《Design and manufacturing（ME371、ME337）》课程教学资源（参考教材）《Shigley’s Mechanical Engineering Design》（Richard G. Budynas、J. Keith Nisbett，Ninth Edition）

6 Mechanical Engineering Design Figure 1-1 Identification of need The phases in design, acknowledging the many feedbacks and iterations. Definition of problem Synthesis Analysis and optimization Evaluation Iteration Presentation circumstance or a set of random circumstances that arises almost simultaneously.For example,the need to do something about a food-packaging machine may be indicated by the noise level,by a variation in package weight,and by slight but perceptible vari- ations in the quality of the packaging or wrap. There is a distinct difference between the statement of the need and the definition of the problem.The definition of problem is more specific and must include all the spec- ifications for the object that is to be designed.The specifications are the input and out- put quantities,the characteristics and dimensions of the space the object must occupy, and all the limitations on these quantities.We can regard the object to be designed as something in a black box.In this case we must specify the inputs and outputs of the box, together with their characteristics and limitations.The specifications define the cost,the number to be manufactured,the expected life,the range,the operating temperature,and the reliability.Specified characteristics can include the speeds,feeds,temperature lim- itations,maximum range,expected variations in the variables,dimensional and weight limitations,etc There are many implied specifications that result either from the designer's par- ticular environment or from the nature of the problem itself.The manufacturing processes that are available,together with the facilities of a certain plant,constitute restrictions on a designer's freedom,and hence are a part of the implied specifica- tions.It may be that a small plant,for instance,does not own cold-working machin- ery.Knowing this,the designer might select other metal-processing methods that can be performed in the plant.The labor skills available and the competitive situa- tion also constitute implied constraints.Anything that limits the designer's freedom of choice is a constraint.Many materials and sizes are listed in supplier's catalogs, for instance,but these are not all easily available and shortages frequently occur. Furthermore,inventory economics requires that a manufacturer stock a minimum number of materials and sizes.An example of a specification is given in Sec.1-17. This example is for a case study of a power transmission that is presented throughout this text. The synthesis of a scheme connecting possible system elements is sometimes called the invention of the concept or concept design.This is the first and most impor- tant step in the synthesis task.Various schemes must be proposed,investigated,and

6 Mechanical Engineering Design circumstance or a set of random circumstances that arises almost simultaneously. For example, the need to do something about a food-packaging machine may be indicated by the noise level, by a variation in package weight, and by slight but perceptible vari￾ations in the quality of the packaging or wrap. There is a distinct difference between the statement of the need and the definition of the problem. The definition of problem is more specific and must include all the spec￾ifications for the object that is to be designed. The specifications are the input and out￾put quantities, the characteristics and dimensions of the space the object must occupy, and all the limitations on these quantities. We can regard the object to be designed as something in a black box. In this case we must specify the inputs and outputs of the box, together with their characteristics and limitations. The specifications define the cost, the number to be manufactured, the expected life, the range, the operating temperature, and the reliability. Specified characteristics can include the speeds, feeds, temperature lim￾itations, maximum range, expected variations in the variables, dimensional and weight limitations, etc. There are many implied specifications that result either from the designer’s par￾ticular environment or from the nature of the problem itself. The manufacturing processes that are available, together with the facilities of a certain plant, constitute restrictions on a designer’s freedom, and hence are a part of the implied specifica￾tions. It may be that a small plant, for instance, does not own cold-working machin￾ery. Knowing this, the designer might select other metal-processing methods that can be performed in the plant. The labor skills available and the competitive situa￾tion also constitute implied constraints. Anything that limits the designer’s freedom of choice is a constraint. Many materials and sizes are listed in supplier’s catalogs, for instance, but these are not all easily available and shortages frequently occur. Furthermore, inventory economics requires that a manufacturer stock