An Introduction to Mechanical Engineering

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PREFACE:

This textbook will introduce you to the ever-emerging fi eld of mechanical engineering and help you appreciate how engineers design the hardware that builds and improves societies all around the world. 

As the title implies, this textbook is neither an encyclopedia nor a comprehensive treatment of the discipline. Such a task is impossible for a single textbook, and, regardless, our perspective is that the traditional four-year engineering curriculum is just one of many steps taken during a lifelong education.

 By reading this textbook, you will discover the “forest” of mechanical engineering by examining a few of its “trees,” and along the way you will be exposed to some interesting and practical elements of the profession called mechanical engineering.

This textbook is intended for students who are in the first or second years of a typical college or university program in mechanical engineering or a closely related field. Throughout the following chapters, we have attempted to balance the treatments of technical problem-solving skills, design, engineering analysis, and modern technology. The presentation begins with a narrative description of mechanical engineers, what they do, and the impact they can have (Chapter 1). Seven “elements” of mechanical engineering are emphasized subsequently in Chapter 2 (Mechanical Design), Chapter  3 (Professional Practice), Chapter 4 (Forces in Structures and Machines), Chapter 5 (Materials and Stresses), Chapter 6 (Fluids Engineering), Chapter 7 (Thermal and Energy Systems), and Chapter 8 (Motion and Power Transmission). Some of the applications that you will encounter along the way include sustainable urban infrastructures, virtual and rapid prototyping, nano machines, internal combustion engines, robotics, sports technology, magnetic resonance imaging, advanced materials, jet engines, micro-fluidic devices, automatic transmissions, and renewable energy. 

What should you be able to learn from this textbook? First and foremost, you will discover who mechanical engineers are, what they do, and what technical, social, and environmental challenges they solve with the technologies they create. Section 1.3 details a “top ten” list of the profession’s achievements. 

By looking at this list, you will recognize how the profession has contributed to your day-to-day life and society around the world in general. Second, you will find that engineering is a practical endeavor with the objective of designing things that work, that are costeffective to manufacture, that are safe to use, and that are responsible in terms of their environmental impact.

 Third, you will learn some of the calculations, estimates, and approximations that mechanical engineers can perform as they solve technical problems and communicate their results.

 To accomplish their jobs better and faster, mechanical engineers combine mathematics, science, computer-aided engineering tools, experience, and hands-on skills.

 You will not be an expert in mechanical engineering after having read this textbook, but that is not our intention, and it should not be yours. If our objective has been met, however, you will set in place a solid foundation of problem-solving, design, and analysis skills, and those just might form the basis for your own future contributions to the mechanical engineering profession. 

This textbook is intended for a course that provides an introduction to mechanical engineering during either the freshman or sophomore years. Over the past decade, many colleges and universities have taken a fresh look at their engineering curricula with the objective of positioning engineering content earlier in their programs. Particularly for the freshman year, the formats vary widely and can include seminars on “who are mechanical engineers” and “what do they do,” innovative design experiences, problemsolving skills, basic engineering analysis, and case studies. 

Courses at the sophomore level often emphasize design projects, exposure to computeraided engineering, principles of engineering science, and a healthy dose of mechanical engineering hardware. Core engineering-science courses (for example, strength of materials, thermodynamics, fluid mechanics, and dynamics) have evolved since the post– World War II era into their present, relatively mature, states. On the other hand, little if any standardization exists among introductory mechanical engineering courses. With limited discipline-specific instructional materials available for such courses, we believe that an important opportunity remains for attracting students, exciting them with a view of what to expect later in their program of study and in their future careers, and providing them with a foundation of sound engineering analysis, technical problem-solving, and design skills.

While developing the third edition of this textbook, our objective has been to provide a resource that others can draw upon when teaching introductory mechanical engineering to first-year and second-year students. We expect that most such courses would encompass the bulk of material presented in Chapter 1 (The Mechanical Engineering Profession), Chapter 2 (Mechanical Design), and Chapter 3 (Technical Problem Solving and Communication Skills). Based on the level and contact hours of their particular courses, instructors can select additional topics from Chapter 4 (Forces in Structures and Machines), Chapter 5 (Materials and Stresses), Chapter 6 (Fluids Engineering), Chapter 7 (Thermal and Energy Systems), and Chapter 8 (Motion and Power Transmission). For instance, Section 5.5 on materials selection is largely self-contained, and it provides an introductory-level student with an overview of the different classes of engineering materials. Similarly, the descriptions in Sections 7.6 through 7.8 of internal-combustion engines, electrical power plants, and jet engines are expository in nature, and that material can be incorporated in case studies to demonstrate the operation of some important mechanical engineering hardware. Rolling contact bearings, gears, and belt and chain drives are similarly discussed in Sections 4.6, 8.3, and 8.6. This textbook reflects our experiences and philosophy for introducing students to the vocabulary, skills, applications, and excitement of the mechanical engineering profession.

 Our writing has been motivated in part by teaching introductory mechanical engineering courses at our respective universities. Collectively, these courses have included lectures, computer-aided design and manufacturing projects, product dissection laboratories (an example of which is discussed in Section 2.1), and team design projects (examples of which are outlined in Sections 2.4 and 2.5 in the context of design conceptualization). 

A number of vignettes and case studies are also discussed to demonstrate for students the realism of what they are learning, including the “top ten” list of achievements developed by the American Society of Mechanical Engineers (Section 1.3), the fourteen “grand challenges” from the National Academy of Engineering (NAE) (Section 2.1), design innovation and patents (Section 2.2), urban power infrastructures (Section 2.5), integrated computer-aided engineering (Section 2.6), the loss of the Mars Climate Orbiterspacecraft and the refueling error on Air Canada Flight 143 (Section 3.1), the Deepwater Horizon oil spill disaster (Section 3.6), the Challenger disaster (Section 3.7), the Kansas City Hyatt Hotel disaster (Section 4.5), the design of Masdar City (Section 5.2), the design of advanced materials (Section 5.5), microfluidic devices (Section 6.2), blood fl ow in the human body (Section 6.5), sports technology (Sections 6.6 and 6.7), renewable energies (Section 7.5), internal combustion engines (Section 7.6), solar power generation (Section 7.7), and nanomachines (Section 8.3). The “Focus on . . . ” boxes in each chapter are used to highlight some of these interesting topics and other emerging concepts in mechanical engineering.



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