Introduction Screen Titles Course Objective and Overview Content and Format Proposed Study Guide Installation and Operation Introduction - 1 - C.F. Zorowski 2002
Introduction - 2 - C.F. Zorowski 2002
Course Objective and Overview The Design for Strength and Endurance instructional package was created to meet the needs of engineering life-long learners who desire through self-study to continue their professional development. It was designed with the instructional objective to provide a learning environment that overcomes the frustrations and difficulties often encountered by the self-learner in attempting to decipher and understand commonly used text books on subjects of interest. A clarification is also in order at this point to establish the manner in which the activity of design will be dealt with in this unique instructional approach. The preferred definition of the word design, according to Webster, is a mental process or scheme in which the means to an end are laid down. An acceptable definition of design in the context of engineering might well be an activity under taken by engineers that results in the creation of the description and specification of a device, system or process that meets some recognized or identified need of society based on existing technology while making use of available natural resources within some specified set of constraints applicable to the circumstance in question. Although the engineering definition is lengthy and possesses greater specificity there can be no disagreement of its consistency with the more generic Webster definition. However, it is precisely the greater specificity of design as an engineering process that requires further consideration of the subject content of this educational module and its manner of presentation. The word design in the title Design for Strength and Endurance is not meant to refer to the process of creating a description of the size, form, shape or operational characteristics of some physical device or system. The purpose of this educational module is to develop and describe the application of analytical predictive processes used to determine whether a proposed physical design will satisfy the criteria and constraints that will insure its mechanical strength and life endurance requirements. Throughout the instructional treatment that follows application of these predictive processes will be limited to what might be classified generically as physical parts in some mechanical device. More specifically, the size, shape, loadings and materials of the bars, beams, shafts and other similar components treated will always be specified. The subject of Design for Strength and Endurance is dealt with in this fashion to more readily achieve the instructional objective of providing the student with the knowledge and practice to determine the static strength, fatigue life and ultimate strength of mechanical components as they are influenced by their geometry, external loading and material properties. Having the student develop effective levels of competence in the following specific topics will fulfill this educational objective: 1. Introductory definitions and concepts. 2. Analysis of two dimensional stress states. 3. Two dimensional strain states and Hooke s law. 4. Static strength behavior of materials. 5. Effect of processing on material properties, 6. Theories for predicting static ductile and brittle failure. 7. Nominal and statistical factors of safety. 8. Cyclic reversed loading effects on material properties. 9. Fatigue life prediction under general fluctuating loads. 10. Effect of part geometry on limit loading. Knowledge prerequisites for this study are the basic concepts provided in an introductory engineering course in strength of materials. Some repetition of these earlier materials is included to provide their thorough understanding to insure complete familiarity and confidence in their application as the entire subject is developed. Introduction - 3 - C.F. Zorowski 2002
Introduction - 4 - C.F. Zorowski 2002
Content and Format The complete Design for Strength and Endurance instructional package consists of two items, a CD disk and a printed Instructional Supplement. The disk contains a multimedia audio enhanced graphical presentation of the subject content. This covers the knowledge required to both understand and analytically predict the static strength, fatigue life and limit load capacity of mechanical parts subjected to static and fluctuating external loading. The complete CD presentation consists of ten selfcontained chapters that can be played independently using installed software together with the disk. The ten chapters contain some 300 graphically illustrated and animated screens accompanied by complete audio explanations of the presented material. Navigation aids are provided on each screen. This permits the viewer to stop the presentation, exit the chapter, replay the audio or select other screens in the chapter or any other chapter. Capability to view the text of the audio in a pop up window is also available. Each chapter includes both example and interactive exercise problems that illustrate the application of the material covered. Hyperlinks to solutions of the interactive problem are included to allow the viewer to verify their own results. At the end of each chapter Review Exercises with immediate feedback are provided for the viewer to check their general knowledge of the material covered. Also included is an off line exercise for practice in the application of the chapter concepts beyond the presentation. Instructions for the use of the software