Budynas-Nisbett:Shigley's I.Basics 1.Introduction to T©The McGraw-Hill Mechanical Engineering Mechanical Engineering Companies,2008 Design,Eighth Edition Design Introduction to Mechanical Engineering Design Design is a communication-intensive activity in which both words and pictures are used,and written and oral forms are employed.Engineers have to communicate effec- tively and work with people of many disciplines.These are important skills,and an engineer's success depends on them. A designer's personal resources of creativeness,communicative ability,and problem- solving skill are intertwined with knowledge of technology and first principles. Engineering tools (such as mathematics,statistics,computers,graphics,and languages) are combined to produce a plan that,when carried out,produces a product that is fumnc- tional,safe,reliable,competitive,usable,manufacturable,and marketable,regardless of who builds it or who uses it. 1-2 Mechanical Engineering Design Mechanical engineers are associated with the production and processing of energy and with providing the means of production,the tools of transportation,and the techniques of automation.The skill and knowledge base are extensive.Among the disciplinary bases are mechanics of solids and fluids,mass and momentum transport,manufactur- ing processes,and electrical and information theory.Mechanical engineering design involves all the disciplines of mechanical engineering. Real problems resist compartmentalization.A simple journal bearing involves fluid flow,heat transfer,friction,energy transport,material selection,thermomechanical treatments,statistical descriptions,and so on.A building is environmentally controlled. The heating,ventilation,and air-conditioning considerations are sufficiently specialized that some speak of heating,ventilating,and air-conditioning design as if it is separate and distinct from mechanical engineering design.Similarly,internal-combustion engine design,turbomachinery design,and jet-engine design are sometimes considered dis- crete entities.Here,the leading string of words preceding the word design is merely a product descriptor.Similarly,there are phrases such as machine design,machine-element design,machine-component design,systems design,and fluid-power design.All of these phrases are somewhat more focused examples of mechanical engineering design. They all draw on the same bodies of knowledge,are similarly organized,and require similar skills. 1-3 Phases and Interactions of the Design Process What is the design process?How does it begin?Does the engineer simply sit down at a desk with a blank sheet of paper and jot down some ideas?What happens next?What factors influence or control the decisions that have to be made?Finally,how does the design process end? The complete design process,from start to finish,is often outlined as in Fig.1-1. The process begins with an identification of a need and a decision to do something about it.After many iterations,the process ends with the presentation of the plans for satisfying the need.Depending on the nature of the design task,several design phases may be repeated throughout the life of the product,from inception to termi- nation.In the next several subsections,we shall examine these steps in the design process in detail. Identification of need generally starts the design process.Recognition of the need and phrasing the need often constitute a highly creative act,because the need may be only a vague discontent,a feeling of uneasiness,or a sensing that something is not right. The need is often not evident at all;recognition is usually triggered by a particularBudynas−Nisbett: Shigley’s Mechanical Engineering Design, Eighth Edition I. Basics 1. Introduction to Mechanical Engineering Design © The McGraw−Hill 11 Companies, 2008 Introduction to Mechanical Engineering Design 5 Design is a communication-intensive activity in which both words and pictures are used, and written and oral forms are employed. Engineers have to communicate effec￾tively and work with people of many disciplines. These are important skills, and an engineer’s success depends on them. A designer’s personal resources of creativeness, communicative ability, and problem￾solving skill are intertwined with knowledge of technology and first principles. Engineering tools (such as mathematics, statistics, computers, graphics, and languages) are combined to produce a plan that, when carried out, produces a product that is func￾tional, safe, reliable, competitive, usable, manufacturable, and marketable, regardless of who builds it or who uses it. 1–2 Mechanical Engineering Design Mechanical engineers are associated with the production and processing of energy and with providing the means of production, the tools of transportation, and the techniques of automation. The skill and knowledge base are extensive. Among the disciplinary bases are mechanics of solids and fluids, mass and momentum transport, manufactur￾ing processes, and electrical and information theory. Mechanical engineering design involves all the disciplines of mechanical engineering. Real problems resist compartmentalization. A simple journal bearing involves fluid flow, heat transfer, friction, energy transport, material selection, thermomechanical treatments, statistical descriptions, and so on. A building is environmentally controlled. The heating, ventilation, and air-conditioning considerations are sufficiently specialized that some speak of heating, ventilating, and air-conditioning design as if it is separate and distinct from mechanical engineering design. Similarly, internal-combustion engine design, turbomachinery design, and jet-engine design are sometimes considered dis￾crete entities. Here, the leading string of words preceding the word design is merely a product descriptor. Similarly, there are phrases such as machine design, machine-element design, machine-component design, systems design, and fluid-power design. All of these phrases are somewhat more focused examples of mechanical engineering design. They all draw on the same bodies of knowledge, are similarly organized, and require similar skills. 1–3 Phases and Interactions of the Design Process What is the design process? How does it begin? Does the engineer simply sit down at a desk with a blank sheet of paper and jot down some ideas? What happens next? What factors influence or control the decisions that have to be made? Finally, how does the design process end? The complete design process, from start to finish, is often outlined as in Fig. 1–1. The process begins with an identification of a need and a decision to do something about it. After many iterations, the process ends with the presentation of the plans for satisfying the need. Depending on the nature of the design task, several design phases may be repeated throughout the life of the product, from inception to termi￾nation. In the next several subsections, we shall examine these steps in the design process in detail. Identification of need generally starts the design process. Recognition of the need and phrasing the need often constitute a highly creative act, because the need may be only a vague discontent, a feeling of uneasiness, or a sensing that something is not right. The need is often not evident at all; recognition is usually triggered by a particular