Temperature Gradients and Heat Stresses in Brake Drums 530234
The main purpose of this paper is to show that the phenomena classed under the generic thermal failure are not due to excessive temperature alone, but to a combination of high stresses and high temperature; other factors of importance are brake design, geometry, physical properties of brake lining, and those of the drum.
Concerning stresses, it will be shown that temperature gradients alone can cause them to reach well into the plastic state, even in a comparatively cool drum. Such heat stresses are known to give rise to crazing of the track, but in addition it is explained here that they are also responsible for heavy scoring, heat checks, or outright fracture.
A detailed analysis indicates why and how certain purely mechanical design aspects lower stresses and heat concentrations, thereby mitigating or even preventing the onset of thermal failure. Included is also an attempt to provide a rational basis for appraising the suitability of drum materials and of plating, in terms of simple physical properties.
Lastly, design charts and procedures are explained and illustrated in a few examples from the author’s practice.