Design and engineering of carbon brakes

Abstract

The need for weight saving on Concorde stimulated the development of lightweight aircraft brakes. Carbon has long been recognized as a major constituent of brake friction materials and a carbon carbon composite has been engineered to provide adequate structural, thermal and friction characteristics for these disks. The use of carbon brake disks offered a 60 % weight saving compared with steel. Design of the composite is particular to the application. Orientation of the fibres on account of stress and heat flow requirements is vital to the achievement of a successful design. The material is considerably anisotropic and represents a compromise between strength and thermal properties, and manufacturing costs. Dunlop selected the chemical vapour deposition of carbon into a carbon fibre lay-up as the method of manufacture of the composite for Concorde brakes. The introduction of an incompletely developed process and a new composite brought novel problems to both design and manufacturing staff. Material property evaluation and extensive quality control practice played a major role.