HOW TO PASS THE MACHINE DESIGN AND MATERIALS PE EXAM

Save time, focus your studying, and increase your chances of passing by following this method. This article does not focus on generic tips, like what to bring to the exam and the logistics for the day.. This article focuses on passing the exam, scoring high and completing the exam in the slotted time.

1. Print out the NCEES Outline

The NCEES administers the exam and also provides an outline with the topics and the number of questions per topic to be covered. Print out this outline and place it in a 3-ring binder. Then create dividers for each major topic as shown below.

Basic Engineering Practice (9)

Engineering Science and Mechanics (1))

Material Properties (8)

Strength of Materials (10)

Vibration (3)

Mechanical Components (18)

Joints & Fasteners (12)

Supportive Knowledge (10)

This will help to lay the framework of your studying and will make sure that you are studying the correct material.

Find the syllabus under the Exam Specifications of the NCEES website.

2. Think Principle or Application & Think in 6 minutes

The NCEES outline will guide you to the correct topics for studying, but how in depth do you go when studying each topic? The answer is, the test should contain material that is relevant to a practicing engineer and should be simple enough to solve in 6 minutes. The PE exam is a test of whether you are competent enough to practice in the field of Mechanical Engineering, not on whether you can derive complex formulas. It should be based on problems that you would normally encounter in the field.

Therefore, when studying, think about the following questions:

(a) How can this topic be applied in real life situations?

Knowing how a topic is used in real life will help you expand your understanding of its purpose, while preparing you with how it can be presented in problems. Ask yourself, "What is the purpose of this equation?" and "When would I use this in real life applications?"

For example, when studying fastener groups, realize its purpose is to treat the individual fasteners as a single group in order to determine the centroid and moment of the group. Then individual stresses can be calculated for each fastener. When would you use this in real life? You would likely use this for creating equipment and piping supports.

(b) What information would I be given in the field to solve these problems?

Along the same theme of real life situations, the exam will most likely give you variables that would be given to you in real life. The known values will be characteristics that are measurable or given in the field, while the unknowns are what would normally be calculated.

For example, with fastener groups, the standard bolt strength is 70 ksi, so this will most likely be given to you. In addition, there are only a few bolt patterns that are used when securing one component to another. These patterns are symmetrical, which makes the analysis easier. These questions typically either want you to determine the size of the bolts or determine the stress within a specific bolt size. When studying each topic, think of the various ways a problem could be encountered based on the possible unknowns. This will help you be prepared for possible variations of a question and will help you to better understand a concept.

(c) Do I understand the concept of how to solve these problems?

One of the most important things you can do while studying is being sure you understand the concept. Many problems will be a variation of something you may have come across earlier and the only way to overcome them is to understand the concept. The NCEES practice exam shows that there are also a significant amount of conceptual, non-numerical problems. Finally, the test maker will add extraneous information that is intended to throw you off if you do not truly understand the question.

Common conceptual problems will create situations where, if this component fails, or if this value increases, etc., then what happens to another part of the system. Tip: In machine design & materials, the thickness, height, width, temperature, span distance etc are all examples of values that can be varied to affect the stress within a component. As you study the various components (shafts, bearings, beams, couplings, keys, springs, screws, bolts, rivets, belts, pulleys, gears, pressure vessels, adhesives), think about how the previously mentioned variables affect the strength, fatigue and failure of the component.

(d) Can this be solved in 6 minutes?

Finally, if it takes you more than a 3–4 steps to solve a problem, then something is probably wrong. If this happens, rewind, take a step back, and ask yourself, "Am I understanding the problem correctly?"

3. Know your resources

Below is a list of a few key references that I have found to be the most helpful for the exam. Because time is limited, it is essential to be able to quickly navigate through these resources, especially the NEC. Tab the important sections and add page number references to your equations list/cheat sheets.

• NCEES Practice Exam

• Engineering Pro Guides Machine Design & Materials PE Study Guide

• Machinery's Handbook

• Shigley's Mechanical Engineering Design

• Economics - Interest Rates Tables

For more details and additional resources organized by topic, refer to "Complete List of the Must Have References for the Machine Design and Materials PE Exam."

