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This research builds on previous work on function-based failure analysis and dimensional analysis to develop a design stage failure identification framework. The proposed framework is intended to provide an alternative approach to model the behavior for use in function-based failure analysis proposed in the literature. This paper specifically proposes to develop more detailed behavioral models derived from information available at the configuration level. The new behavioral model uses design variables, which are associated with units and quantities (i.e., mass, length, time, etc…), and generates a graph of interactions for each component to define the quantitative behavior of components. The dimensionless behavioral modeling is applied briefly to the analysis of functional failures and fault propagation at a highly abstract system concept level before any potentially high-cost design commitments are made. The main contributions in this paper include: a method to automatically select the main variables of interest, an automatic causal ordering of the variables based on their units, an automatically generated graph associating the variables, a machinery based on dimensional analysis allowing a quantitative simulation of the graphs, and a methodology to combine subgraphs and create component behavioral models.

The early stages of the design process are keys in the development of products and services. Nevertheless, they are marked by multiple constraints imposed on them, such as, most notably, a limited amount of time available for modelling and evaluating ideas and concepts. The present article develops an approach for modelling, and simulating initial design solutions during these critical early stages. The final objective is to minimize the amount of prerequisite knowledge a designer should have on the artefact being designed in order to propose, develop, and evaluate early models. First, the current work analyses the conditions necessary to develop a modelling and comparison environment for early design solutions. This is done through mathematical considerations of the design process. In a second part, the work proposes a modelling and simulation approach and develops the machinery behind it. The approach integrates and maps a series of normalized semantic descriptions of functions, generic engineering components and variables, a set of elementary laws associated with these components, and a set of elementary base units. All these elements are used to refine and guide the modelling process. This process is uses the Vaschy-Buckingham theorem followed by an approximation of the generic law describing the general behaviour of elementary components. This combination leads to an approximated model of the behaviour of the studied artefact. The model is further developed by implementing the behaviour in a system dynamics tool using two basic bricks of the system dynamics language, converters and flows. In a final part, the approach is illustrated through the case study of a beam structure.

During a system engineering process there are an important number of tasks that need to be organized, mapped together and recursively considered. The tasks that are mapped together are exchanging different flows of information and material. In this type of iterative processes, significant savings in term of development time can be made by providing a method that is optimizing the amount of feedbacks and iterations to the minimal level simply required for the successful development of the system. Task scheduling in a system engineering process can become extremely complex. Nevertheless it is a crucial step of the early stages of the systems engineering process for timeto-market, cost-efficiency and quality reasons. In this article, the authors are proposing to combine a computational approach (Discrete Differential Evolution) with Model Based Systems Engineering (MBSE) for minimizing iterations and reducing lead-time development. The present article is contributing to recent research works using Design Structure Matrixes (DSM) and computational methods for visualizing and analyzing systems engineering processes. The paper is proposing a framework integrating a model-based approach and a DSM based analysis of the process architecture to assist system engineers in organizing and scheduling tasks. As a result, this framework allows engineers to automatically populate DSMs generated from MBSE models developed in SysML. A specific stereotype is proposed to represent system development tasks in SysML. The sequencing of the engineering tasks is optimized with the application of a Discrete Differential Evolution algorithm (DDE) taking into account the different constraints. The practical use of the proposed framework is demonstrated on the case study of a mobile robot developed for the Eurobot competition. The article also discusses the possibility to use the current framework to analyze the impact of requirement changes on the scheduling of development tasks.

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