The aim of the course is to provide the skills and knowledge necessary for the design and verification of mechanical elements, using both traditional and numerical methods and to produce 2D and 3D CAD models and drawings of components and mechanical systems with particular reference to the problems of dimensional and geometric tolerances.
The topics covered are:
- Integration of structural mechanics (residual stress, variable amplitude fatigue and basic multi-axial fatigue;
- principles and procedures for design and verification of some of the major elements of machines and joints (axes and shafts, axial symmetric solids, hub-shaft connections, bearings, springs, threaded fasteners and bolts, welded joints).;
- principles and rules of dimensional and geometric tolerancing, criteria for their control and methods for stack-up analysis;
- methods for functional representation and simulation of industrial projects
- matrix structural analysis (linear elastic static problems)
- basics of finite element method, with particular reference to the obtained approximations.

Knowledge and understanding of mechanical design principles and specific design methodologies for some elements of machines and mechanical joints on the basis of the principal standards.
Knowledge of methods of functional representation and simulation of industrial projects;
Knowledge of geometric and dimensional tolerancing (GD & T) and of the stack-up problems
Knowledge of the theory of matrix structural analysis with static loads
Knowledge of basic principles of finite element method in linear elastic field for the solution of static problems, with particular reference to the obtained approximations.
Ability to perform the design and verification of mechanical elements and connections (axes and shafts, axisymmetric solids, hub-shaft connections, bearings, springs, threaded fasteners and bolts, welded joints).
Ability to produce manual sketch drawing 2D, computer assisted 3D model and drawing with functional dimensioning by using dimensional and geometric tolerancing in stack ups.
Ability to use a FEM code for static linear elastic structural analysis.

Knowledge of mechanical engineering drawing according Standards ISO ' ANSI. Ability to interpret drawings of details and assembly. Experience with software CAD 3D
Ability to carry out the kinematic analysis of simple mechanisms, the ability to perform the calculation of stresses in simple mechanical components, to perform static and fatigue verifications, knowledge of the main thermal treatments.

This course is organized in two parts. Lectures will give a straight presentation of relevant topics to be studied to perform design of machines through verification of the components and of the system. Practice hours will be offered to solve examples, numerical exercises and practical cases, practice with machine design and tools, and an exam simulation.
Topics dealt with in this course are herein listed.

• Machine Design
o Fatigue: stress concentration, basic concepts, engineering fatigue diagrams, fatigue life and fatigue strength influencing factors, multiaxial loading, components safety (9 hours)
o Spindles and shafts: stress states, computation and verification methods (3 hours)
o Gearing: basics, tooth geometry, force calculation, determination of stress loading (6 hours)
o Shaft-hub connections: stress field in axisymmetric solids, tubes and pressure vessels, press fitting, connections by keys, splines, pins, etc. (9 hours)
o Bearings: types, catalogue selection, endurance evaluation, mounting solutions (9 hours)
o Joint and clutches: main connection methods, permanent and moveable (3 hours)
o Threaded connections: description and standards, interference diagrams, stresses in the threaded connectors, effect of external loading, anti-loosing methods, fatigue strength (6 hours)
o Welding: processes and methods, types of welding, verification with Eurocodes, variable loading (3 hours)
o Springs: types of springs, applications, utilization factor, springs in series and in parallel, torsion springs, leaf springs, static and fatigue verification (6 hours)

