Friction-induced Vibration Research Articles

Friction-Induced Vibrations of a Two DOF Self-Excited SD Oscillator

Friction-Induced Vibrations of a Two DOF Self-Excited SD Oscillator

Self-excited vibration suppression of a spline-shafting system using a nonlinear energy sink

The rotating instability and corresponding non-synchronous vibrations seriously affect the long-term operations of modern high-speed rotating machinery. However, there is still a lack of effective control methods to prevent the unstable vibration of the rotor system. This study focuses on the effective suppression of large-amplitude self-excited vibrations in spline-shafting systems using a nonlinear energy sink (NES). A nonlinear dynamic model for a spline-shafting system incorporating the non-smooth friction interface is developed. The corresponding friction-induced vibration and the instability mechanism are explored through the time-frequency analysis. The NES is then employed for the self-excited vibration suppression and the optimum parameters of the NES are obtained through the rotor vibration response surface. Several numerical analyses are conducted to investigate the suppression performance of the NES under the condition of different load torque. Lastly, the mitigation of the rotor self-excited vibration is realized and the mechanism of NES suppressing self-excited vibration by strong modulated response is elucidated. The obtained results show that the NES can not only effectively reduce the vibration of the rotor system in the vicinity of resonance, but also alleviate the large amplitude of self-excited vibration simultaneously, which may provide helpful guidance for the dynamic design of complex rotor systems.

Friction-induced vibration and noise characteristics, and interface tribological behavior during high-speed train braking: The effect of the residual height of the brake pad friction block

A tribology test was carried out on a test device to simulate the braking performance of a high-speed train and investigate the effect of the friction block's residual height on friction-induced vibration and noise (FIVN) characteristics and interface tribology behavior. A finite element model (FEM) of the test device was established using the real boundary conditions and component material parameters. A wear simulation of the friction block was performed, and the Archard wear equation was used to obtain the surface wear of the friction block after stable friction had occurred. Complex eigenvalue analysis (CEA) and implicit dynamic analysis (IDA) were carried out. The effect of the friction block's height on the surface wear level, the complex mode and dynamic response, and the interface contact behavior are discussed. The results show that the friction block wears at an angle due to the friction force at the braking interface. Thus, the contact stress occurs predominantly at the leading edge of the friction block, leading to significant wear, high temperatures, and eccentric wear of the friction block. The taller the friction block, the larger the inclination angle is, and the more significant the eccentric wear degree is. Excessive wear at the leading edge causes debris to enter the brake interface. As a result, the wear surface of friction block is significantly damaged, including large contact plateaus and extensive exfoliation and ploughing. This damage increases the complexity of the braking interface's tribological behavior and causes high-intensity FIVN. However, the inclination angle decreases as the friction block's height decreases, resulting in better wear behavior of the friction interface and lower FIVN intensity. Although the friction block height significantly affects the intensity and evolution of FIVN, it does not change the system's inherent frequency.

Friction-induced Vibration Reduction and Energy Harvesting of High-speed Train Brake Interface

Friction-induced Vibration Reduction and Energy Harvesting of High-speed Train Brake Interface

Mechanism of Friction-induced Vibration of Rubber Materials and its Countermeasures

Mechanism of Friction-induced Vibration of Rubber Materials and its Countermeasures

Cascade architecture for nonlinear control of transient and stationary regimes of friction-induced vibrations

This paper presents a new control approach for mitigating friction-induced vibration (FIV) issued from the mode-coupling mechanism. The key idea is to put the friction system onto a cascade of independent subsystems by using a first-stage control. Then, a second-stage control is defined and proven to be much more efficient for controlling both the transient and stationary regimes of the FIV. Asymptotic stabilization is formally demonstrated for the whole control scheme. Moreover, by numerical simulations, it is shown that the performances of the closed-loop systems present an interesting robustness with respect to parameter uncertainty and to the saturation phenomenon which opens up promising practical perspectives for the proposed control technique.

