Modeling requirements propagation to generate solutions for minimizing mass.

摘要

This thesis investigates the issue of weight reduction in moderately complex systems by addressing how to cascade the requirements to the individual components. Though mass can be reduced using different techniques such as material substitution or structural optimization; a systematic method for allocating mass as a function of requirements is necessary to provide novel alternate solutions that enable reduction of mass of the system while satisfying the requirements and tests governing them. Such a method can be developed by exploring different aspects of achieving weight reduction through change propagation in the parameters/elements governing the system. Though efforts have been made to relate the propagation of change in complex systems in terms of its impact on the system, current research has not yet developed a systematic method to generate novel solutions for mass reduction at the component level and assembly level by modeling the requirements propagation. The hypothesis to validate in this thesis is that a systematic method would facilitate generation of solutions at an assembly level of the system by eliminating non-functional requirements, merging functions or finding alternate working principles and their embodiment that satisfy the functionalities, requirements and tests imposed on that system. A case study is conducted on the BMW Z4 cooling system and it is observed that additional solutions are generated at a higher level of the hierarchy. Also, a visualization tool and accompanying algorithms to generate solutions at the component level using the multiple matrix method (a method developed by the research group as a part of the BMW project) has been developed to facilitate change propagation and traceability.