a minimum number of materials and sizes. An example of a specification is given in Sec. 1–17. This example is for a case study of a power transmission that is presented throughout this text. The synthesis of a scheme connecting possible system elements is sometimes called the invention of the concept or concept design. This is the first and most impor￾tant step in the synthesis task. Various schemes must be proposed, investigated, and Figure 1–1 The phases in design, acknowledging the many feedbacks and iterations. Identification of need Definition of problem Synthesis Analysis and optimization Evaluation Presentation Iteration bud29281_ch01_002-030.qxd 11/11/2009 5:35 pm Page 6 pinnacle s-171:Desktop Folder:Temp Work:Don't Delete (Jobs):MHDQ196/Budynas:

Introduction to Mechanical Engineering Design quantified in terms of established metrics.As the fleshing out of the scheme progresses, analyses must be performed to assess whether the system performance is satisfactory or better,and,if satisfactory,just how well it will perform.System schemes that do not survive analysis are revised,improved,or discarded.Those with potential are optimized to determine the best performance of which the scheme is capable.Competing schemes are compared so that the path leading to the most competitive product can be chosen. Figure 1-1 shows that synthesis and analysis and optimization are intimately and iteratively related. We have noted,and we emphasize,that design is an iterative process in which we proceed through several steps,evaluate the results,and then return to an earlier phase of the procedure.Thus,we may synthesize several components of a system,analyze and optimize them,and return to synthesis to see what effect this has on the remaining parts of the system.For example,the design of a system to transmit power requires attention to the design and selection of individual components (e.g.,gears,bearings,shaft). However,as is often the case in design,these components are not independent.In order to design the shaft for stress and deflection,it is necessary to know the applied forces. If the forces are transmitted through gears,it is necessary to know the gear specifica- tions in order to determine the forces that will be transmitted to the shaft.But stock gears come with certain bore sizes,requiring knowledge of the necessary shaft diame- ter.Clearly,rough estimates will need to be made in order to proceed through the process,refining and iterating until a final design is obtained that is satisfactory for each individual component as well as for the overall design specifications.Throughout the text we will elaborate on this process for the case study of a power transmission design. Both analysis and optimization require that we construct or devise abstract models of the system that will admit some form of mathematical analysis.We call these mod- els mathematical models.In creating them it is our hope that we can find one that will simulate the real physical system very well.As indicated in Fig.1-1,evaluation is a significant phase of the total design process.Evaluation is the final proof of a success- ful design and usually involves the testing of a prototype in the laboratory.Here we wish to discover if the design really satisfies the needs.Is it reliable?Will it compete successfully with similar products?Is it economical to manufacture and to use?Is it easily maintained and adjusted?Can a profit be made from its sale or use?How likely is it to result in product-liability lawsuits?And is insurance easily and cheaply obtained?Is it likely that recalls will be needed to replace defective parts or systems? The project designer or design team will need to address a myriad of engineering and non-engineering questions. Communicating the design to others is the final,vital presentation step in the design process.Undoubtedly,many great designs,inventions,and creative works have been lost to posterity simply because the originators were unable or unwilling to properly explain their accomplishments to others.Presentation is a selling job.The engineer,when presenting a new solution to administrative,management,or supervisory persons,is attempting to sell or to prove to them that their solution is a better one.Unless this can be done successfully, the time and effort spent on obtaining the solution have been largely wasted.When designers sell a new idea,they also sell themselves.If they are repeatedly successful in selling ideas,designs,and new solutions to management,they begin to receive salary increases and promotions;in fact,this is how anyone succeeds in his or her profession. An excellent reference for this topic is presented by Stuart Pugh.Total Design-Integrated Methods for Successful Product Engineering.Addison-Wesley.1991.A description of the Pugh method is also provided in Chap.8,David G.Ullman,The Mechanical Design Process,3rd ed.,McGraw-Hill,2003