4. Know Shigley’s and Machinery’s Handbook

There are two main books that you need as references for the Machine Design and Materials PE exam, (1) Shigley’s Mechanical Engineering Design and (2) Machinery’s Handbook. I think that if you had unlimited time and this book, then you could easily pass the exam. Unfortunately, you do not have unlimited time, so you need to be very familiar with these books to be able to look up any reference that you may need or any section that you may struggle with on the exam. On the exam, you should try to solve the problem first through your memory, then your cheat sheets and as a last resort you should use these two references. When you are studying you should look through the following chapters and be familiar with the information in the chapters.

a. Shigley’s Chapters to Read: You do not need to read the entire book, although I do recommend at least reading and taking notes on the following key areas:

(1) Basics: Load and stress analysis, deflection and stiffness.

(2) Failure Prevention: Failures resulting from static loading and from variable loading.

(3) Design of Mechanical Elements: Shafts, screws, fasteners, welding, springs, rolling contact bearings, lubrication, journal bearings, gears, helical gears, bevel gears, worm gears, clutches, brakes and couplings.

b. Machinery’s Handbook: You do not need to read the entire book, although I do recommend at least reading and taking notes on the following key areas:

(1) Mechanics and Strength of Materials: Mechanics, velocity, acceleration, strength of materials, beams, columns, shafts and springs.

(2) Dimensioning, Gaging and Measuring: Allowances, tolerances and fits.

(3) Fasteners: Torque, tension and inch threaded fasteners.

(4) Threading: Screw threads, unified screw threads, acme screw threads and buttress screw threads.

(5) Gears, Splines and Cams: Bevel, worm, helical and cams.

(6) Machine Elements: Bearings, lubrication, clutches, brakes, keys, belts, lead-screws and adhesives.

c. Tabs: The index is the best way to find things in the book. Test yourself with being able to use the index with Engineering Pro Guides practice questions. There is a decent list of questions that will help you familiarize yourself with the Machinery’s Handbook and Shigley’s Mechanical Engineering Design. However, since looking through the index still consumes time, please tab the pages that you use during your studying.

d. Key Tables: Know where the main tables are throughout the book. Practice using these tables with item (c) above.

• Machinery’s Handbook: Bolt strength tables

• Machinery’s Handbook: Material properties tables

• Shigley’s: Physical constants of materials

• Shigley’s: Shear, moment and bending beam diagrams

• Shigley’s: Tolerances and fits for shafts and holes

• Shigley’s: Geometric properties of sections (I, J, A)

• Shigley’s: Mechanical properties of metals and other materials

5. Know the test format. Be aware of unnecessary information.

At the start, I would recommend taking the NCEES Practice Exam to familiarize yourself with how the test is formatted, the types of questions to study, the difficulty of the problems, and the style of the questions. You will notice the test questions in the practice exam have three types: reference lookup, calculations, or conceptual. The questions may be convoluted with unnecessary information, so be sure to avoid getting tricked by staying focused on the main question.

At a minimum, you should be very familiar with the concepts of all the questions in the NCEES practice exam; the actual test will be similar to this format. I highly recommend bringing the NCEES practice exam into the test, with your notes on how to solve these problems.

6. Use your time wisely: Go through the test in 3 Passes

Each problem is scored equally on the test. Therefore, instead of trying to solve each problem in order and getting stuck on the difficult ones, use the following process. When doing this, it is important to also continuously check your bubbles to be sure your answers stay aligned with the correct problem.

(1) First Pass: Go through the test.

• As soon as you recognize the problem as a reference look-up problem, mark it in your book as the reference type. Completely skip this problem for the second pass.

• If the problem is not a reference look-up type and you do not immediately recognize how to solve it, then mark it and skip to the next one. If you can solve it, then answer it. This has two benefits: The first is using your time better on problems you know how to do. The second is the subsequent problems may stir your memory or bring you across a resource that could help you solve the skipped problem.

(2) Second Pass: On your second pass do all the problems that require you to use your reference books. The first problems should be problems that you can complete with your cheat sheets or memory, but the second pass are problems that require you to open your reference books.

