Brake Chamber Support Vibration Bench Test: Input Direction Influence 2017-36-0330
Vehicle components are frequently submitted to several vibratory conditions along their applications. At commercial vehicles industry, dynamic excited components are exposed to durability failures, which more than financial repairing costs, can potentially prevent value growth, since goods such as fuel, food, commodities, medicine, won’t reach their destinations and hold a whole economy chain.
Vibratory bench tests is a common resourced used by development companies (OEMs) to assess if component is properly design to fulfill vehicle operational conditions. It gathers the remarkable capability to fulfill at least three product development key pillars: minimize validation time, reduce financial expenditures (compared with traditional “on vehicle” tests) and reliable reproduction of mixed nominal conditions, not only considering track conditions of traditional validation track or factory surrounding but also capable to add vibration profiles of particular condition or from geographic distant region.
However, to accomplish a reliable assessment, dynamic test must be carefully specified. Not only in respect to input magnitude or frequency content but also with considered input degree of freedom.
In this paper, a reported field failure of truck’s brake chamber support is reproduced in an accelerated durability vibrational bench test. The relationship between the crack region with component’s natural frequency and its mode shapes is studied. Two input directions (vertical and lateral) were empirically and numerically tested and the respective results compared to the field failure. Even though vertical acceleration is significantly higher, the failure was only correlated when lateral input was considered, due to mode shapes sensibility to each input degree of freedom.