Squeal Noise Research Articles

Squeal Noise Analysis Using A Combination of Nonlinear Friction Contact Model

Squeal noise is generated by an unstable friction-induced vibration in a mechanical structure with friction load. Nonlinear mechanisms like sprag-slip, stick-slip, and negative frictions damping are believed in contributing to generate this kind of noise. However, the prediction of its occurrence still counts on the analysis of complex-linear eigenvalue, which may underpredict the number of unstable vibration modes. The structure also is found to seem to generate squeal noise randomly. In this paper, nonlinear analysis of a squeal noise is investigated. The study is conducted numerically by a simple two-degree of freedom model and an experimental observation using a circular and slider plate with a friction contact interface. The friction force is modeled as a function cubic nonlinear contact stiffness and nonlinear negative velocity function of friction coefficient. It is found that mode coupling instability will occur if the normal contact stiffness and friction coefficient exceed the bifurcation point to generate a couple-complex conjugate eigenvalue and eigenvector. However, when the system is stated linearly stable, instability still can appear because of increasing the nonlinear contact stiffness and coefficient of friction. The instability is affected significantly by relative velocity and pressing force. Both parameters dynamically change depending on the vibration response of the structure. Furthermore, it is also found the stick-slip phenomenon interacted with mode coupling instability to generate squeal noise. It contributes to supply energy to increase the response caused by instability of mode coupling.

Brake Squeal Analysis using Finite Element Analysis Method

The Finite Element Analysis (FEA) is widely used for solving many Engineering problems. This paper focuses on use of FEA for Brake Squeal Analysis. Automobiles generates several kinds of noises like Groan, chatter, judder, moan, and squeal. Brake squeal can be defined as an unwanted noise that occurs due to dynamic instability of the system. It generally occurs in the frequency range of 1 KHz to 16 KHz.The aim of the project is to predict the squeal noise occurring at particular frequencies at an early stage of development using full corner brake model. The preprocessing of the full corner brake model is done using Hypermesh while the processing and post-processing is to be carried out by using Abaqus. Analysis uses non-linear static simulation which is followed by Complex Eigen Value (CEA) extraction for carrying out the squeal Simulation. It provides the relation between damping ratio and frequency (Real part of the complex Eigen value). If the damping ratio at any particular frequency is above one, it can be said that squeal will occur at that particular frequency.

Piezoelectric-based dither control for automobile brake squeal suppression under various braking conditions

Automobile brake squeal noise, which is nonlinear, friction-induced vibration in the frequency range 1–16 kHz, still remains a major problem for the automotive industry. This article presents analytical and experimental investigations into the application of dither control for active suppression of automobile disc brake squeal. Dither is a concept of active control that introduces high-frequency actuation into a system to suppress a much lower frequency disturbance. In this study, a specially designed brake system is built, in which a piezoelectric stack actuator in the piston of a floating caliper brake applies the dither input. In the experiments, squeal noise generated under the drag mode and various dynamic modes are considered. The results indicate that this piezoelectric-based dither control could effectively suppress the brake squeal noise by 5–10 dB and the squeal occurrence by up to 60% under various braking conditions.

Study on analytical model for curve squeal noise with coupled vibration between wheel and rail

Study on analytical model for curve squeal noise with coupled vibration between wheel and rail

Characteristics of Magneto-Rheological Elastomer under Stick-Slip Condition

This paper examines the characteristics of stick-slip phenomena between the glass plate and Magneto-Rheological Elastomer (MRE) surface. Stick-slip phenomena are the spontaneous jerking motion that occurs while two objects are sliding over each other, usually accompanied by noise. Stick-slip is generated when it involves discontinuous frictional degradation when moving from static friction to dynamic friction. The phenomena can lead to uneven wear patterns, vibration and squeal noise which cause a shorter lifespan for the corresponding mechanical elements. MREs are kind of function materials to consist of a polymeric matrix with embedded ferromagnetic particles. Mechanical properties of the MREs can be controlled by the application of magnetic fields. The magnetic field-based controllability can be applied to the control of stick-slip phenomena. The friction experiment is conducted with the Reciprocating Friction Tester (RFT). The sliding speed of the RFT should be in low-speed conditions in order to make the stick-slips relatively easy to occur. A uniform magnetic field and a weight load are applied to the MRE sample to observe the effect of various experimental parameters on the movement of the stick-slip. In addition, frictional sounds due to the stick-slip phenomenon under different loads and magnetic field strength are measured and analyzed. The results of this experiment show that as the strength of the magnetic field increases, the difference in stiffness between the wipers-glass decreases, mitigating fricatives. The result is expected to be well applied to low-noise automotive wipers based on the controllability of friction behavior and squeal noise.

Numerical investigation of material properties and operating parameters effects in generating motorcycle break squeal using the finite element method

One of the factors of influence on driver comfort is undoubtedly the noise. The noise generated by the brake, in addition to causing discomfort, can cause uncertainty as to the existence of mechanical failure in the brake system. Among the types of noise related to disc brakes, what has been generating a greater interest of researchers is squeal noise. This research paper is concerned with the disc brake squeal problem for motorcycles. The aim of the present research is developing a finite element model of the motorcycle disc brake in order to improve the understanding of the influence of material and operational parameters on squeal generation. Stability analysis of the disc brake assembly was accomplished to find unstable frequencies. A parametric study was carried out to investigate the effect of changing Young’s modulus of the disc, back plate, friction material and operational parameters, as rotational velocity of the disc, pressure and temperature, on squeal generation. The results of simulation indicated that material and operational parameters play a substantial role in generating the squeal noise.

Transient vibro-acoustic analysis of squeal events based on the experimental bench FIVE@ECL

The proposed study investigates the transient and stationary non-linear vibrations and acoustic phenomena occurring during the squeal phenomenon. Experiments are performed on the test bench Friction-Induced Vibration and noisE at Ecole Centrale de Lyon (FIVE@ECL).The first major contribution of the study is to demonstrate the ability of this test bench to reproduce transient squeal events for a given operational condition, allowing to conduct a thorough and robust study on the physical understanding of transient vibration and acoustic squeal events. The second main contribution is to discuss the potential links between the emergence of vibrations on the two pads, the disc and the caliper, and the squeal noise in near-field and far-field.

Shape optimization of a disc-pad system under squeal noise criteria

This paper deals with the parametric shape optimization of a simplified model of brake system under squeal noise criteria. As brake squeal phenomenon induces under-quality perception for industrial structures such as cars and trains, its understanding and management are important challenges for future systems design. Hence, we expose an optimization methodology based on meta-model for a proposed computationally expensive stability criteria representing the squeal noise. Sensitivity analysis is first conducted to assess and validate the chosen geometrical parameters. Then, a Pareto front is obtained through optimization of the system, leading to a set of optimal solutions for theconsidered multi-objective case.

실차 적용을 고려한 브레이크 스퀼 소음 저감 고주파 디더 제어 시스템 개발 및 실험적 검증

실차 적용을 고려한 브레이크 스퀼 소음 저감 고주파 디더 제어 시스템 개발 및 실험적 검증

Tribology performance, airborne particle emissions and brake squeal noise of copper-free friction materials

Copper and its alloy have been widely used in the formulation of non-asbestos organic (NAO) friction materials as reinforcements and/or additives. But U.S.A has raised a legislation to reduce the copper content in friction materials due to the toxicity of copper in wear debris. Thus, there is a need to develop copper-free friction materials which also owns the desired tribology performance. In the present study, two new copper-free non-asbestos organic (NAO) friction materials were developed by replacing the copper fiber with steel fiber (named SFM) or ceramic fiber (named CFM). Friction and wear behaviors, airborne wear particle emissions and brake squeal noise of these two copper-free friction materials were evaluated and compared with a reference copper containing friction material (RFM) by using a pin-on-disc test rig. Results show that all friction materials have comparable friction coefficients, and the specific wear rates of SFM and CFM are larger than that of RFM. The mean fractal dimension of RFM surface is larger than those of SFM and CFM surfaces. For the airborne particle emissions, RFM presents the lowest particle number emissions and particle mass concentrations (PMCs) of PM10 (particles smaller than 10 μm) and SFM presents the highest values of these two results. For brake squeal noise, the brake squeal noise of all friction materials has comparable A-weighted sound pressure levels (SPLs). It can be concluded that the replacement of copper fiber with steel and ceramic fibers can obtain comparable tribology performance and brake squeal noise, but it will increase the particle emissions.

Drum brake noise reduction

The reduction in drum brake squeal noise which greatly affects rider comfort as well as surrounding noise level has become a more challenging and trending problem in two-wheeler industries. In this paper, squeal noise is reduced by means of liner modification with different width and depth of the liner slot. Effect of change in liner geometry on squeal noise reduction is studied analytically and verified experimentally. A full nonlinear perturbed modal analysis is used to find the stability of the system. In order to validate the analytical results, experimental tests are carried at a certain slow speed having low brake pedal force. The experimental results show that the drum brake squeal noise is found to be reduced by a significant amount by applying the proposed method. It is found that significant modification in geometry of liner in view of noise reduction is not affecting much the vehicle performance.

