Abstract
Brake durability programmes are key activities during the development and validation of vehicle braking systems. These programmes are carried out on public roads, and help to deeply characterize the local driving patterns in each geographical area and show results of brake squeal noise, wear, braking energy and power. Relative to this topic, the automotive market in China is yearly growing up, and it is getting increasingly demanding and sensitive
to brake NVH issues. The objective of this study is to obtain a full characterization of the main brake durability patterns in this Chinese market and compare them with other main programmes worldwide.
This paper covers the most usual brake durability standards performed by the OEMs when developing and validating their vehicles braking system. Two different profiles appear in the comparison: city traffic and country road. Shanghai (China), Barcelona (Spain) and Los Angeles (USA) are used for the city traffic assessment; Yellow mountains (China) and Mojácar (Spain) are used for the country road evaluation. Each profile was conducted by local
drivers and characterized with the same vehicle model, brake parts specifications and keeping identical analysis criteria in order to obtain robust comparison outputs. The study includes a full objective parameterisation of each route and mileage accumulation, focussing on the driving profile description (brake applications, speed, deceleration ranges), squeal noise (frequency, loudness and occurrence) and parts wear (pad friction material
volume worn-out). New criteria of route severity, coming from a combination of the braking energy and power outputs of the brake applications performed are also introduced. All in all, the routes and fields of study are compared with reliable ratios that provide a complete understanding of the differences between the markets, taking as reference the Chinese patterns. In this way, it is also possible to anticipate which outputs would be obtained at other locations without performing them.
This paper enhances prior studies made in this field, increasing the number of durability programmes, but keeping exactly the same reliability and control of the conditions. Hence, the increase of the number of locations helps to enrich the comparison and results. In addition, the perspective of the study makes it possible to focus on the Chinese market, with one location for each profile.
The differences of each brake durability programme are clearly demonstrated in this study. Driving patterns, route severity, brake wear and NVH outputs are represented and compared, showing both divergences and similarities and helping to understand each market. The reference taken from the Chinese locations also puts the focus on a market which is in constant growth and that is expected to make great progress in this sector.
KEYWORDS Brake durability, comparison, severity, squeal, Chinese market