• CAD
o CAX environment (context: objects, models, representations, computer graphids, modeling, image processing, pattern recognition) (1.5 hours)
o Part specification (part specification: type, comprehension; types: raw, finished for SW and NX) (1.5 hours)
o Product & Process development: PDM & DMU (1.5 hours)
o Modeling overview: Feature Based and Geometric modeling (models, propotypes vs. drawings, solid modeling, feature base models, sketching, parametric modeling) (1.5 hours)
o 2D GD&T overview and drawing procedure (2D drawings, dimensioning, geometric tolerancing)
o 3D curve & surface modeling (curves, cubic, splines, Bézier, B-spline, NURBS) (1.5 hours)
o Modeling summary (synthesis of rigid parts modeling, solid surfaces integration) (1.5 hours)
o Overview of graphic hardware & software (vector vs. raster, input & output devices) (1.5 hours)
o Overview of CAM, rapid prototyping & reverse engineering(1.5 hours)
o Data exchange overview (automotive application, databases) (1.5 hours)
o CAD evolution (FB evolution, paradigm concept) (1.5 hours)

Practice is divided into three parts:
• Assisted exercises on the topics of machine design: to apply the fundamental skills described in the various lectures
• Applied CAD laboratory: the drawing skills and technique will be applied to generate models of a series of mechanical systems. Outcome of this practice work will have to be delivered before the end of the course period (end of the lectures): failure to comply with this deadline will prevent participation to the exams.
• Homework project: development of a mechanical system project. A simple mechanical system (usually a transmission line for speed reduction) will be completely designed in all its parts and assembly. All the various parts (gears, shafts, supports, connections, etc.) will be subject to verification for strength, in static loading and fatigue, to insure an adequate level of safety against failure. The system will be drafted together with the details of the parts that compose the system. This homework project will be developed in team-working, by teams of at least 2 students and a maximum of 3 students. Teams of 2 students are preferred. Each student shall contribute equally to the development of the project, and will be equally responsible for the quality and validity results. The main fulfillment of this homework project will be the preparation of a written report of the design flow and of all the calculations and verifications made. The report, possibly printed or written in high quality standard, will include the tables with drawings of the system parts. Drawings shall be conforming to current technical standards, either Italian, European, or International. The report shall be delivered before the end of the course period (end of the lectures): failure to comply with this deadline will prevent participation to the exams. Delivery will be fulfilled in electronic form according to specifications that will be detailed during the course. The report will be evaluated and rated for what concern the design and drawing contents: rating is indicated in the following, in the section dedicated to the exams rules. A minimum acceptable quality of both design calculations and drawings is strictly requested. The teachers will evaluate the outcome of the homework projects, and can reject it: in this case the exam will not be recorded, even in the case of a positive result, until an acceptable report is resent and rated.

Material used by the teachers during the lectures, and distributed through the university portal.
Notes directly taken from the classes will be shared with students through the website.
Electronic resources that can be found in the internet will be also suggested.

Main study references:
• Budynas, R., Nisbett, J., Shigley’s Mechanical Engineering Design, 8th Edition in SI units, McGraw Hill, 2008
• Juvinall, R.C., Marshek, K.M., Fundamentals of machine component design, 4th Edition, Wiley, 2006
• Childs, P.R.N., Mechanical Design, 2nd Edition, Elsevier, 2004 (also in eBook format, see library website)
• Rossetto, M., Introduzione alla fatica dei materiali e dei componenti, Levrotto & Bella, Torino, 2000
• Goglio, L., Resistenza dei Materiali e dei Collegamenti, Levrotto & Bella, Torino, 2006
• Collins, J.A., Failure of Materials in Mechanical Design, 2nd Edition, Wiley, 1993

Additional textbooks:
• Suresh, S., Fatigue of materials, Cambridge University Press, 1998
• Niemann, G., Winter, H., Maschinenelemente, 2nd Edition, Springer, 1983
• Niemann, G., Winter, H., Elementi di Macchine, Edizioni di Scienza e Tecnica, 1986
• Niemann, G., Winter, H., Höhn, B., Manuale degli organi delle macchine, Tecniche Nuove, Milano, 2006
• Giovannozzi, R., Costruzione di Macchine, vol. 1 & 2, Patron, 1980 (historical)
• Pighini, U., Elementi Costruttivi delle Macchine, Edizioni Scientifiche Associate, 1980 (historical)
• Strozzi, R., Lezioni di Costruzione di Macchine, Pitagora, Bologna, 1998
• Riccadonna, A., Todeschini, M., Disegno, progettazione e tecniche di produzione, Hoepli, 2008.
• Straneo, Consorti, Disegno, progettazione e organizzazione industriale, Vol. I, II, III, Principato
• Moos, S., Vezzetti, E., Tornincasa, S., Zompì, A., Quotatura funzionale degli organi di macchine, CLUT

