations were conducted. The results indicated that the desirable seismic performance of the DRFDBJ, including the damage mechanism, load-bearing capability, deformation capacity and energy dissipation capacity, were validated. The adjustable performance of the DRFDBJ was successfully achieved through accurate control of the corresponding yield load. The proposed three solutions were verified to be critical for achieving the target performance of the DRFDBJ. The research outcome can provide a valuable reference for the development of dry-connected beam-to-column joints for PC frame structures.

Numerical analysis of drill string whirl for vertical well based on rolling model and small-strain shell element

Whirl is a kind of serious lateral vibration. Accurate numerical simulation of whirl for drill string is important for drilling engineering. In this study, a new finite element (FE) model using shell element is established, which can accurately describe the whirl and realize the visualization of motion. Rolling model of drill string in the borehole is proposed. Kinematic contact with clearance, Coulomb friction model and initial imperfection are considered in this model. The explicit dynamic method is selected to solve the convergence difficulty caused by complex contact between shell elements. Compared with the experiment results, the accuracy and reliability of the model are verified. Meanwhile, the effects of rotation speed, friction coefficient, weight-on-bit (WOB) and clearance between the drill string and the borehole wall on the whirl of vertical wells are also studied in the numerical simulation. The rotation speed and friction coefficient have an obvious positive effect on the random motion and backward whirl of drill string: The continuous increase of rotation speed or friction coefficient can cause backward whirl, after that, velocity, acceleration of drill string, contact force and friction will increase significantly. When the rotating speed increases from 400 rpm to 800 rpm, the whirling speed increases by 160%, the average friction and contact force increase by 290%, which is much higher than the increase of 100% of the rotating speed. Instead, WOB has little influence on the drilling parameters mentioned-above and the variations of average friction and contact force for different WOB does not exceed 10%. In addition, properly increasing the distance between the drill string and the borehole wall will make backward whirl easily occur. However, when the clearance is large enough, there will be no contact and the drill string will make irregular non-contact forward whirl. What's more, forward whirl has a positive impact on eccentric wear, and backward whirl reduces WOB transmission and increases risk of sticking. Therefore, drill string whirl should be reasonably utilized or its harm should be reduced in practical drilling engineering.

Modelling rotational friction damping devices using the Non-Smooth Dynamics method

The dynamic response of frames equipped with an anti-seismic rotational friction damper is studied. The algorithm of the Non-Smooth Dynamics method (NSD), specifically designed for the numerical simulation of non-smooth dynamical systems, was programmed to efficiently deal with the non-smooth character of the friction law. An extensive campaign of numerical computations was carried out to study different frames, either submitted to a harmonic excitation force or to the ground acceleration history of the El Centro earthquake. Each friction damper has two prestressed bracing bars; the cases of axially rigid and axially compliant bracing bars were considered. Performance criteria enabled to conclude on the optimal range for the maximum moment at the frictional hinge of the damper. For the analyzed frames of one, three and five floors and for both rigid and deformable bracing bars, under the action of the El Centro earthquake, it was concluded that the optimal range for the frictional moment is wide and approximately independent of the number of floors. An important reduction of the relative displacements and absolute accelerations of the floors of the frames with friction dampers was observed with respect to the situation of absent frictional damping.

Development of CubeSat Magnetic Torquer Testing System in a Vacuum Environment

This paper discusses the development and instrumentation of an integrated facility based on an air-bearing table to test small ADCS actuators such as electric propulsion devices, reaction wheels, and magnetic torquers for CubeSats. It includes an automatic balancing system that corrects the center of mass of the testing platform and a Helmholtz cage for the simulation of the in-orbit geomagnetic environment inside the vacuum environment. Through experimental tests, it was observed that the attitude disturbances due to the aerodynamic drag and the viscous rotational friction in atmospheric conditions (~5×10-6 Nm) can be significantly decreased when the testing platform is placed inside a vacuum environment (~5×10-7 Nm). It was also observed that the vacuum condition facilitates the verification test of attitude control maneuvers using small magnetic torquers for CubeSats whose control torque is smaller than the attitude disturbance torque in atmospheric conditions. A demonstration test was performed to verify the attitude stabilization control by the magnetic torquers in vacuum conditions under a simulated geomagnetic field as in the International Space Station orbit using this integrated testing facility.

A rotational friction damper-brace for seismic design of resilient framed structures

In the present study, a ductile bracing system is proposed which has a rotational friction damper joint with an eccentricity from the diagonal of the bay. Similar to other seismic energy dissipation devices, the developed system can be used for seismic design of new structures, where other structural elements remain elastic during earthquakes, as well as for seismic retrofit of existing structures. The structural behavior of this system is studied thoroughly using theoretical approaches and a seismic design procedure is provided. The formulations are verified by establishing an analysis model of the system and comparing the theoretical and analytical results. A ductility-based design procedure is provided for structures using this system and an illustrative three-dimensional structure is designed and analyzed in detail using various analysis methods. The results show that the proposed damper-brace system and the design process can be efficiently used in practice.

Research on Monitoring Method of Mechanical Joint Rotational Friction in Bench Press Training

Bench press training seems to be the most common exercise for increasing upper-body strength and control among athletes, fitness enthusiasts, and wellness buffs. Bench presses are usually done by lying down on the bench with the back, shoulders, and buttocks in touch. The bench press training surveillance systems with technical advancements are rarely seen in the research domain. Therefore, this paper presents a novel bench press training monitoring method (BPTMM) by evaluating mechanical joint rotational friction using Internet of Things (IoT) sensors. The bench press is a common upper body strength-building and muscle-building conditioning exercise. The bench press and the squat and deadlift are the three primary lifts performed in powerlifting competitions. Artificial intelligence aids in risk prediction and suggests possible positions. There is a 96.8% accuracy rate in surveillance and categorization, according to the findings of the experiments.