| Reducing design cycle time and cost, while improving quality, are important objectives in the design of new products. The premise of this work is that increased use of mathematical models in the design process will help satisfy these design objectives.; A methodology to improve the ability of engineers to use mathematical models, during the design process, is presented. The objective is twofold. The first objective is to deduce a proper system model, within the engineering context and specifications. The second objective is to have an analytical process by which the predicted system response can be altered, by perturbing the model parameters, to achieve certain performance specifications. The methodology is applicable to a complex system, considered to be comprised of several components. The methodology is divided into four processes.; The first two processes in the methodology are the formulation of component model templates and synthesis of system model templates. These processes are reviewed for components represented by second order differential equations. The third process is the deduction of proper system models. This two stage process incorporates previous work in the first stage, and extends the applicability to a more general class of problems. An accuracy criterion is used in the second stage to insure model accuracy. The fourth process extends the theory of large admissible perturbations to redesign of a complex system model. An example is presented to demonstrate the four processes that form the kernel of the methodology.; This work includes three further contributions. First, the applicability of the formulation, synthesis, and deduction processes are extended to include first order (state space) component models. Next, these three processes are developed in the bond graph modeling paradigm. Finally, component constraint modes are introduced in the methodology.; The result of this work is a methodology by which the proper model of a complex system is deduced, and these system models are redesigned. This methodology can be adopted early in the design cycle, thus enabling engineers to evaluate design alternatives quickly, before costly prototyping begins. This will shorten design cycle time and cost, while improving quality. |