Final exam consists of two parts, written and practical.
The 2 parts must be passed within the same session of exams, in the dates and classrooms indicated in the educational portal.
Admission to the practical examination will be subject to a valid score in the written parts.
To be admitted to any part of the exam, it is required to have and to show a valid identification card or the personal university card with a clearly readable photograph. In absence of this evidence the candidate will be rejected and the attendance to the test forbidden.
The use of any electronic digital device (phones, smartphones, tablets, computers, etc.) except calculators (even programmable, but without any operating system) is strictly forbidden. The use of any of these digital electronic devices will be subjected to cancellation of the test and expulsion from the examination room.
Only the material provided by the teachers and their assistants can be used, except for paper, pens and pencils, rubbers and correctors, rulers and other measuring and drawing aids, calculators. The use of any types of written or typed papers, books or handbooks is not admitted and is a reason for immediately excluding the student from the examination. All the material distributed by the teachers and their assistants shall be entirely returned. Failing to return the material will exclude from the examination.
It is not permitted to communicate in any form with other students or with any other person except the teachers and their assistants. Any transgression will be subjected to expulsion and exclusion from the exam.
Admission to the exams follows registration to the call in the dates indicated in the portal.
The student has 15 minutes from the start of any written test to withdraw: after this time the exam will be recorded as failed. In the case of withdraw also, all the given material shall be entirely returned.

• Written Part: at the end of all the classes, the student will be required to attend a written test, divided in three parts:
o 15 closed questions on general topics of machine design with 3 answers each: each valid answer scores +1 point; a wrong answer scores -0.5 points; a missing answer scores 0 points. Time: 45 minutes. While the student will have this first part completed and delivered, he shall wait until the end of the given time.
o 1 exercise (or 2 simpler exercises) of machine design to be numerically solved; exercises will be like the ones solved during practice. Correct numerical results are mandatory: development of the calculations is not sufficient for a positive outcome, as well as erroneous numerical results. Time: 45 minutes.
o 10 questions (closed and open answer questions, calculations, and drawings) on the CAD topics to evaluate the student’s theoretical knowledge. Time: 30 minutes.

• Practical Part (laboratory test): Aims at evaluating the student’s operational ability. The test will be as follows:

o Input
1. 2D assembly drawing of a mechanical system
2. A 2D drawing of one part of the system
3. All the remaining 3D part models of the system
4. The part of the system to be represented on a 2D GD&T drawing

o Process
- Understand how the system works
- Model the part Input 2
- Assemble all the parts in a working system
- Make the 2D GD&T drawing of the Input 4

o Output
- 3D model of the part Input 2
- 3D assembly of the system
- 2D GD&T drawing of the part Input 4

If both tests will be evaluated sufficient, final score will be computed as a weighted average between the marks of the two parts of the exams, plus additional points from the evaluated homework project: an acceptable but very bad project outcome can result in a negative evaluation (negative score). To complete the exam student has to pass both tests.

THE FINAL SCORE WILL BE DETERMINED AS FOLLOWS:

1) Written test
- MD Questions (15, in 45’) = max 15/40
- CAD questions (10, in 30’) = max 10/40
- Exercises (1 or 2, in 45’) = max 15/40
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Total written test score (MD + CAD + Exercises) = max 40/40 (= A)

2) Practical test
- CAD = max 30/30 (= B)

3) Technical report and drawings = max 3 points (= C)

Final score = 1/2 A + 1/3 B + C