CODE 65971 ACADEMIC YEAR 2016/2017 CREDITS 9 cfu anno 3 INGEGNERIA MECCANICA 8720 (L-9) - SCIENTIFIC DISCIPLINARY SECTOR ING-IND/14 LANGUAGE Italiano TEACHING LOCATION SEMESTER 1° Semester 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. LEARNING OUTCOMES (FURTHER INFO) 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 ALESSANDRO REBORA Ricevimento: By appointment requested by email Exam Board ALESSANDRO REBORA (President) MARGHERITA MONTI ROBERTO RAZZOLI LESSONS Class schedule MACHINE DESIGN EXAMS EXAM DESCRIPTION Written and oral examination. The written test regards the solution of one or two exercises. The oral examination consists of one or two questions on theory. A positive evaluation of the written test is a necessary condition to access the oral examination. Exam schedule Data appello Orario Luogo Degree type Note 29/03/2017 15:00 GENOVA Orale 09/06/2017 09:00 GENOVA Orale 05/07/2017 09:00 GENOVA Orale 11/09/2017 09:00 GENOVA Orale 25/10/2017 15:00 GENOVA Orale FURTHER INFORMATION Suggested pre-requisite: Mechanics of Solids and Structures. Mechanical drawing.
