International Journal of Vehicle Structures and Systems

Muhammad Haidir Hussin ¹, Abd Rahim Abu Bakar ¹, Mohd Rahimi Jamaluddin ¹, Romain Szlapka ²

Affiliations
1 Department of Automotive Engineering, Universiti Teknologi Malaysia, 81310 UTM Skudai, MY
2 Institut Superieur de l' Automobile et des Transports, 49, rue Mlle Bourgeois, F-58000 Nevers, FR

Abstract

This paper presents the effects of brake lining thickness due to wear on drum brake squeal. Brake lining will be worn out and subsequently its thickness will be reduced after a few number of braking applications. Hence dynamic properties of the lining, such as its natural frequency, might be changed. In this work, two different sets of brake lining, i.e., new and worn lining are used to investigate its effect on squeal generation. First, modal testing is performed to determine natural frequencies of those brake linings at free-free boundary condition. Later, squeal tests are carried out using brake dynamometer and squeal frequency is measured up to 10 kHz. Several squeal results are plotted over brake operating conditions to observe the influence of different lining thickness. In addition to these, squeal mechanisms, i.e., modal coupling due to closeness of the natural frequency between drum brake components and negative damping due to negative friction-velocity slope that contribute to the squeal generation are also investigated and discussed.

Keywords

Drum Brake, Squeal, Lining Thickness, Modal Testing, Squeal Mechanism.

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Abd Rahim Abu Bakar ¹

Affiliations
1 Vehicle Dynamic Research Group, Department of Automotive Engineering, Universiti Teknologi Malaysia, 81310 UTM Skudai, MW

Abstract

Noise, vibration and harshness (NVH) of motor vehicles has been an active research topic for so long not only due to increasing demand for better quality in vehicle design but also due to stringent noise pollution regulation imposed by the relevant authorities. As such vehicle manufacturers and component suppliers are facing a formidable challenge to tackle this NVH issue. When a vehicle and its components do not meet specified NVH targets and standards it could results in huge loss in the marketplace and more devastating it will also bring down together the brand image

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Saw Chun Lin ¹, Choong Chee Guan ¹, Abd Rahim Abu Bakar ², Mohd Rahimi Jamaluddin ², Wan Mohd Musyris Wan Harujan ², Badri Abd Ghani ²

Affiliations
1 Politeknik Premier Ungku Omar, Jalan Raja Musa Mahadi, 31400 Ipoh, Perak, MY
2 Automotive Engineering Department, Universiti Teknologi Malaysia, 81310 UTM Skudai, MY

Abstract

For decades, it has been a challenging task for brake engineers to reduce or totally eliminate squeal that emanates from brake systems. Despite the large number of proposals that have been implemented in tackling disc brake squeal, very few solutions are totally effective to reduce or suppress it. This paper presents an approach to tackle disc brake squeal through chamfered and slotted pad. A three-dimensional FE model of an actual disc brake system is developed. The baseline FE model is first simulated using complex eigenvalue and transient analysis to predict squeal and compared to the squeal tests data obtained in the brake dynamometer. A reasonable correlation is found between these results. Then, three different pad modifications are proposed, simulated and tested. It is shown that pad with chamfers and diagonal slot can totally suppress squeal both in prediction and squeal test.

Keywords

Disc Brake, Finite Element, Pad Modifications, Squeal, Complex Eigenvalue, Dynamic Transient, Brake Dynamometer.

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Muhammad Amir Zainudin ¹, Abd Rahim Abu Bakar ¹

Affiliations
1 Universiti Teknologi Malaysia, 81310 UTM Johor, MY

Abstract

Squealing from car disc brakes is a source of considerable discomfort and leads to customer dissatisfaction. The high frequency squeal noise above 1 kHz is very annoying and difficult to eliminate. Good braking performance against noise is considered to be a big market advantage. Reduction of brake squeal in the design stage is a formidable challenge that is faced by the automotive engineers. This paper attempts to provide a solution of eliminating disc brake squeal up to 10 kHz using a thin plate shim. First squeal occurrences in a disc brake assembly without thin plate shim are investigated for various operating conditions using a drag type brake dynamometer. Having identified the dominant squeal frequencies several shapes of thin plate shim are proposed and tested. The aim of using thin plate shims is to modify contact pressure distribution on the brake pads. A good shim should be able to effectively suppress and prevent those squeal frequencies generated in a disc brake system.

Keywords

Disc Brake, Squeal, Thin Plate Shim, Brake Dynamometer, Contact Pressure.

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