The conventional product development process employs a design–build–test philosophy. The sequentially executed product development process often results in a prolonged lead time and an elevated product cost. The e-Design paradigm presented in the Computer Aided Engineering Design series employs IT-enabled technology, including computer-aided design, engineering, and manufacturing (CAD/CAE/CAM) tools, as well as advanced prototyping technology to support product design from concept to detailed designs, and ultimately manufacturing. This e-Design approach employs virtual prototyping (VP) technology to support a cross-functional team in analyzing product performance, reliability, and manufacturing costs early in the product development stage and in conducting quantitative trade-offs for design decision making. Physical prototypes of the product design are then produced using rapid prototyping (RP) technique mainly for design verification. The e-Design approach holds potential for shortening the overall product development cycle, improving product quality, and reducing product cost. The Computer Aided Engineering Design series intends to provide readers with a comprehensive coverage of essential elements for understanding and practicing the e-Design paradigm in support of product design, including design method and process, and computer-based tools and technology. The book series consists of four modules: Product Design Modeling Using CAD/CAE, Product Performance Evaluation Using CAD/CAE, Product Manufacturing and Cost Estimating Using CAD/CAE, and Design Theory and Methods Using CAD/CAE. The Product Design Modeling Using CAD/CAE book discusses virtual mockup of the product that is first created in the CAD environment. The critical design parameterization that converts the product solid model into parametric representation, enabling the search for better designs, is an indispensable element of practicing the e-Design paradigm, especially in the detailed design stage. The second book, Product Performance Evaluation Using CAD/CAE, focuses on applying numerous computer-aided engineering (CAE) technologies and software tools to support evaluation of product performance, including structural analysis, fatigue and fracture, rigid body kinematics and dynamics, and failure probability prediction and reliability analysis. The third book, Product Manufacturing and Cost Estimating Using CAD/CAE, introduces computer-aided manufacturing (CAM) technology to support manufacturing simulations and process planning, RP technology and computer numerical control (CNC) machining for fast product prototyping, as well as manufacturing cost estimate that can be incorporated into product cost calculations. The product performance, reliability, and cost calculated can then be brought together to the cross-functional team for design trade-offs based on quantitative engineering data obtained from simulations. Design trade-off is one of the key topics included in the fourth book, Design Theory and Methods Using CAD/CAE. In addition to conventional design optimization methods, the fourth book discusses decision theory, utility theory, and decision-based design. Simple examples are included to help readers understand the fundamentals of concepts and methods introduced in this book series.

In addition to the discussion on design principles, methods, and processes, this book series offers detailed review on the commercial off-the-shelf software tools for the support of modeling, simulations, manufacturing, and product data management and data exchanges. Tutorial style lessons on using commercial software tools are provided together with project-based exercises. Two suites of engineering software are covered: they are Pro/ENGINEER-based, including Pro/MECHANICA Structure, Pro/ENGINEER Mechanism Design, and Pro/MFG; and SolidWorks-based, including SolidWorks Simulation, SolidWorks Motion, and CAMWorks. These tutorial lessons are designed to help readers gain hands-on experiences to practice the e-Design paradigm.

The book you are reading, Design Theory and Methods Using CAD/CAE, is the fourth (last) module of the Computer Aided Engineering Design series. The objective of the Design Theory and Methods book is to provide readers with fundamental understanding in product design theory and methods, and apply the theory and methods to support engineering design applications in the context of e-Design. In Chapter 1, a brief introduction to the e-Design paradigm and tool environment will be given. Following this introduction, important topics in design theory and methods, including decision methods and theory in engineering design, design optimization, structural design sensitivity analysis, as well as multi-objective design optimization will be discussed.

Chapter 2 focuses on decision making for engineering design, in which conventional decision methods and decision theory, as well as decision-based design developed recently are discussed. The conventional methods, such as decision tree and decision table, have been widely employed by industry in support of design decision making. On the other hand, decision theory offers scientific and theoretical basis for design decision making, which gained attentions of researchers in recent years. This chapter offers a short review on popular decision methods, design theory, as well as the application of the theory to support engineering design. This chapter serves as a prelude to chapters that follow.

Chapter 3 discusses design optimization, which is one of the mainstream methods in engineering design. We discuss linear and nonlinear programming and offer mathematical basis for design problem formulation and solutions. We include both gradient-based and non-gradient approaches for solving optimization problems. In this chapter, readers should see clearly the limitations of the non-gradient approaches in terms of the computational efforts of the design problems, especially, large-scale problems. The gradient-based approaches are more suitable to the typical problems in the context of e-Design. We focus on single-objective optimization that serves the basis to understand multiobjective optimization to be discussed in Chapter 5 that is much relevant to practical applications. We address issues involved in dealing with practical engineering design problems and discuss an interactive design approach, including design trade-off and what-if study, which is more suitable for support of large-scale design problems. We offer case studies to illustrate practical applications of the methods discussed and a brief review on software tools that are commercially available for support of various types of optimization problems.

Chapter 4 provides a brief discussion on the sensitivity analysis, that is, gradient calculations that are essential for design using the gradient-based methods. In this chapter, we narrow our focus on structural problems in hope to introduce basic concept and methods in gradient calculations. We include in this chapter popular topics, such as sizing, shape, and topology designs. We also offer case studies to illustrate practical applications of the methods discussed. Some aspect of the ideas and methods on gradient calculations for structural problems can be extended to support other engineering disciplines; for example, motion and machining time. Two case studies are presented to illustrate a practical scenario that involves integration of topology and shape optimization and an advanced topic that supports shape design for crack propagation at the atomistic level using multiscale simulations.

In Chapter 5, we introduce multiobjective design optimization concept and methods. We start with simple examples to illustrate the concept and introduce Pareto optimality. We then discuss major solution techniques categorized by the articulation of preferences. We also include multiobjective genetic algorithms that gain popularity in recent years. In addition, we revisit decision-based design using both utility theory and game theory introduced in Chapter 3. We make a few comments on the decision-based design approach from the context of multiobjective optimization. We include a discussion on software tools that offer readers knowledge on existing tools for adoption and further investigation. We also include two advanced topics, reliability-based design optimization and design optimization for product manufacturing cost.

In addition to theories and methods, two companion projects are included: Project S5 Design with SolidWorks and Project P5 Design with Pro/ENGINEER. These projects offer tutorial lessons that should help readers to learn and be able to use the respective software tools for support of practical design applications. We include two examples in each projects, design optimization of a cantilever beam, and multidisciplinary design optimization for a single-piston engine. Example files needed for going through the tutorial lessons are available for download at the book’s companion site. The goal of the projects is to help readers become confident and competent in using CAD/CAE/CAM and optimization tools for creating adequate product design model and adopt effective solution techniques in carrying out product design tasks.

This Design Theory and Methods book should serve well for a half semester (8 weeks) instruction in engineering colleges of general universities. Typically, a three-hour lecture and one-hour laboratory exercise per week are desired. This book (and the book series) aims at...