(3) Third Pass: Finish the problems that were left unsolved.

(4) If you have time, take a fourth pass and check your work.

7. Process of Elimination, Multiple Choice answers

Each question has four multiple choice answers. Thinking from a practical standpoint, there may be some answers that are obviously wrong. Use the multiple choice format to your advantage and look at the answers before you start solving. See if there is anything you can eliminate. Sometimes the wrong answers will also be used to trick you. If you used the wrong equation or forgot to multiply by the factor of safety, your answer may still be among one of the choices. In the same respect, see if there are two answers separated by a factor of 2 or 12 inches per foot, perhaps it should be one of those two. Finally, there is no penalty for wrong answers. So, even narrowing down your answers to a 50/50 chance gives you a much greater advantage.

8. Memorize basic equations

There are a few basic equations that are so commonly used that you should memorize and not waste your time looking up. The more that you can add to this list, the quicker you will become during the test.

9. Know the extents of your calculator

The NCEES has a list of pre-approved calculators that you are allowed to bring into the exam room. Check the NCEES website for the latest version of this list.

• Casio, All fx-115 and fx-991 models

• Hewlett Packard, HP33 and HP 35 models

• Texas Instrument, TI-30X and TI-36X

I would recommend the Casio FX-115ES Plus or the TI-36X Pro models; the TI-36X Pro does have a slightly better visual.

Your calculator should have enough memory to scroll up to previous calculations and answers. Also bring with you the instructions manual of the calculator and practice features that can help you take advantage of the calculator. It is also a very good idea to bring an extra calculator with you as a backup.

10. Create a Cheat Sheet

The next best thing you can do after understanding concepts is creating a cheat sheet for your equations and study material. Not only do cheat sheets help you recognize important concepts and equations, they enhance your speed for the test. On the cheat sheet list the page number and resource of where that equation came from. If there is any background information needed for that equation, you can quickly look back to the source.

Engineering Pro Guides has put together a free cheat sheet on their website. It is well organized, comprehensive, and contains helpful figures for the exam. The best part is that it is an editable file that you can add to and tailor to your needs, which gives you a major head start on your studying. If there is one thing to gain from this article, it should be this cheat sheet.

11. Beam Diagrams

I really like these beam diagrams in Shigley’s. The appendices shows you various beam diagrams and various loadings. It also gives you the corresponding equations. You will most likely have a beam problem on the exam and so having this appendix can almost guarantee getting one problem correct on the exam.

12. Mechanical Components

There are 13 sub-topics under Mechanical Components and 18 questions on Mechanical Components, so you can expect at least one question on each component. When you go through the various components in Shigley’s, Machinery’s Handbook and Engineering Pro Guides, take note of the common equations, tables and terms encountered for each component and add this information to your study binder and cheat sheets. Don’t get too much into the details of each mechanical component, because there will only be one or two questions on each component so the question cannot be too in depth or obscure. In order to be fair, the question has to be on a commonly encountered problem with each component. For example, common problems encountered with pressure vessels are finding the hoop stress in a spherical or cylindrical shaped pressure vessel and less commonly solving for the longitudinal stress.

13. Joints & Fasteners

I really am a fan of having a figure to go along with each equation or concept. I think this is especially important for the Joints & Fasteners section. I think that you should have a figure for each type of stress and joint combination. For example, you should have a figure for a butt joint weld under shear stress, one for a fillet weld under shear stress, another for a bolt under shear stress and another for an adhesive under shear stress and so on and so on for other stresses like tensile stresses, combination of shear and tensile stresses, eccentric shear stresses, etc. Next to each figure you should have the governing equations that you need to solve each type of stress/joint/fastener combination. An example of this is shown below.

14. Conclusion

Each component or principle within each topic has its own concept that you must understand and a formula or two that go with the component or concept. The main thing you should do is ensure that you know how to solve the various types of problems for each component and concept. Examples of components include shafts, couplings, keys, gears, belts, etc. Examples of concepts include bending, buckling, shear, tension, thermal expansion, etc. There are more useful resources for each of these components and concepts that can be found in the Engineering Pro Guides study guide.

Best of luck to everyone taking the exam!!