program on the disk are covered in the section on Installation and Operation. The Instructional Supplement is provided as an additional learning aid and ready hard copy reference to all materials presented on the CD disk. Its contents include grayscale copies of all instructional screens on the CD together with the printed script used for the audio enhancement of each screen. The printed supplement can be used in a variety of ways to enhance the instructional experience to best suit the preferred learning style of the student. Only two screens appear on each page. This provides space for the viewer to take notes or make other relevant comments while listening to the disk presentation. With the full text of the audio provided important phrases and concepts in the text as well as important equations on the graphics can be highlighted as desired by the student. The interactive problem solutions are separated from the main chapter content to reduce the temptation to look up the answer before attempting to solve the problem. Quick visual reference from one screen to another in any given chapter is readily possible as might be helpful in the solution of the Off Line Exercise. Also, quick reference to equations and physical concepts is readily available with use of the index in the Appendix of the supplement. Imaginative serious students of the subject will undoubtedly employ other complementary uses of the CD disk together with the Instructional Supplement. At the end of each chapter are solutions to the interactive practice problems included in the chapter. Also included with each chapter is a short quiz that students can use to further evaluate their comprehension of the chapter content. These are most effectively taken as timed ten-minute exercises without reference to the supplement or disk. Solutions to the quizzes are provided in the Appendix. Solutions to the Off Line Exercises are provided in the Appendix along with a topical Index to provide a ready reference to specific concepts and subjects included through out the Instructional Supplement. Finally, the Appendix includes instructions for the student to undertake and carry out an extended formal project representative of a real practical problem. This more extensive final exercise provides the learner with an experience that synthesizes the application of all knowledge content included in the educational module. Introduction - 5 - C.F. Zorowski 2002
Introduction - 6 - C.F. Zorowski 2002
Suggested Study Guide Although individual learning styles may differ widely the following guide is suggested as a study guide to achieve both effective coverage and self-evaluation of the understanding and proper application of the knowledge content of Design for Strength and Endurance. First, it is useful to recognize that the ten chapters of the module can be subdivided into the following areas of emphasis: 1. Review of the fundamental applicable concept of strength of materials. (Chapter 1) 2. Analytical and graphical analysis of general states of stress and strain and their relationship as dictated by Hooke s Law. (Chapter 2 &3) 3. Typical mechanical properties of metals under static loading and the effects of mechanical and thermal processing. (Chapters 4&5) 4. Theories for predicting the static ductile and brittle failure of mechanical parts together with nominal and statistical factors of safety. (Chapter 6 & 7) 5. Effects of reversed loading on material properties and fatigue failure analysis under cyclic loading. (Chapters 8 & 9) 6. Support geometry effects on the limit loading of beam elements. (Chapter 10) Area 1 is preparation for the remainder of the subject. Areas 2 and 3 cover the fundamental required for consideration of Area 4. Area 5 extends the static analysis to application of fluctuating loads and Area 6 introduces the concept of ultimate loading. The chapters should be covered in the order listed for continuity. It is recommended that the study of each chapter be started with the audio enhanced presentation provided on the CD. As suggested on the chapter index page proceed through all pages in a sequential pattern. As the audio proceeds do not hesitate to interrupt the presentation (stop button) and start it over (replay button) if you do not understand the explanation. The page may be replayed as many times as necessary. The manual may be used during this process for reference to the audio text, highlighting important items or making relevant notes. The audio text is also available on the pages of the CD presentation by clicking on the text button after the audio is complete or has been stopped. Complete interactive exercises as they are encountered to evaluate your understanding of the most recent material covered. Check your results by clicking on the solution button on the page. If correct return to the presentation and proceed to the next page, otherwise satisfy your self that you understand where you went wrong. You may return to the chapter index page (index button) to review any page that may be useful. Use the Review Exercises at the end of the chapter for an immediately evaluation of your general knowledge of the important concepts covered. Make use of the Hot words (links to other screens) as appropriate. At this point undertake the solution of the Off Line Exercise. The supplement may again be useful at this point to quickly review or reference important equations and concepts. When completed check your solution against the solution listed in the appendix. Finally, take the quiz at the end of the chapter without reference to either the CD or the supplement and then check your answers against those provided in the Appendix. If you are satisfied with your comprehension of the content of the chapter proceed on. When you have completed all ten chapters it is recommended that you undertake the project presented in the Appendix. This activity is more extensive than the preceding exercises. It provides an experience in synthesizing all the material covered with the added requirement of requiring assumptions concerning aspects of the situation presented that are not defined. The value gained from this activity will be in proportion to the time and effort committed. Introduction - 7 - C.F. Zorowski 2002
