Introducing a Use Perspective in Product Design Theory and Methodology

In this paper it is argued that methods are needed for the design of a larger variety of product aspects than is feasible with mechanical engineering design methodology of today. Design methods found within the European schools of design are inadequate for the design of products other than machine systems of transforming character. The reason for this is that the underlying theories only describe the nature of ‘operand-transforming’ technical systems, and that the description of the process and function systems are too narrowly defined to be useful for the design of ‘non-transforming’ products, or for products where the human is involved as an active user. The paper takes as the standpoint that the functional language, in accordance with established foundation in engineering design theory, is a successful means to treat usability aspects of human-product systems. An extended process modeling view based on product life-phase thinking including a ‘use-process’ is presented, focusing the attention towards the use, and not merely the workings, of the product. Also, extended definitions of a number of concepts are proposed, and function-classes of the human-product system, leading to a more generally applicable use of functions as a modeling tool when describing products, is introduced. The proposed functional language is illustrated in a product case example.

Toward a Reasoning Framework of Design As Synthesis

Most of the previous research efforts for design process modeling had such assumptions as “design as problem solving,” “design as decision making,” and “design by analysis,” and did not explicitly address “design as synthesis.” These views lack notion and understanding about synthesis. Compared with analysis, synthesis is less understood and clarified. This paper discusses our fundamental view on synthesis and approach toward a reasoning framework of design as synthesis. To do so, we observe the designer’s activity and formalize knowledge operations in design processes. From the observation, we propose a hypothetical reasoning framework of design based on multiple model-based reasoning. We discuss the implementation strategy for the framework.

Constrained Shape Scaling of Trimmed NURBS Surfaces

A method to scale and deform a trimmed NURBS surface while holding the shape and size of specific features (trimming curves) unchanged is presented. The new surface is formed by scaling the given surface according to the scaling requirement first; and then attaching the (original) features to the scaled NURBS surface at appropriate locations. The attaching process requires several geometric operations and constrained free-form surface deformation. The resulting surface has the same features as the original surface and same boundary curves as the scaled surface while reflecting the shape and curvature distribution of the scaled surface. This is achieved by minimizing a shape-preserving objective function which covers all the factors in the deformation process such as bending, stretching and spring effects. The resulting surface maintains a NURBS representation and, hence, is compatible with most of the current data-exchange standards. Test results on several car parts with trimming curves are included. The, quality of the resulting surfaces is examined using the highlight line model.

Educational Interactive Multimedia Software: Can it Effectively Teach Engineering Concepts?

This paper provides a rigorous statistical analysis of the educational effectiveness of a curriculum module pertaining to direct current (DC) motors and motorized systems. Educational interactive multimedia software played an important role in the module, which also included lectures, a design project and other more traditional pedagogics. Pre- and post-tests were administered to measure learning during the module and individual test questions targeted specific areas of the curriculum to determine the contribution of the various resources to the entire learning environment. The data indicate that the module was indeed educationally successful and that the software contributed to the curriculum’s success. The module was particularly effective for promoting learning by female engineering students in the course and mitigated some discrepancies in prior knowledge. Students were also grouped into four preference groups based on analysis of students’ preference questionnaire responses. The data indicate that each preference group responded differently to the various teaching techniques employed in the curriculum.

Systems Engineering Design Projects in Freshmen Engineering Courses

The first year of most engineering programs: does not normally include much material in engineering practice or design, nor are professionalism, human factors or the concept of an engineering system solution to design problems emphasized. This lack of engineering content has been found to be a factor in the relatively high failure rate in the first year due to students not becoming interested in, and energized by, their studies. The author has developed a number of open-ended design problems which have been successful in teaching the engineering method to freshmen students while at the same time not over-taxing their relatively undeveloped engineering analysis skills. The projects are described and examples are available upon request from the author to allow interested readers to use them in their own programs. The other benefit of these projects has been in identifying students who have difficulty with written communications. Using the design project reports as a diagnostic tool we have been able to refer these students to assistance with their writing skills from the on-campus writing tutorial service.