Introduction to Mechanical Engineering Design 7 quantified in terms of established metrics.1 As the fleshing out of the scheme progresses, analyses must be performed to assess whether the system performance is satisfactory or better, and, if satisfactory, just how well it will perform. System schemes that do not survive analysis are revised, improved, or discarded. Those with potential are optimized to determine the best performance of which the scheme is capable. Competing schemes are compared so that the path leading to the most competitive product can be chosen. Figure 1–1 shows that synthesis and analysis and optimization are intimately and iteratively related. We have noted, and we emphasize, that design is an iterative process in which we proceed through several steps, evaluate the results, and then return to an earlier phase of the procedure. Thus, we may synthesize several components of a system, analyze and optimize them, and return to synthesis to see what effect this has on the remaining parts of the system. For example, the design of a system to transmit power requires attention to the design and selection of individual components (e.g., gears, bearings, shaft). However, as is often the case in design, these components are not independent. In order to design the shaft for stress and deflection, it is necessary to know the applied forces. If the forces are transmitted through gears, it is necessary to know the gear specifica￾tions in order to determine the forces that will be transmitted to the shaft. But stock gears come with certain bore sizes, requiring knowledge of the necessary shaft diame￾ter. Clearly, rough estimates will need to be made in order to proceed through the process, refining and iterating until a final design is obtained that is satisfactory for each individual component as well as for the overall design specifications. Throughout the text we will elaborate on this process for the case study of a power transmission design. Both analysis and optimization require that we construct or devise abstract models of the system that will admit some form of mathematical analysis. We call these mod￾els mathematical models. In creating them it is our hope that we can find one that will simulate the real physical system very well. As indicated in Fig. 1–1, evaluation is a significant phase of the total design process. Evaluation is the final proof of a success￾ful design and usually involves the testing of a prototype in the laboratory. Here we wish to discover if the design really satisfies the needs. Is it reliable? Will it compete successfully with similar products? Is it economical to manufacture and to use? Is it easily maintained and adjusted? Can a profit be made from its sale or use? How likely is it to result in product-liability lawsuits? And is insurance easily and cheaply obtained? Is it likely that recalls will be needed to replace defective parts or systems? The project designer or design team will need to address a myriad of engineering and non-engineering questions. Communicating the design to others is the final, vital presentation step in the design process. Undoubtedly, many great designs, inventions, and creative works have been lost to posterity simply because the originators were unable or unwilling to properly explain their accomplishments to others. Presentation is a selling job. The engineer, when presenting a new solution to administrative, management, or supervisory persons, is attempting to sell or to prove to them that their solution is a better one. Unless this can be done successfully, the time and effort spent on obtaining the solution have been largely wasted. When designers sell a new idea, they also sell themselves. If they are repeatedly successful in selling ideas, designs, and new solutions to management, they begin to receive salary increases and promotions; in fact, this is how anyone succeeds in his or her profession. 1 An excellent reference for this topic is presented by Stuart Pugh, Total Design—Integrated Methods for Successful Product Engineering, Addison-Wesley, 1991. A description of the Pugh method is also provided in Chap. 8, David G. Ullman, The Mechanical Design Process, 3rd ed., McGraw-Hill, 2003. bud29281_ch01_002-030.qxd 11/11/2009 5:35 pm Page 7 pinnacle s-171:Desktop Folder:Temp Work:Don't Delete (Jobs):MHDQ196/Budynas:

Mechanical Engineering Design Design Considerations Sometimes the strength required of an element in a system is an important factor in the determination of the geometry and the dimensions of the element.In such a situation we say that strength is an important design consideration.When we use the expression design consideration,we are referring to some characteristic that influences the design of the element or,perhaps,the entire system.Usually quite a number of such charac- teristics must be considered and prioritized in a given design situation.Many of the important ones are as follows(not necessarily in order of importance): 1 Functionality 14 Noise 2 Strength/stress 15 Styling 3 Distortion/deflection/stiffness 16 Shape Wear 17 Size Corrosion 18 Control 6 Safety 19 Thermal properties 