Introduction - 8 - C.F. Zorowski 2002
Installation and Operation The Design for Strength and Endurance CD instructional module is a self-contained PowerAudio TM instructional product created in Asymetrix Toolbook II Assistant TM. Be sure to read the following installation and operating instructions before proceeding. Hardware/Software Requirements: PC running Windows 95/98/2000 or NT CD 2x or higher drive (the faster the better!) Sound card with speakers (capable of playing wave and midi files). MS Windows media player To Install CD Software Program (First, close all running applications before installing Design for Strength and Endurance) 1. Insert the Design for Strength and Endurance disc in the CD ROM drive. 2. From the Start menu choose Run in Windows 95/98/2000 or NT. 3. In the Run window, type location from which program is to be installed (for example D:\). Then type setup.exe. (see note below) 4. Click OK and follow instructions on screen in Install Wizard. 5. Choose either typical or custom installation. Typical places only the program operating system on hard drive with all remaining files left on CD. Custom permits installation of educational module files on hard drive. This can require significantly more storage space. Advantage of installation on hard drive is more rapid transfer between chapter and audio files. 6. Restart computer. (Note: Following step 3 above a window may appear with icons of files on the CD disc. If this occurs double click on setup.exe file and proceed with step 4) Alternative: 1. Insert the Design for Strength and Endurance disc in the CD drive. 2. Open Windows file Explorer application. 3. Double click on CD drive to list files. 4. Select and double click on setup.exe file. 5. Install Wizard will appear. 6. Follow steps 5 and 6 as previously. If Typical installation is chosen (or all files are not placed on hard drive) CD must remain or be placed in drive to play complete educational module presentation. To Run Design for Strength and Endurance : Or 1. From the Start menu in Windows 95/98/2000 or NT point to Programs then Design for Strength and Endurance shortcut. 2. Click on Begin Module file. 3. Program will begin and detailed navigation instructions will be provided on the Main Menu page 1. From the Start menu in Windows 95/98/2000 or NT point to Programs, then to Design for Strength and Endurance. 2. Click on any Chap. _ desired. 3. Program will open at Chapter selected. To Exit Design for Strength and Endurance: 1. From any page in any chapter click on the Stop button until Replay button appears. 2. Click on Exit button. 3. The Exit page will appear and allow two choices: to exit the module or return to the Main Menu. Introduction - 9 - C.F. Zorowski 2002
Navigation, Audio and Special Features: Six navigation and operation buttons always appear in the bottom border of each page in the module. Their functions are as described below: Stops audio and forwards to next page. Click Here Return Appears when audio is finished and Next Page button should be clicked. Returns reader from problem solution page to next page in chapter. Stops audio and returns to previous page. (Note: Above navigation buttons are only active if pointers are highlighted. If active they will respond even if audio is playing.) Stop Exit Text Index Stops audio and slide animation. On repeated clicks will bring up Replay button and Click Here button. Transfers to exit page to permit Exiting module or return to Main Menu page Shows popup window in lower right of page with text of audio for that page. Returns to Chapter Index Page for selection of a specific page Four additional operational buttons that appear intermittently when the audio finishes are the Replay, Click Here, Return and Main Menu buttons. Replay Replays page from the beginning with audio and all slide animation Main Menu Some Special Notes Returns reader to main Chapter Menu to permit selection of another chapter or exit module 1. Older sound cards may not be equipped to play midi (synthesizer music) files. If no music occurs when second page of Begin Module appears wait 30 seconds and next page with audio will come up automatically. 2. If audio volume requires adjustment refer to your operating systems manual (Windows 95/98/2000 or NT) for instructions on changing volume of wave files. 3. Pages of Design for Strength and Endurance education module should fill about 2/3 of monitor screen. Size of presentation window can be adjusted. Refer to your operating systems manual (Windows 95/98/2000 or NT) for instructions on changing monitor settings. 4. Pop up windows are closed by clicking on X in top right corner. 5. If content, video and text chapter files remain on CD rather than loaded on hard drive transfer time of hyperlinks (special buttons) may slow down depending on speed of computer. Click once to activate hyperlink and apply patience! Hour Glass icon will appear indicating transfer is underway, Introduction - 10 - C.F. Zorowski 2002