Active control for stick-slip behavior of the marine propeller shaft subjected to friction-induced vibration

A stable rotational speed of the marine propeller shaft is essential to minimize the friction of the supporting bearings and to improve the efficiency of the power system. While, the friction induced vibration of the marine shaft-bearing system seriously affect the performance and reliability of the powertrain. This paper proposes an active control method to suppress the stick-slip behavior of the marine propeller shaft based on state observer. The dynamical response including relative velocity, power spectral density, dynamic friction coefficient and reaction force with various friction model are calculated. The active control with state feedback and internal model principle are applied to track the rotational speed of each segment of the whole shaft. The behavior of the state observer is analyzed through a comparison of actual value and observed value of the tracking for continuously varying speeds. The robustness of controlled system is investigated through comparison of overshoot rate and adjustment time with various control parameters. Moreover, a comparison of the observed velocity between present work and previous reference is conducted to validate the applicability of the proposed frictional model. The active control for friction-induced vibration of marine propeller shaft is thus realized based on the adjustment of control parameters.

Probing the effect of the electric current on the tribological performances of the electrical contact surfaces with graphene coating

A simple and effective method is used to construct graphene coating on brass surface, and the effect of electric currents on tribological performances are studied. Results show that larger current can reduce the friction coefficient and contact resistance, moreover, larger current can suppress the generation of friction-induced vibration. Surface analysis results show the graphene coating is seriously damaged at a low current input, result in the increase of friction coefficient and generation of vibration. Numerical analysis results suggest a larger input current can help reduce the contact pressure and accordingly improve the wear. Moreover, larger current causes the graphene coating to expand, leading to a better contact with the friction pair, so the graphene can better exploit its properties.

Use of probabilistic fastener velcro as a friction-induced vibration damping treatment

Probabilistic fasteners are biologically inspired clamping devices that are interlocked by stems on each surface. Due to dynamic characteristics of fastening mechanism, friction inevitably occurs between stems in a vibrating environment. The use of the probabilistic fastener as a vibration reduction component were investigated with advantages from friction-induced damping in this study. The dynamic stiffness and loss factor of the probabilistic fastener were derived from the vibration interaction with a mechanical structure. This allowed determination of energy dissipation due to the friction in hook and loop from the wave propagation analysis. As the vibration amplitude increased, the loss factor of the fastener gradually increased because the friction between multiple stems increased. With the probabilistic fastener application, the vibration generation and transmission were reduced compared to the bolted joint due to the inherent frictional contacts. With this unique advantage, the probabilistic fastener has potential applications when large damping is required with additional benefit on the reduced weight.

Tribological and Friction-Induced Vibration Behaviors of Inorganic Fullerene-Like Tungsten Disulfide and Three-Dimensional Graphene as Lubricant Additives

Abstract Friction and friction-induced vibration have a great impact on the service life of mechanical systems. In this study, the tribological performances and vibration characteristics of three-dimensional graphene nanosheets (3D GNS), inorganic fullerene-like tungsten disulfide (IF-WS2), and their mixed additive lubricants are investigated by experiments. The results show that IF-WS2/3D GNS (1:1) mixed additive can improve the friction-reduction and anti-wear of base oil by 62.9% and 71.4%, respectively. In terms of vibration damping, the mixed additive has an extremely strong dampening effect on vibration acceleration in all directions, especially in the Z-axis direction, where the amplitude is reduced by about 90%. The vibration damping should be attributed to the filling effect of 3D GNS and IF-WS2, which greatly flattens the friction surface, thus reducing the number of collision micro-bumps in the relative movement of the friction pair and suppressing the vibration. In addition, the unique ductile deformation of IF-WS2 makes the two additives form a flexible ball-bearing damper between the two contact surfaces, thus greatly reducing the vibration.

The roles of T-ZnOw and MoS2 particles in the friction-induced vibration reducing the process of polymer

A novel thermoplastic polyurethane (TPU) matrix composite was combined with tetra-needle zinc oxide whisker (T-ZnOw) and molybdenum disulfide (MoS2) particles. Frictional vibration experiments were conducted to study the effect of T-ZnOw and MoS2 particles on frictional vibration behaviors. The tribological properties and vibration behaviors of TPU composites were synthetically analyzed to reveal the effects of T-ZnOw and MoS2 on the friction excitation force and vibration reduction properties. The results showed that T-ZnOw enhanced anti-deformation property, and MoS2 weakened the friction excitation force in the friction process, which resulted in a lower coefficient of friction (COF) with a small amplitude, and eliminated the high-frequency vibration amplitude. In addition, the particle composition of 6% T-ZnOw and 9% MoS2 was controlled to obtain a low COF and the best vibration reduction properties. The knowledge obtained herein contributes to the understanding of the synergistic effects of T-ZnOw and MoS2 on COF and vibration reduction behaviors, and the development of a water-lubricated TPU composite stern tube bearing with low COF and good vibration reduction properties.

Preparation of polyethylene glycol brush grafted from the surface of nitrile butadiene rubber with excellent tribological performance under aqueous lubrication

The water-lubricated bearing will be in a state of poor lubrication when marine stern shafts operate under low speed and heavy load conditions, which could cause severe wear and vibration, endangering the stealth performance of underwater vehicles. In this study, the grafting of polyethylene glycol brush was carried out on the surface of nitrile butadiene rubber (PEG-g-sNBR) by “grafting from” method. Fourier-transform-infrared-spectroscopy, nuclear-magnetic-resonance, and scanning-electron- microscope results demonstrated that the PEG-g-sNBR brush was successfully synthesized, and the reactive site was found. Using a tribological test machine with a high-precision vibration acceleration sensor, the tribological behaviors of PEG-g-sNBR were studied under aqueous lubrication. The results showed that the coefficient of friction of PEG-g-sNBR was reduced by 73.4% at 100 rpm compared to pure NBR, its microscopic wear and vibrational energy were also lower than pure NBR. Moreover, the lubrication states were revealed by friction, wear, together with the complexity of friction-induced vibration signal time series, and a lubricating film was formed on the friction surface of PEG-g-sNBR at lower rotational speed. In addition, the PEG-g-sNBR could work stably for 12 h at 300 rpm, and still maintain good tribological performance.

Role of binder in controlling the noise and vibration performance of brake-pads

Although extensive research has been carried out for predicting and mitigating brake noise problems over the past decades, it is still challenging to predict its occurrence due to the complex nature of the brake system. Friction-induced vibration between the tribo couple (i.e. brake disk-pads) is one of the key players for increasing the noise and vibration issues in the brake system. The composition of friction materials (FMs) (i.e. pads/shoes) controls both tribological and noise-vibration (NV) performance. Binder (i.e. resin) is the heart of FMs which binds all the ingredients firmly and provides strength. A lot is reported on the types and amount of resin on the tribological performance, but no study addresses the noise and vibration performance adequately. This work investigates the role of binder in controlling the NV performance of the Cu-free brake-pads. Four types of copper-free brake-pads were developed with varying content (viz., 6, 8, 10, and 12 wt.%) of phenolic resin as a theme ingredient keeping the parent composition fixed. The natural frequencies and damping ratios for the developed pads were evaluated through experimental modal analysis of the pads. The detailed NV performance was evaluated on the in-house developed brake NV test rig by partly following the SAE J 2521 test schedule. Additionally, friction performance was also studied for different braking conditions. Results revealed that the compressibility, porosity, and damping ratio decreased, whereas hardness and natural frequency increased with the increase in resin content in the brake-pads. Overall, among all the pads, the brake-pad with 6 wt.% resin content proved best for the NV performance.

Analytical Scheme of Stability Analysis for 4-DoF Mechanical System Subjected to Friction-Induced Vibrations

Purpose:The stability problem for non-conservative multi-parameter dynamical system is usually associated with labor-intensive calculations, and numerical methods do not always allow one to obtain the desired information. The presence of circulatory forces often leads to the so-called ”destabilization effect” of the system under the influence of small dissipative forces. In this regard, it seems important to develop analytical approaches that make it possible to use a simplified scheme for checking the stability conditions.Methods:When obtaining and analyzing stability conditions, the algebra of polynomials and elements of mathematical analysis are applied. To obtain a simplified scheme for checking the stability conditions, an asymptotic method is used.Results and Conclusion:A mechanical system with four degrees of freedom which is under the action of dissipative, potential and non-conservative potential (circulatory) forces is considered. The stability problem of friction-induced vibrations is studying. In the case of weak damping an analytical approach is proposed that makes it possible to simplify the analysis of stability conditions, which, due to the presence of many uncertain parameters, are very cumbersome. With the help of numerical testing, the adequacy of the results obtained for the reduced conditions and full stability conditions was established. The results of the analysis make it possible to single out the ”advantageous” regions in the space of dimensionless parameters, which makes it possible to improve the design of the system to increase its reliability.

Tribological properties and lubrication state transitions of textured CSS-42L bushing filled with Sn-Ag-Cu-Ti3C2 of oil-film bearing

To improve the antifriction and vibration reduction performances of oil-film bearings in hydroelectric generating set, textured CSS-42L surfaces filled with Sn-Ag-Cu-Ti3C2 (TSs-SACT) were prepared, and the friction and vibration experiments under oil lubrication were carried out. The results showed that TSs-SACT with texture pitch of 600 μm and MXene of 5 wt.% (TSs-SACT(5%)-600) had the best antifriction, which reduced the fluctuation amplitudes of frictional forces and suppressed the friction-induced vibrations. The wear morphologies were improved by the synergistic effects of oil, grooves and Sn-Ag-Cu-Ti3C2, and TSs-SACT(5%)-600 with uniform profiles had the excellent wear resistance. The complexity of surface profiles could be characterized by fractal dimension, which can be enhanced by Sn-Ag-Cu-Ti3C2. TSs-SACT(5%)-600 with complex profiles keeps good antifriction during lubrication state transitions, which effectively improves the operation reliability of oil-film bearing in hydroelectric generating set.

Controlling mode-coupling instability in friction-induced vibration by acceleration feedback

Self-excited friction-induced oscillation, such as brake squeal, railway wheel squeal, chattering in machine tools, etc., is harmful in many mechanical systems. In the present study, the efficacy of acceleration feedback control with a second order filter is theoretically studied to mitigate friction-induced mode-coupling instability. Two different control strategies based on acceleration feedback are employed to control friction-induced mode-coupling instability of a two degrees-of-freedom linear system. Linear stability analysis near the equilibrium point of the system shows the efficacy of control laws to stabilize the system. The optimum filter parameters are determined by the pole crossover optimization method to attenuate the transient response as well as to achieve greater relative stability of the system. The Robustness study confirms the ability of the controller to stabilize the system in the presence of uncertainties in system parameters. Analytical results match closely with simulation results. Finally, nonlinearity in the form of stiffness is incorporated into the system for which the dynamics of the system show the presence of subcritical, supercritical Hopf bifurcation, and cyclic fold bifurcation. In the presence of nonlinearity, the feedback control is also able to reduce the range of instability of static equilibrium as well as the amplitude of the self-excited oscillation. The method of averaging is used to determine the stability and amplitude of the limit cycle. For the nonlinear system, the bifurcation diagram is constructed in AUTO and validated with results obtained from MATLAB SIMULINK and the method of averaging.

Tribological improvement of a high-speed train brake system and friction-induced vibration energy harvesting via a sandwich damping piezoelectric structure

A sandwich damping piezoelectric structure (SDPS) was designed to improve the wear and friction, reduce the friction-induced vibration and noise (FIVN) of high-speed train brake system, and convert friction-induced vibration (FIV) energy into electrical energy. Tribological tests were carried out to investigate the effect of the SDPS on the tribological behavior and the conversion efficiency of FIV energy into electrical energy. The results show that the proposed SDPS can convert FIV energy into electrical energy due to deformation, and the perforated structure produces greater deformation and a higher output voltage. The SDPS installed in the braking system improves the contact and wear behavior of the friction block, which reduces the FIV intensity, and can transform FIV energy into electrical energy.

전달경로분석법을 이용한 상용 전기 차량의 크립 그론 소음 저감 연구

Creep groan noise is a low-frequency, structure-borne noise that generally occurs when a vehicle starts moving from a standstill or comes to a gradual stop with minimal brake operation. It is generated by friction-induced vibrations from the stick-slip cycle of the brakes and are typically transmitted through the suspension. The investigations in this paper aim to reduce the creep groan noise by considering the frequency characteristics of the suspension. Transfer path analysis (TPA) is performed to identify the noise contribution of each suspension component. Thereafter, the cause of acoustic amplification and stick-slip cycle of creep groan are investigated through modal testing on the primary transfer path components. The noise level and trigger rate of creep groan noise are reduced by suppressing the behavior of the components using a dynamic vibration absorber (DVA). This shows the possibility of creep groan noise reduction from the perspective of the vehicle’s transfer system.

Nonlinear Energy Sink Inspired Design for Friction-Induced Vibration Suppression of Braking Systems

Abstract In this paper, a nonlinear energy sink (NES) is designed and applied for the suppression of the friction-induced vibration (FIV) of a braking system. The equation of motion of the braking system, as well as the NES, is established by using the Lagrange equation. The nonlinear restoring force of the NES is realized by vertically paralleling two linear springs. The friction force between the wheel and the braking block is calculated by the Coulomb–Stribeck friction model. The variation of the wheel speed with the friction force is derived by the kinetic energy theorem. From the simulation, two-stage FIV systems are observed. The wheel speed decreases monotonically in the first stage and oscillates around 0 m/s in the second stage. The effects of the contact pressure and stiffness coefficient of the block on the FIV system are analyzed. By series connecting the NES to the braking block, the amplitude of FIV braking system can be reduced significantly in the first stage. Furthermore, the effects of the mass ratio between the block and the NES, and the damping coefficient of the NES on the FIV braking system are also discussed. This research can be helpful for the vibration suppression design of the braking system in vehicles.

Tribological characteristics and mechanism of nitrile butadiene rubber coated with typical liquid lubricants

When marine stern shafts operate under low speed and heavy load conditions, the metal shaft and water-lubricated bearing will be in a state of boundary lubrication or even dry friction. Poor lubrication can cause severe wear and friction-induced vibration, endangering the stealth performance of underwater vehicles. In this study, several typical liquid lubricants, including liquid paraffin, tung oil (TO), dimethyl silicone oil (DSO), ionic liquid (IL), and hexamethylene diisocyanate (HDI) were selected as the surface coatings for nitrile butadiene rubber (NBR). Using a tribological test machine with a high-precision vibration acceleration sensor, as well as scanning electron microscopy (SEM) and other techniques, the tribological performance and mechanisms of the NBR samples coated with different lubricants were studied under various working conditions. The results showed that the liquid lubricant significantly reduced the coefficient of friction of the NBR at high rotational speeds by over 92.2%. The sample coated with HDI showed obvious tribochemical wear, and coating with the rest of the liquid lubricants decreased the specific wear rate of NBR. According to the friction-induced vibration signals, we found that an increase in loading aggravated friction-induced vibrations, and the vibrational energy was mainly concentrated in the low frequency range. The liquid paraffin and TO coatings barely changed the vibration characteristics of the NBR, while the other three lubricants produced more friction-induced self-oscillations. In conclusion, compared to the other liquid lubricants, TO exhibited the best tribological performance. The finding of this study further our understanding of the friction and vibration behaviours of polymer materials, providing a reliable basis for designing composite materials with good lubrication and vibration damping performance.