7 Reliability 20 Surface 8 Manufacturability 21 Lubrication 9 Utility 22 Marketability 10 Cost 23 Maintenance 11 Friction 24 Volume 12 Weight 25 Liability 13 Life 26 Remanufacturing/resource recovery Some of these characteristics have to do directly with the dimensions,the material,the processing,and the joining of the elements of the system.Several characteristics may be interrelated,which affects the configuration of the total system 1-4 Design Tools and Resources Today,the engineer has a great variety of tools and resources available to assist in the solution of design problems.Inexpensive microcomputers and robust computer soft- ware packages provide tools of immense capability for the design,analysis,and simu- lation of mechanical components.In addition to these tools,the engineer always needs technical information,either in the form of basic science/engineering behavior or the characteristics of specific off-the-shelf components.Here,the resources can range from science/engineering textbooks to manufacturers'brochures or catalogs.Here too,the computer can play a major role in gathering information.2 Computational Tools Computer-aided design (CAD)software allows the development of three-dimensional (3-D)designs from which conventional two-dimensional orthographic views with auto- matic dimensioning can be produced.Manufacturing tool paths can be generated from the 3-D models,and in some cases,parts can be created directly from a 3-D database by using a rapid prototyping and manufacturing method(stereolithography)-paperless manufac- turing!Another advantage of a 3-D database is that it allows rapid and accurate calcula- tions of mass properties such as mass,location of the center of gravity,and mass moments of inertia.Other geometric properties such as areas and distances between points are likewise easily obtained.There are a great many CAD software packages available such 2An excellent and comprehensive discussion of the process of"gathering information"can be found in Chap.4,George E.Dieter,Engineering Design,A Materials and Processing Approach,3rd ed.. McGraw-Hill.New York.2000

8 Mechanical Engineering Design Design Considerations Sometimes the strength required of an element in a system is an important factor in the determination of the geometry and the dimensions of the element. In such a situation we say that strength is an important design consideration. When we use the expression design consideration, we are referring to some characteristic that influences the design of the element or, perhaps, the entire system. Usually quite a number of such charac￾teristics must be considered and prioritized in a given design situation. Many of the important ones are as follows (not necessarily in order of importance): 1 Functionality 14 Noise 2 Strength/stress 15 Styling 3 Distortion/deflection/stiffness 16 Shape 4 Wear 17 Size 5 Corrosion 18 Control 6 Safety 19 Thermal properties 7 Reliability 20 Surface 8 Manufacturability 21 Lubrication 9 Utility 22 Marketability 10 Cost 23 Maintenance 11 Friction 24 Volume 12 Weight 25 Liability 13 Life 26 Remanufacturing/resource recovery Some of these characteristics have to do directly with the dimensions, the material, the processing, and the joining of the elements of the system. Several characteristics may be interrelated, which affects the configuration of the total system. 1–4 Design Tools and Resources Today, the engineer has a great variety of tools and resources available to assist in the solution of design problems. Inexpensive microcomputers and robust computer soft￾ware packages provide tools of immense capability for the design, analysis, and simu￾lation of mechanical components. In addition to these tools, the engineer always needs technical information, either in the form of basic science/engineering behavior or the characteristics of specific off-the-shelf components. Here, the resources can range from science/engineering textbooks to manufacturers’ brochures or catalogs. Here too, the computer can play a major role in gathering information.2 Computational Tools Computer-aided design (CAD) software allows the development of three-dimensional (3-D) designs from which conventional two-dimensional orthographic views with auto￾matic dimensioning can be produced. Manufacturing tool paths can be generated from the 3-D models, and in some cases, parts can be created directly from a 3-D database by using a rapid prototyping and manufacturing method (stereolithography)—paperless manufac￾turing! Another advantage of a 3-D database is that it allows rapid and accurate calcula￾tions of mass properties such as mass, location of the center of gravity, and mass moments of inertia. Other geometric properties such as areas and distances between points are likewise easily obtained. There are a great many CAD software packages available such 2 An excellent and comprehensive discussion of the process of “gathering information” can be found in Chap. 4, George E. Dieter, Engineering Design, A Materials and Processing Approach, 3rd ed., McGraw-Hill, New York, 2000. bud29281_ch01_002-030.qxd 11/11/2009 5:35 pm Page 8 pinnacle s-171:Desktop Folder:Temp Work:Don't Delete (Jobs):MHDQ196/Budynas:

Introduction to Mechanical Engineering Design as Aries,AutoCAD,CadKey,I-Deas,Unigraphics,Solid Works,and ProEngineer,to name a few. The term computer-aided engineering (CAE)generally applies to all computer- related engineering applications.With this definition,CAD can be considered as a sub- set of CAE.Some computer software packages perform specific engineering analysis and/or simulation tasks that assist the designer,but they are not considered a tool for the creation of the design that CAD is.Such software fits into two categories:engineering- based and non-engineering-specific.Some examples of engineering-based software for mechanical engineering applications-software that might also be integrated within a CAD system-include finite-element analysis(FEA)programs for analysis of stress and deflection (see Chap.19),vibration,and heat transfer (e.g.,Algor,ANSYS,and MSC/NASTRAN);computational fluid dynamics(CFD)programs for fluid-flow analy- sis and simulation (e.g.,CFD++,FIDAP,and Fluent);and programs for simulation of dynamic force and motion in mechanisms (e.g.,ADAMS,DADS,and Working Model). Examples of non-engineering-specific computer-aided applications include software for word processing,spreadsheet software (e.g.,Excel,Lotus,and Quattro-Pro),and mathematical solvers(e.g.,Maple,MathCad,MATLAB,3 Mathematica,and TKsolver). Your instructor is the best source of information about programs that may be available to you and can recommend those that are useful for specific tasks.One caution,however: Computer software is no substitute for the human thought process.You are the driver here; the computer is the vehicle to assist you on your journey to a solution.Numbers generated by a computer can be far from the truth if you entered incorrect input,if you misinterpreted the application or the output of the program,if the program contained bugs,etc.It is your responsibility to assure the validity of the results,so be careful to check the application and results carefully,perform benchmark testing by submitting problems with known solu- tions,and monitor the software company and user-group newsletters. Acquiring Technical Information We currently live in what is referred to as the information age,where information is gen- erated at an astounding pace.It is difficult,but extremely important,to keep abreast of past and current developments in one's field of study and occupation.The reference in Footnote 2 provides an excellent description of the informational resources available and is highly recommended reading for the serious design engineer.Some sources of information are: Libraries(community,university,and private).Engineering dictionaries and encyclo- pedias,textbooks,monographs,handbooks,indexing and abstract services,journals, translations,technical reports,patents,and business sources/brochures/catalogs Government sources.Departments of Defense,Commerce,Energy,and Transportation; NASA;Government Printing Office;U.S.Patent and Trademark Office;National Technical Information Service;and National Institute for Standards and Technology. Professional societies.American Society of Mechanical Engineers,Society of Manufacturing Engineers,Society of Automotive Engineers,American Society for Testing and Materials,and American Welding Society. Commercial vendors.Catalogs,technical literature,test data,samples,and cost information. Internet.The computer network gateway to websites associated with most of the categories listed above.4 MATLAB is a registered trademark of The MathWorks,Inc. Some helpful Web resources,to name a few,include www.globalspec.com,www.engnetglobal.com, www.efunda.com,www.thomasnet.com,and www.uspto.gov

Introduction to Mechanical Engineering Design 9 as Aries, AutoCAD, CadKey, I-Deas, Unigraphics, Solid Works, and ProEngineer, to name a few. The term computer-aided engineering (CAE) generally applies to all computer￾related engineering applications. With this definition, CAD can be considered as a sub￾set of CAE. Some computer software packages perform specific engineering analysis and/or simulation tasks that assist the designer, but they are not considered a tool for the creation of the design that CAD is. Such software fits into two categories: engineering￾based and non-engineering-specific. Some examples of engineering-based software for mechanical engineering applications—software that might also be integrated within a CAD system—include finite-element analysis (FEA) programs for analysis of stress and deflection (see Chap. 19), vibration, and heat transfer (e.g., Algor, ANSYS, and MSC/NASTRAN); computational fluid dynamics (CFD) programs for fluid-flow analy￾sis and simulation (e.g., CFD++, FIDAP, and Fluent); and programs for simulation of dynamic force and motion in mechanisms (e.g., ADAMS, DADS, and Working Model). Examples of non-engineering-specific computer-aided