A NEW METHOD IN THE IDENTIFICATION OF NOISE AND VIBRATION CHARACTERISTICS OF AUTOMOTIVE DISK BRAKES IN THE LOW FREQUENCY DOMAIN

Noise and vibration characterization is an important benchmark to reduce brake noise.Brake noise and vibration measurement is commonly done on an actual vehicle or on a brake dynamometer. A full scale brake dynamometer takes into account the attached mass which resembles the mass of a quarter scale vehicle. This paper proposes a testing method which eliminates the need for attached masses. This is achieved through the scaling of the brake system parameters to accommodate the loss of mass and produce similar conditions to those in actual braking. The measurement of noise and vibration is measured simultaneously and an FFT is performed to identify the frequencies of noise and vibration. An experimental modal analysis (EMA)is done to obtain the frequencies which the brake system tends to produce as a validation to the proposed method. It is shown that through this method the noise and vibration characteristics of the brake system and the unstable frequencies can be identified

A Parallel Study of Vibration Analysis and Acoustic Analysis in Low Frequency Brake Noise

An acoustic analysis in the investigation of brake noise shows the severity of the noise and its characteristics and a vibration analysis shows the excitation of noise that is present in the braking event. In this study, vibration and acoustic analyses were used to study the brake noise which is produced during braking. Vibration and acoustic data were collected simultaneously during braking to identify the braking condition. The data analysis focuses on the low frequency domain. The Fast Fourier method was used to analyse the vibration and acoustic signals. The computation of FFT was done independently and the frequency domains obtained were compared. The parallelism in the analysis was used to identify the acoustic source. The determination of the source will aid in brake noise reduction efforts and reinforce the vibration analysis method as a system identification method for brake noise

An Analytical Model to Identify Brake System Vibration within the Low Frequency Domain

This paper presents the analytical model of a brake system to investigate the low frequency vibration. The purpose of this study is to model and validate brake system vibration. The brake model was developed by applying the theory of sinusoidal traveling waves and wave super positioning. An experimental modal analysis (EMA) of the brake disc has been carried out to obtain the natural frequencies. Wave equations were then formulated based on the experimental data. These waves are super positioned to be shown as a single spatial and temporal function that will provide periodic excitation to the brake pad. The brake pad was modeled as a beam element with distributed friction force. The differential equations were solved using Green's dynamic formulation. The model is capable of predicting vibration behavior of the brake pad for whole range below 1 kHz which has shown strong agreement with the experimental results validated through in-house brake dynamometer. This brake model can serve as a tool to investigate the relationship between braking parameters and other variables within the brake system

Design and Modelling of Wave Energy Converter and Power Take-Off System

Ocean wave energy contains the largest energy density amongst all renewable energy. In Malaysia, the highest wave energy in the South China Sea is 12kW with maximum wave amplitude of 2 meters. This paper presents the design and modelling of wave energy converter and power take-off system that suitable for Malaysia in order to obtain the highest output of electrical power. A point absorber made up of a floating buoy connected by a fibre rope is used as wave energy converter. Linear permanent magnet generator has been used as the power-take-off system. This generator exploits directly the incoming sea wave vertical motion. This wave energy converter and power-take-off model have been developed and implement in Matlab. The model included wave energy, buoy water interaction, and linear generator. To extract highest wave energy, different parameters have been applied to the linear generator. Simulation results are presented showing three effects of three different parameters; winding coil turns, magnetic field strength and tooth width of the stator

High Speed Experimental Study of Friction Induced Vibration in Disc Brakes

Brake dynamic groan noise which is a low frequency phenomena associated with brake stop condition or slow brake release. This phenomenon said to be a friction-speed characteristic and commonly associated with low speed events. Thus a high speed test regarding this phenomenon is done. In conjunction with speed, pressure relation is also tested. Analysis of groan occurrence in relation of the speed and pressure is performed. The pressure relation to this event is expected to widen the study of this phenomenon which currently confined to stick and slip motions

Numerical prediction of brake friction pair vibration using dynamics green's function

The prediction capability of the brake system vibration is still unable to cover a broad range of frequencies. Current predictive models are contained within a particular range to cater for specific vibration types. Therefore, a numerical model which could make predictions in a broad spectrum range is required. The model presented in this paper is derived with such aim. The model is derived from the interaction between the friction pairs with the focus on the brake pad. The brake disc is simplified as a travelling sinusoidal wave. Where else, the brake pad is modelled as a Euler- Bernoulli beam with forces and distributed friction acting upon it. The Dynamic Green Equation applied in solving the derived friction pair equation. The outcome of the developed model predicted brake pad vibrational frequency coinciding accurately with brake dynamometer experimental results. Therefore, the validated model could be a viable prediction and study tool for various brake system parameters