The course aims to provide students of the knowledge and understanding of the criteria of structural design of the main mechanical members.
The course aims to provide students of the knowledge and understanding of the criteria of structural design (for static strength, in presence of fatigue, against instability) and of the 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.
Classroom lessons.
1st part – Fundamentals of machine design
Recalls of statics and kinematics of rigid bodies. Tension and strain in solids. Equilibrium of deformable bodies. Loads diagrams. Area of cross sections. Theory of the beams (subjected to tensile, compression, shear, bending, torsion). Effects superposition. Equation of the elastic line. Conventional structural materials (mechanical properties).
2nd part – Criteria of structural design
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.
Notches and their effect. Elastic and experimental stress concentration factor. Safety condition in presence of notches.
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.
Long columns with central loading. Euler column formula.
3rd part – Design of mechanical elements
Connections that cannot be dismantled: Welds. Riveted joints. Glued on joints. Forced connections.
Connections that can be dismantled: Threads. Power screws. Threaded connections. Set screws (outlines). Elements for the motion transmission between co-axial members (outlines): Gib-head keys; Woodruff keys; Pins.
Mechanical springs.
Elements for transmission of power and lifting: Gears. Flexible elements: Belts; Wire ropes; Chains.
Members for storage or transfer of energy associated to rotating motion.
Brakes. Clutches. Flywheels.
Bearings: Rolling contact bearings. Journal bearings.
Axles and shafts: Static design. Dynamic design.
Crankshafts.
4th part – Elements of product design
New approach European Directives (outline).
Standards for the safety of machinery: Machinery Directive and Italian D. Lgs. 81/2008.
Total Design. Product design specification.
Cooperative and Eco-compliant Design.
Design for “X” (specifically: Design for manufacturing and for assembly/disassembly).
Reference books:
De Paulis A., Manfredi E., Costruzione di macchine: Criteri di base e applicazioni principali, Pearson Italia - Milano, 2012
Hibbeler R.C., Meccanica dei solidi e delle strutture: teoria ed applicazioni, Pearson Italia - Milano, 2010
Recommended books:
Vergani L., Meccanica dei materiali, Mc-Graw Hill Companies, 2006
Nerli G., Costruzione di macchine, Noccioli Editore - Firenze, 2005
Shigley J.E., Progetto e costruzione di macchine, 2a ed., McGraw-Hill, 2009
Chirone, E., Tornincasa, S., Disegno tecnico industriale, Ed. Il Capitello - Torino, 2011
Medri G., Cenni di progettazione di prodotto, Liguori Editore, 2008
Ricevimento: The teacher is available for the students at the end of lessons and by appointment
Ricevimento: The teacher is available for the students at the end of each lesson.
MARGHERITA MONTI (President)
ROBERTO RAZZOLI (President)
GIOVANNI BERSELLI
FRANCESCO CRENNA
Written and oral examination. The written test regards the solution of one exercise. The oral examination consists of two questions on theory. A positive evaluation of the written test is necessary condition to access the oral examination.
Suggested pre-requisite: Applied Mechanics, Technical Drawing.