Evaluation of curve squeal noise with wheel-like rolling disc

Evaluation of curve squeal noise with wheel-like rolling disc

Prediction of wheel squeal noise under mode coupling

Wheel squeal vibration and noise amplitude under the effects of mode coupling and rising and falling creep behavior is investigated and predicted using an efficient analytical model. Based on previous research, a simplified modal dynamics model for wheel squeal noise amplitude is enhanced to include two coupled modes. Closed form analytical solutions for the vibration and squeal noise amplitude are determined under combined squeal mechanisms of full sliding falling friction and mode coupling. The analytical predictions are then compared with numerical time domain simulations of squeal vibrations with nonlinear creep and sound pressure level amplitude over a range of angle of attacks and contact angles for the inner and outer wheels in a curve. As an example, the effect of rail dynamics on squeal amplitude is quantified by comparing results with and without the mode coupling and the conditions and occurrences of stiffness and viscous mode coupling (where the stability is determined by the coupled structural complex stiffness, due to the closeness of the uncoupled modes, and damping, respectively) are clearly identified and quantified. The viscous mode coupling from the rail is shown to significantly reduce and/or eliminate conventional wheel squeal, for the inner and outer wheels, at higher contact angles defined by the friction coefficient. It can otherwise amplify (up to approximately 5 dB) or cause squeal, under high rail damping for the leading outer wheel. Conversely, it is shown that under only a small range of contact angles and closely matched uncoupled modes, stiffness mode coupling causes very high amplitude squeal beyond the scope of the simplified creep model. Rail mass and damping only models are shown to represent the occurrences of stiffness and viscous mode coupling, respectively, where the optimum amplitudes are dependent upon the complex stiffness and rail damping, respectively. The scope of the efficient analytical model is quantified and shown to be limited by excessive non-proportional damping and very high squeal amplitudes associated with reverse full sliding. The analytical model is shown to provide insight into the effects of mode coupling dynamics on wheel squeal noise amplitude and possibly help explain the enigma that squeal occurs seemingly unreliably in the field.

Wheel squeal noise control under water-based friction modifiers based on instantaneous rolling contact mechanics

Friction modifiers have been shown to be effective in reducing wheel squeal noise but not reliable in eliminating the phenomenon. To investigate this, wheel squeal noise under water-based friction modifiers is predicted using a mathematical model taking into account assumed instantaneous traction-creep behaviour. The instantaneous lateral creep curves are determined from quasistatic measurements under water-based friction modified conditions and used to obtain analytical predictions of wheel squeal noise levels that are verified numerically and experimentally based on a two disk testrig. Similar levels of squeal are obtained in both dry and water-based friction modified conditions at higher speeds despite the measured lateral creep curve not showing ‘falling friction’. For low speed, the water-based friction modification is shown to be successful in eliminating squeal except for very high angles of attack where noise levels are still greatly reduced. Subsequently, the efficient modelling is used to identify what modifications to the creep curve provide the best squeal noise reduction and elimination capabilities.

Influence of structural modifications of automotive brake systems for squeal events with kriging meta-modelling method

Squeal noise is an important issue in the automotive industry since it is one of the main reasons for the return of vehicles to the customer service. Hence, it is essential to predict it in the design stage of a brake system. The Complex Eigenvalue Analysis (CEA) remains the most widely used method to predict squeal noise in the automotive industry. The numerical cost associated to this method is important enough to make impossible the use of parametric studies. The present study proposes the use of the kriging method to surrogate the eigenvalues computed by the CEA by taking into consideration different uncertain parameters, namely the friction coefficient and two small masses added to the caliper that correspond to a classical choice of structural modifications used in the final phase of a brake design to avoid squeal noise. Thus, it is possible to assess the influence of the structural modifications on the stability of the brake system and to get information to choose the best brake design. Finally, uncertainty propagation is performed to get a robust design of the brake.

Ultrasonic Evaluation of Young’s Modulus for Reduction of Brake Squeal Noise

Elastic properties of friction materials in brake linings are important design parameters because modulus variations may lead to noise generation of braking systems. This paper is to describe about ultrasonic estimation of Young’s modulus of brake linings concerned with squeal noise problem for commercial trucks. Phase velocity of ultrasound propagating through brake lining was measured to calculate Young’s modulus based on elastic relations of acoustic waves with material properties. Two kinds of brake lining samples were produced with the same composition by different manufacturing process, one of which is a traditional product and the other is an advanced one developed for brake noise reduction. Five rectangular samples were cut out from each type of brake linings and machined for ultrasonic test. Acoustic pulse of 500KHz was applied to each sample to calculate the time-of-flight(TOF) for the measurement of wave velocity and Young’s modulus. The results of ultrasonic test indicate that the low noise brake samples have a less deviation of Young’s modulus than the traditional brake samples. This agrees with previous researches and FEM analysis that Young’s modulus variation of brake linings affects the squeal propensity and the instability of brake system.

