The design of any complex engineering system presents many challenges in terms of managing technical risks, customer requirements, commercial expectations and focusing minimised resources to achieve maximum results. A wide array of engineering design tools exist to administer management of engineering requirements, such as the Pugh Matrix and Failure Mode and Effect Analysis (FMEA), however these tools do not improve the understanding of the impacts of detailed design changes on customer requirements and product cost. Monte Carlo analysis is a design tool which can help fulfil this requirement, providing the ability to assess the effects of dimensional changes or component redesign on the end product performance and cost. It helps focus effort on design changes which improve measurable customer requirements while simultaneously reducing product cost. When engineering time and resources are limited it therefore enables a stronger focus on areas where maximum benefits can be achieved. This paper discusses the application of the Monte Carlo analysis design tool to the development of an improved adjuster mechanism for a commercial vehicle air disc brake and the lessons learnt in the process. The paper presents an explanation of the pad-to-rotor running clearance control for commercial vehicle disc brakes and provides an example based on the ELSA® air disc brake adjuster mechanism to describe how running clearance control can be improved, costs reduced and potential risks mitigated during the design process, along with initial physical test results to validate the design methodology. The Monte Carlo analysis tool provides a theoretical approach to understanding the effects of geometric and dimensional tolerance changes and manufacturing process capability on performance and cost prior to testing of initial samples, thereby providing greater confidence in the proposed solution at an earlier stage in the product development. The development process of the improved adjuster mechanism for the ELSA® air disc brake is not yet complete, but the use of Monte Carlo analysis has provided an insight into a new methodology for analysing engineering solutions that can be applied to a variety of future projects.

Malki, Refaat; Roberts, Paul; - Meritor Heavy Vehicle Braking Systems (UK) Ltd