Modeling Articulated Brake Component Wear to Assist with Routing Decisions 2018-01-1890
Very few activities the brake engineer engages in can induce as much vexation as trying to find a satisfying routing for the flexible brake components such as hoses, wheel speed sensors, and electric parking brake cables. Ever increasing wheel end content, ever decreasing space, more complex suspensions, and bulkier (but lighter weight) suspension components provide quite the morass through which the components must be routed through. When routing is finalized - and free of any major issues - there frequently remains some combinations of articulation position and component tolerances that allow a light “friendly” touch between components (such as a sensor wire and a surface of a bracket or strut tube), or near misses where clearance exists but raises “what if” questions around what would happen if the tolerances would stack up slightly differently on another vehicle. These conditions are usually evaluated painstakingly by experienced engineers, and either corrected with design changes or accepted if deemed of extremely low risk - but these evaluations are generally subjective. The work presented in this paper introduces an objective assessment based on predicted wear of the component in a contact condition. It is intended to supplement - but not replace - the judgment of experienced and conscientious engineers. Data from customer usage measurements that describe the relative frequency of reaching various steering and suspension travel positions are combined with an energy-based wear model (in turn based on simple measurements of the contact condition) to generate a predicted wear volume. This wear volume is then translated through geometric calculations to a wear depth through the protective outer layer (such as hose outer cover or wire insulation), which can then ultimately be used to project the service life of the component before wear-through of the cover. The model is explained, and then demonstrated through a series of case studies.