AIMS AND CONTENT

LEARNING OUTCOMES

The course aims to provide students with tools and criteria for structural analysis and design (design for static strength, in presence of creep, against brittle fracture, in presence of fatigue, against instability) and with methodologies and instruments for the analysis and structural design of the main mechanical members.

Furthermore the course aims to introduce students in methods that allow the engineer to go from idea to executive design of an industrial product,  to provide the knowledge required for classification, representation and choice of standard components and to explain the basics of the product-oriented design.

AIMS AND LEARNING OUTCOMES

The course aims to provide students with knowledge and understanding of the criteria of structural design (for static strength, in presence of creep, against brittle fracture, in presence of fatigue, against instability) and with methodologies and instruments for the analysis and structural design of the main mechanical members.

Furthermore the course aims to introduce students to product design, with particular reference to the design process and to design for safety, for manufacturability, for cost, for assembly and for environment.

TEACHING METHODS

Lectures and practice integrated with lectures.

SYLLABUS/CONTENT

1st part – Fundamentals of machine design

Mechanics of solids and structures

Stresses and strains in solids (recalls). Principal stresses (recalls). Special problems of solid mechanics. Plane strain and plane stress problems. Special problems of structural mechanics. Beam theory (recalls). Curved members in flexure. Membrane theory for thin axisymmetric cylindrical and spherical shells. Contact stresses.

2nd part – Criteria of structural design

Static strength

Static strength of materials. Ideal or equivalent stress. Strength criteria for ductile materials. Strength criteria for brittle materials. Safety condition: Limit stress, Safety factor, Admissible stress, Safety margin (grade). Notches and their effect. Elastic and experimental stress concentration factor. Safety condition in presence of notches.

Fatigue

Fatigue in metallic materials. Fatigue spectra. High cycle fatigue: Wöhler curves; Influence of the mean stress; Notches and their influence; Size factor; Surface factor. Safety condition for stresses of constant amplitude. Safety condition for stresses of variable amplitude: Cumulative damage.

Brittle fracture

Brittle fracture in presence of cracks. Linear elastic fracture mechanics  (LEFM): Stress intensification factor; Plastic zone at the crack tip; Fracture toughness. Safety condition according to LEMF criteria. Crack propagation by fatigue (outline).

Creep

Creep in metallic materials. Creep tests. Larson Miller parameter. Safety condition in presence of creep.

Long columns with central loading

Euler column formulas.  The “ k “ method.

3rd part – Design of mechanical elements

Vessels and pipes
Cylindrical vessels and pipes. Spherical vessels. Vessels for high pressures.
Rotating disks
Disks of constant thickness. Disk with crown and hub.
Connections that cannot be dismantled
Weldings. Riveted joints. Glued on joints. Forced connections.
Connections that can be dismantled
Threads. Power screws. Threaded connections. Set screws (outlines). Elements for transmitting motion between co-axial members (outlines): Gib-head keys; Woodruff keys; Pins.

Elastic connections

Mechanical springs.

Elements for power transmission and lifting

Gears. Flexible elements (outlines): Belts; Wire ropes; Chains.

Members for storage or transfer of energy associated to rotating motion (outlines)

Brakes. Clutches. Flywheels.

Bearings
Rolling contact bearings. Principles of hydrodynamic lubrication (outlines); Journal bearings.
Axles and shafts
Static design. Dynamic design.
Members for the motion transformation
Crankshafts. Connecting rods.

4th part – Elements of product design

Design process.

Design for safety; Design for manufacturability; Design for cost; Design for assembly; Design for environment.

RECOMMENDED READING/BIBLIOGRAPHY

Teacher’s lecture notes.

Reference books:

De Paulis A., Manfredi E., Costruzione di macchine, Pearson Italia, Milano, 2012

Chirone, E., Tornincasa, S., Disegno tecnico industriale, Ed. Il Capitello - Torino, 2011

Medri G., Cenni di progettazione di prodotto, Liguori Editore, 2008

TEACHERS AND EXAM BOARD

Exam Board

MASSIMILIANO AVALLE (President)

MATTIA FRASCIO

FLAVIA LIBONATI

ALESSANDRO REBORA

MARGHERITA MONTI (President Substitute)

LESSONS

LESSONS START

https://corsi.unige.it/8720/p/studenti-orario

Class schedule

The timetable for this course is available here: Portale EasyAcademy

EXAMS

EXAM DESCRIPTION

The exam is a written test consisting in the solution of 1-2 problems of design of a mechanical system (including the selection or sizing of some mechanical parts/components, practice) and 1-2 open questions on the topics illustrated during the lecture (theory). Each part of the written test can give a score up to 15/30 points, for a maximum total of 30/30. Both tests must be passed with a sufficient score (minimum 9/15 for both).

To the score obtained from the written test, the result of the evaluation of the homework project will be added. The homework project could be evaluated in the range ±3 points (there can be a penalty for a poor project).

If the global score, sum of the results of the written test and homework project, will be greater or equal to 32 points, an evaluation of 30 cum laude can be attributed and registered. 

Students with SLD, with disabilities, or with other regularly certified special educational needs will agree with the teacher on the exam method and the compensatory instruments, by contacting the instructor at least 10 days before the exam. They will also be able to take advantage of the additional time required by law.

ASSESSMENT METHODS

The proposed exercices are aimed at evaluating the capacity in solving problems ot mechanics of structures applied to mechanical components.

The questions are aimed to checl the capacity to describe the understanding of the problems of machine design and of the physical meaning of the studied problems.

Exam schedule

FURTHER INFORMATION

Suggested pre-requisite:

• Mechanics of Solids and Structures.
• Mechanical drawing.