Prediction of Disc Brake Contact Pressure Distributions by Finite Element Analysis

Abstract

Pada masa kini, penentuan taburan tekanan sentuhan dianggap penting dalam kajian terhadap hingar squeal bagi sistem brek cakera. Ini kerana analisis sentuhan merupakan sebahagian daripada prosedur dalam penggunaan kaedah nilai–eigen komplek. Kaedah ini memerlukan matrik kekakuan yang tidak simetri di mana ia diperolehi hasil daripada kekakuan sentuhan dan juga pekali geseran pada permukaan cakera dan pelapik brek. Kertas keria ini menganalisis taburan tekanan sentuhan pada permukaan brek cakera dan pelapik brek menggunakan model terperinci 3 dimensi yang dibina. Bagi tujuan tersebut, satu program komputer komersial digunakan secara meluas. Kajian ke atas tekanan sentuhan terhadap beberapa kategori model unsur terhingga dilakukan. Model yang memberi hasil keputusan yang praktikal akan dipilih untuk kajian seterusoya. Akhir sekali, beberapa model yang diubahsuai bentuk/struktur dan bahan disimulasikan bagi mendapatkan taburan tekanan sentuhan yang lebih sekata. Ini penting bagi sistem brek kerana taburan yang sekata boleh mengelakkan kehausan pada bahagian tertentu dan seterusnya memanjangkan jangka hayat pelapik brek. Kata kunci: Kaedah unsur terhingga, brek cakera, kaedah nilai-eigen, taburan tekanan sentuhan, kehausan In recent years, prediction of contact pressure distributions is regarded as an important step in studying disc brake squeal noise. Contact analysis forms part of the whole procedure in the complex eigenvalue method. The essence of such a method lies in the asymmetric stiffness matrix derived from the contact stiffness and the friction coefficient at the disc/pads interfaces. This paper presents the analysis of the contact pressure distributions at the disc/pad interfaces using a detailed 3–dimensional finite element model of a real car disc brake. A general–purpose commercial software package was utilised and assessed. The paper also investigates different levels in modeling a disc brake and simulating contact pressure distributions. Having obtained the suitable model, prediction of interface pressure distributions on an original disc brake was carried out. Finally, modifications on the geometry and/or materials of disc brake components were performed to search for a more uniform contact pressure distribution. It is believed that a uniform contact pressure distribution could prevent excessive tapered wear on the pads and subsequently could prolong the life of pads. Key words: Finite element method, disc brake, eigenvalues method, contact pressure distribution, wear