David C. Wynn

APPLIED SIGNPOSTING: A MODELING FRAMEWORK TO SUPPORT DESIGN PROCESS IMPROVEMENT

Companies which develop complex products are under constant pressure to produce better designs and to do so in less time, with lower cost and in more rational fashion than before. Achieving these goals often requires more than technical advancement; the processes by which products are developed must also be improved. Process improvement can be achieved in many ways, including the development of more robust plans, the introduction of better procedures and of new tools. In each case understanding the design process and its likely behavior is an essential prerequisite. When working with complex products this can pose a considerable challenge. In this paper we present a modeling framework which can support design process improvement activities ranging from process description to simulation and automation. The framework is implemented in the extensible software package ‘P3’, which has been applied to support process improvement projects in industry and academia. Four such studies in a UK aerospace company are discussed to illustrate the approach.

A MODEL-BASED APPROACH TO IMPROVE PLANNING PRACTICE IN COLLABORATIVE AEROSPACE DESIGN

The research reported in this paper complements previous work in the modeling and analysis of product development processes to reduce process risk and lead time. Such methods have found a receptive audience in industry, as evidenced by many academic case studies and the initiation of similar process improvement initiatives by the companies themselves. Given the ongoing ‘pull’ from a number of companies, we are interested to understand why such model-based methods have not yet impacted upon wider operational planning in industry. In this paper, based on an extended research study at a large UK aerospace company, we describe the application of the Signposting process modeling approach to the problem of developing a pragmatic method to support planning practice. The research described in the paper focuses on the elicitation, representation and manipulation of process information in a form which can inform planning and scheduling; during the study, addressing these issues was key to gaining support of the approach within the company.Copyright

Predicting Change Propagation in Complex Design Workflows

A simulation model to help manage change propagation through design workflows is introduced. The model predicts resource requirements and schedule risk of a change process, accounting for concurrency, multiple sources of change, and iterations during redesign. Visualizations provide insight to answer common management questions. The approach is illustrated using an aircraft design workflow from Airbus and a more complex turbine disk design workflow from Rolls–Royce.

Requirements-based development of an improved engineering change management method

Engineering changes (ECs) are essential in complex product development, and their management is a crucial discipline for engineering industries. Numerous methods have been developed to support EC management (ECM), of which the change prediction method (CPM) is one of the most established. This article contributes a requirements-based benchmarking approach to assess and improve existing methods. The CPM is selected to be improved. First, based on a comprehensive literature survey and insights from industrial case studies, a set of 25 requirements for change management methods are developed. Second, these requirements are used as benchmarking criteria to assess the CPM in comparison to seven other promising methods. Third, the best-in-class solutions for each requirement are investigated to draw improvement suggestions for the CPM. Finally, an enhanced ECM method which implements these improvements is presented.

Change prediction using interface data

Managing change can be challenging due to the high levels of interdependency in concurrent engineering processes. A key activity in engineering change management is propagation analysis, which can be supported using the change prediction method. In common with most other change prediction approaches, the change prediction method has three important limitations: L1: it depends on highly subjective input data; L2: it is capable of modelling ‘generalised cases’ only and cannot be; customised to assess specific changes; and L3: the input data are static, and thus, guidance does not reflect changes in the design. This article contributes to resolving these limitations by incorporating interface information into the change prediction method. The enhanced method is illustrated using an example based on a flight simulator.

Comparison of ilities for protection against uncertainty in system design

The concepts of reliability, robustness, adaptability, versatility, resilience and flexibility have been used to describe how a system design can mitigate the likely impact of uncertainties without removing their sources. With the increasing number of publications on designing systems to have such ilities, there is a need to clarify the relationships between the different ideas. This short article introduces a framework to compare these different ways in which a system can be insensitive to uncertainty, clarifying their meaning in the context of complex system design. We focus on relationships between the ilities listed above and do not discuss in detail methods to design-for-ilities.

System Architecture Modeling in a Software Tool Based on the Contact and Channel Approach (C&C-A)

The Contact and Channel Approach (C&C-A) has been developed to support the decomposition and design of technical systems. It is based on the principle that function and form emerge together during design, and therefore should be considered together in a design representation. This paper discusses the theory underlying the C&C-A, and describes its formalization and implementation in a software tool. The approach is applied to model the system architecture of a humanoid robot arm considering the impact of a proposed design change. This illustrates some of the main benefits of the Contact and Channel Approach: helping designers visualize, understand and communicate the complex dependencies between function and form in a system architecture.

A Computational Method to Support Product Architecture Design

The choice of product architecture can affect many factors, from the technical performance of a product to the design effort required, production costs, and satisfaction of lif ecycle requirements. This paper explores how computational tools can augment creative methods in product architecture de sign. It describes a method for synthesising product archite ctures in the form of networks of components. The set of architec tures for a product is specified using constraints on the struc ture of the network. The method has been implemented as a software tool, and an example illustrates how this might be used i n practice. Discussion of the example highlights some of the is sues which arise through using the method, particularly those of constructing an appropriate set of constraints, and of identifying promising architectures from the large set of synth esis results. Further work will address these issues and evaluate the approach in practice, to compare the cost-benefit r atio with more conventional methods for architecture design ( e.g. brainstorming).

Impacts of concurrency, iteration, design review, and problem complexity on design project lead time and error generation

A case study of an aircraft engine manufacturer is used to analyze the effects of management levers on the lead time and design errors generated in an iteration-intensive concurrent engineering process. The levers considered are amount of design-space exploration iteration, degree of process concurrency, and timing of design reviews. Simulation is used to show how the ideal combination of these levers can vary with changes in design problem complexity, which can increase, for instance, when novel technology is incorporated in a design. Results confirm that it is important to consider multiple iteration-influencing factors and their interdependencies to understand concurrent processes, because the factors can interact with confounding effects. The article also demonstrates a new approach to derive a system dynamics model from a process task network. The new approach could be applied to analyze other concurrent engineering scenarios.

Redesigning the design process through interactive simulation: a case study of life-cycle engineering in jet engine conceptual design

Many aerospace companies are currently making the transition to providing fully-integrated product-service offerings in which their products are designed from the outset with life-cycle considerations in mind. Based on a case study at Rolls-Royce, Civil Aerospace, this paper demonstrates how an interactive approach to process simulation can be used to support the redesign of existing design processes in order to incorporate life-cycle engineering (LCE) considerations. The case study provides insights into the problems of redesigning the conceptual stages of a complex, concurrent engineering design process and the practical value of process simulation as a tool to support the specification of process changes in the context of engineering design. The paper also illustrates how development of a simulation model can provide significant benefit to companies through the understanding of process behaviour that is gained through validating the behaviour of the model using different design and iteration scenarios.