The Relationships Between Data, Information and Knowledge Based on a Preliminary Study of Engineering Designers

The aerospace industry, along with other industries, has acknowledged the need to bridge the experience gap between novice and experienced designers [Moore, 1997]. The research aims to identify the support a novice designer requires to gain experience faster. The focus of this paper is to present some initial results of a study of novice and experienced designers. This initial study highlighted the difficulty in establishing consistent and precise usage for the terms data, information and knowledge. It is concluded that data, information and knowledge are relative concepts that cannot be defined in absolute terms. As relative concepts, these help differentiate experts and novices, and different types of novices. The relationships between data, information and knowledge are examined with the aim of prompting a discussion.

Comparison of Probabilistic and Possibility Theory-Based Methods for Design Against Catastrophic Failure Under Uncertainty

This paper compares probabilistic and possibility-based methods for design against catastrophic failure under uncertainty. It studies the effect of the amount of information on the effectiveness of each method. The study is confined to problems where the boundary between survival and failure is sharp. First, the paper examines the theoretical foundations of probability and possibility. It also compares the two methods when they are used to assess the risk of a system. Finally, it compares the two methods on two design problems. A major difference between probability and possibility is in the axioms about the union of events. Because of this difference, probability and possibility calculi are fundamentally different and one cannot simulate possibility calculus using probabilistic models. It is shown that possibility-based methods can be less conservative than probability-based methods in systems with many failure modes. On the other hand, possibility-based methods tend to be more conservative than probability-based methods in systems that fail only if many unfavorable events occur simultaneously. Probabilistic methods are better than possibility-based methods if sufficient information is available. However, the latter can be better if little information is available. A principal reason is that it is easier to identify the most conservative possibilistic model than the most conservative probabilistic model that is consistent with the available information.

Backward Mapping Methodology for Design Synthesis

Design efficiency and robustness at early stage of parametric engineering design play a critical role in reducing cycle time and improving product quality in the overall product development process. Usually, the “forward mapping” approach, is used to find designs, where the desirable performances are satisfied through large iterations of analysis and evaluation from design space to performance space. However, these approaches are time-consuming and involve blind search if the engineering system simulation models and/or initial conditions are not appropriately selected. On the other hand, common “reverse engineering” methods use domain-specific assumptions and are not effective in generic scenarios where the presumed conditions are violated. In this paper, a Backward Mapping Methodology for Design Synthesis (BMDS) is presented that can help conduct design synthesis rapidly and robustly at early stage of parametric engineering design. BMDS is a surrogate model-based approach that combines the strengths of metamodeling and statistics. It can help designers explicitly identify the robust design solutions that satisfy the designer-specified performance requirements through a “backward mapping” from the performance space directly to the design space. Preliminary case studies show its effectiveness and potential to be used as a generic early stage parametric design synthesis methodology in the future.

Supporting Product Introduction Processes Through Product Structures

This paper reports research on approaches for accessing and controlling product data within the Product Introduction Process (PIP) through the specification, prototyping, and integration of a set of product structures, product viewpoints and their relationships. A significant achievement has been the validation of a collection of computer-based models of product structures that enable the capture of work breakdown, product specification, product functionality, and the physical parts that comprise the product. Furthermore, a number of relationships between these product structures and the business processes that use and create them have been identified. The work presented in this paper demonstrates the importance of representing relationships between product introduction processes and products through the adoption of product structures. The potential for exploiting product structures to improve understanding of relationships between products and processes is illustrated. A case study captures flows of related functional and physical product structures within PIPs across a two-tier supply chain, and discusses the issues involved in supporting such related product and process information.

A Performance-Based Representation for Engineering Design

A performance-based representation is presented, which uses the Performance Orientation Chart (POC) to aid the designer throughout an interactive design process. Assuming that all performance attributes can be expressed as functions of the design parameters, three types of graphical matrix are shown in the POC: 1) The design form depicts the performance attributes varying with the correspondent design parameters; 2) The performance dependency addresses the trade-off information among the multiple specifications based on Pareto optimal solutions; 3) The parameter constraint space defines the feasible region of the design, parameters within the, active specification limits. Guided by these graphical matrices, the designer can interactively develop the design solution to satisfy multiple specifications. The methodology was applied to a practical design problem to explicate how the POC can help the designer acquire a satisfying design solution with extensive confidence. Finally, the discussion, indicates that the performance-based representation is significantly compatible with other current engineering design methodologies.