applications include software for word processing, spreadsheet software (e.g., Excel, Lotus, and Quattro-Pro), and mathematical solvers (e.g., Maple, MathCad, MATLAB,3 Mathematica, and TKsolver). Your instructor is the best source of information about programs that may be available to you and can recommend those that are useful for specific tasks. One caution, however: Computer software is no substitute for the human thought process. You are the driver here; the computer is the vehicle to assist you on your journey to a solution. Numbers generated by a computer can be far from the truth if you entered incorrect input, if you misinterpreted the application or the output of the program, if the program contained bugs, etc. It is your responsibility to assure the validity of the results, so be careful to check the application and results carefully, perform benchmark testing by submitting problems with known solu￾tions, and monitor the software company and user-group newsletters. Acquiring Technical Information We currently live in what is referred to as the information age, where information is gen￾erated at an astounding pace. It is difficult, but extremely important, to keep abreast of past and current developments in one’s field of study and occupation. The reference in Footnote 2 provides an excellent description of the informational resources available and is highly recommended reading for the serious design engineer. Some sources of information are: • Libraries (community, university, and private). Engineering dictionaries and encyclo￾pedias, textbooks, monographs, handbooks, indexing and abstract services, journals, translations, technical reports, patents, and business sources/brochures/catalogs. • Government sources. Departments of Defense, Commerce, Energy, and Transportation; NASA; Government Printing Office; U.S. Patent and Trademark Office; National Technical Information Service; and National Institute for Standards and Technology. • Professional societies. American Society of Mechanical Engineers, Society of Manufacturing Engineers, Society of Automotive Engineers, American Society for Testing and Materials, and American Welding Society. • Commercial vendors. Catalogs, technical literature, test data, samples, and cost information. • Internet. The computer network gateway to websites associated with most of the categories listed above.4 3 MATLAB is a registered trademark of The MathWorks, Inc. 4 Some helpful Web resources, to name a few, include www.globalspec.com, www.engnetglobal.com, www.efunda.com, www.thomasnet.com, and www.uspto.gov. bud29281_ch01_002-030.qxd 11/11/2009 5:35 pm Page 9 pinnacle s-171:Desktop Folder:Temp Work:Don't Delete (Jobs):MHDQ196/Budynas:

10 Mechanical Engineering Design This list is not complete.The reader is urged to explore the various sources of information on a regular basis and keep records of the knowledge gained. 1-5 The Design Engineer's Professional Responsibilities In general,the design engineer is required to satisfy the needs of customers(man- agement,clients,consumers,etc.)and is expected to do so in a competent,responsi- ble,ethical,and professional manner.Much of engineering course work and practical experience focuses on competence,but when does one begin to develop engineering responsibility and professionalism?To start on the road to success,you should start to develop these characteristics early in your educational program.You need to cul- tivate your professional work ethic and process skills before graduation,so that when you begin your formal engineering career,you will be prepared to meet the challenges. It is not obvious to some students,but communication skills play a large role here, and it is the wise student who continuously works to improve these skills-even if it is not a direct requirement of a course assignment!Success in engineering (achieve- ments,promotions,raises,etc.)may in large part be due to competence but if you can- not communicate your ideas clearly and concisely,your technical proficiency may be compromised. You can start to develop your communication skills by keeping a neat and clear journal/logbook of your activities,entering dated entries frequently.(Many companies require their engineers to keep a journal for patent and liability concerns.)Separate journals should be used for each design project (or course subject).When starting a project or problem,in the definition stage,make journal entries quite frequently.Others, as well as yourself,may later question why you made certain decisions.Good chrono- logical records will make it easier to explain your decisions at a later date. Many engineering students see themselves after graduation as practicing engineers designing,developing,and analyzing products and processes and consider the need of good communication skills,either oral or writing,as secondary.This is far from the truth.Most practicing engineers spend a good deal of time communicating with others, writing proposals and technical reports,and giving presentations