A new approach considering the brake pad geometry in brake squeal

Friction-induced vibration can be defined as a type of dynamic instability problem. Generally, engineers and researchers working in the field of noisy disc brakes treat instabilities due to a friction force as self-excited vibrations. The most known case is squealing. For disc brake mechanisms, mode coupling is responsible for generating annoying squeal noise and vibration in brakes. In order to identify whether a system is stable or not, a complex eigenvalue analysis is achieved. In this paper, a new dynamic model of disc brake squeal was developed. The analytical formulation of the dynamic equation of motion was detailed. Moreover, a stability analysis of disc brake vibrations including gyroscopic effect, negative friction slope and mode coupling with non-proportional damping was developed. Then, the disc brake parameters optimization was discussed by studying the influence of the angular velocity, stiffness and damping coefficient of the pad and friction coefficient and, especially, the pad geometry (opening angle). The improved model led to a better understanding of the unwanted squeal phenomenon and to designs targeting their avoidance.

Investigation of friction-induced vibration in a disk brake model, including mode-coupling and gyroscopic mechanisms

The brake squeal reduction has been extensively investigated in many academic and industrial researchers. Friction-induced vibrations can be considered as a dynamic instability problem. Generally, automotive engineers and researchers working in the domain of disk brake noise treat instabilities due to the force of friction as a friction-induced vibration. In the case of squeal noise, mode coupling may cause instability of the system. The aim of this article is to propose a minimal two degree of freedom disk brake model in order to investigate the effects of different parameters on mode-coupling instability. This model takes into account self-excited vibration, gyroscopic effect, friction-induced damping, and brake pad geometry. Thus, a stability analysis of equilibrium by calculating complex eigenvalues is presented to investigate the influence of the main parameters on the stability zone such as the opening angle of the brake pad and preload. For the validation of the stability analysis, squeal index and time domain response are used. The results obtained show the importance of optimizing the physical and geometrical parameters of the brake and that some of these parameters have greater effects compared to the others to reduce noise.

A Study on Micro-Perforated Panel Absorber with Multi-Layered and Parallel-Arranged Structure to Enhance Sound Absorption Performance

Micro-perforated panel absorber (MPPA) can be manufactured using various materials and can be applied to various fields. There are restrictions on applying MPPA because of the narrow sound absorption bandwidth. To solve this problem, the design parameters are controlled or the MPPA is constructed in parallel or multilayer structures. However, It is not easy to make holes of diameter of 0.1 mm or less in a general method. If there are constraint conditions, MPPA may not be designed for the target frequency band. We propose MPPA combined with multi-layer structure and parallel arrangement to effectively enhance the sound absorption performance. A calculation method for the absorption coefficient of the proposed MPPA is derived and the validity of calculation results is confirmed through the experiments. The sound absorption characteristics according to change of design parameters and structural change are analyzed and the following results are obtained. First, MPP with one kind of hole and various cavity depths is more effective in enhancing the sound absorption performance than MPP with various types of holes and one type of cavity depth. Second, in double-layer MPPA, it is confirmed again that the absorption performance is improved when the hole diameter and porosity of the MPP from the source are higher than those of the MPP from a rigid wall. Third, when MPPA with multi-layer structure and parallel arrangement is designed, both MPP properties and cavity depths should be considered to achieve good performance of MPPA. Based on the results, we design the prototype MPPA. Result of reverberation room test shows that prototype has a good sound absorption performance. We will improve the prototype MPPA and conduct a field test to reduce railway noise such as squeal noise.

Application of dithering control for the railway wheel squealing noise mitigation

A new methodology for mitigation of the wheel squealing is proposed and investigated based on the dithering control. The idea can be applied in railway lines particularly in urban areas. The idea is clearly presented, and applied to a validated model. A full-scale model including the vehicle, curved track and wheel/rail contact is developed in the time domain to analyze the possibility and level of wheel squeal noise. Comparing the numerical results with a field test, the model is validated in different levels namely i) occurrence, ii) squealing frequency and iii) noise level. Two different approaches are proposed a) dithering of the wheel with piezoelectric patches and b) dithering of the rail with piezoelectric stacks. The noise level as well as the wheel responses is compared after applying the control strategy. A parametric study is carried out and effect of the dithering voltage and frequency on the squealing noise is investigated. It is found that both the strategies perform quite effectively within the saturating threshold of piezoelectric actuators.