and interacting with engineering and nonengineering support personnel.You have the time now to sharpen your communication skills.When given an assignment to write or make any presenta- tion,technical or nontechnical,accept it enthusiastically,and work on improving your communication skills.It will be time well spent to learn the skills now rather than on the job. When you are working on a design problem,it is important that you develop a systematic approach.Careful attention to the following action steps will help you to organize your solution processing technique. Understand the problem.Problem definition is probably the most significant step in the engineering design process.Carefully read,understand,and refine the problem statement. Identify the knowns.From the refined problem statement,describe concisely what information is known and relevant. Identify the unknowns and formulate the solution strategy.State what must be deter- mined,in what order,so as to arrive at a solution to the problem.Sketch the compo- nent or system under investigation,identifying known and unknown parameters Create a flowchart of the steps necessary to reach the final solution.The steps may require the use of free-body diagrams;material properties from tables;equations

10 Mechanical Engineering Design This list is not complete. The reader is urged to explore the various sources of information on a regular basis and keep records of the knowledge gained. 1–5 The Design Engineer’s Professional Responsibilities In general, the design engineer is required to satisfy the needs of customers (man￾agement, clients, consumers, etc.) and is expected to do so in a competent, responsi￾ble, ethical, and professional manner. Much of engineering course work and practical experience focuses on competence, but when does one begin to develop engineering responsibility and professionalism? To start on the road to success, you should start to develop these characteristics early in your educational program. You need to cul￾tivate your professional work ethic and process skills before graduation, so that when you begin your formal engineering career, you will be prepared to meet the challenges. It is not obvious to some students, but communication skills play a large role here, and it is the wise student who continuously works to improve these skills—even if it is not a direct requirement of a course assignment! Success in engineering (achieve￾ments, promotions, raises, etc.) may in large part be due to competence but if you can￾not communicate your ideas clearly and concisely, your technical proficiency may be compromised. You can start to develop your communication skills by keeping a neat and clear journal/logbook of your activities, entering dated entries frequently. (Many companies require their engineers to keep a journal for patent and liability concerns.) Separate journals should be used for each design project (or course subject). When starting a project or problem, in the definition stage, make journal entries quite frequently. Others, as well as yourself, may later question why you made certain decisions. Good chrono￾logical records will make it easier to explain your decisions at a later date. Many engineering students see themselves after graduation as practicing engineers designing, developing, and analyzing products and processes and consider the need of good communication skills, either oral or writing, as secondary. This is far from the truth. Most practicing engineers spend a good deal of time communicating with others, writing proposals and technical reports, and giving presentations and interacting with engineering and nonengineering support personnel. You have the time now to sharpen your communication skills. When given an assignment to write or make any presenta￾tion, technical or nontechnical, accept it enthusiastically, and work on improving your communication skills. It will be time well spent to learn the skills now rather than on the job. When you are working on a design problem, it is important that you develop a systematic approach. Careful attention to the following action steps will help you to organize your solution processing technique. • Understand the problem. Problem definition is probably the most significant step in the engineering design process. Carefully read, understand, and refine the problem statement. • Identify the knowns. From the refined problem statement, describe concisely what information is known and relevant. • Identify the unknowns and formulate the solution strategy. State what must be deter￾mined, in what order, so as to arrive at a solution to the problem. Sketch the compo￾nent or system under investigation, identifying known and unknown parameters. Create a flowchart of the steps necessary to reach the final solution. The steps may require the use of free-body diagrams; material properties from tables; equations bud29281_ch01_002-030.qxd 11/11/2009 5:35 pm Page 10 pinnacle s-171:Desktop Folder:Temp Work:Don't Delete (Jobs):MHDQ196/Budynas: