Learning objectives
On the basis of a deep knowledge of kinematics, statics and dynamics of mechanical system, the course provides the practical and theorical knowledge required for a proper functional design of machines and their devices
Prerequisites
Mechanical Drawing, Rational Mechanics
Course unit content
Mechanisms assembly Forces acting on mechanisms Efficiency Fundamental concepts of tribology: friction, wearing, lubrication Joints, brakes, clutches Concepts of rigid body kinematics and applications to mechanisms Articulated systems Cam-follower devices Analysis and synthesis of mechanisms Motion transmission between shafts Belt and chain transmissions Gears Fundamentals of dynamics. Mechanism dynamics. Vibrations of one degree-of-freedom systems. Introduction to the experimental investigation. Rotor dynamics.
Full programme
Historical background
Degrees of freedom, Gruebler and Kutzbach formulas
Friction: static and dynamic; cases of friction in prismatic joints, revolute joints, clutches and brakes, inclined plane, screws; rolling friction; case of driving or braking wheels; examples with vehicles; efficiency; series and parallel machines;
Lubrication: newtonian fluids, mass conservation, constitutive laws, viscosity and measuring units, Reynolds equation in 2D and 3D, elastohydrodynamics, applications to: linear bearings, revolute bearings, number of Sommerfeld, fluidostatic lubrication: case of axial and revolute bearing.
Kinematics: Galileo theorem, center of instantaneous rotation, trajectories, primitives and polars, Euler-Savary theorem, conjugate profiles, circle of flexes, Rivals theorem, applications.
Srticulated systems: analysis and synthesis, four- and six-bar linkages, slider cranks, Roberts theorem, Oldham joint, Cardano joint, details on other joints (Rzeppa, Birfield, tripod).
Cam-follower mechanisms and motion profiles.
Gears: friction wheels, involute, rack-pinion, spur gears, bevel gears, features and definitions, corrections, helicoidal gears, Tredgold method, screw gears.
Planetary gears: Willis formula, differentials, automotive gears.
Flexible parts: pulleys, belt transmissions, belt brakes
Principles of rigid body dynamics, constrained dynamics, Lagrange equations.
Dynamics of slider-cranks, equivalent masses in rods, balance of 2,3,4,6,8,12 cylinder engines.
Periodic regime: main formulas for flywheel sizing.
Vibrations for 1 degree of freedom systems. Free, damped, forced; frequency response, transmissibility, sunspensions.
Balance of high-speed rotors.
Numerical methods for equations of motion.
Torque curves, longitudinal dynamics of vehicles.
Bibliography
E. FUNAIOLI, A.MAGGIORE, U.MENEGHETTI: “Lezioni di Meccanica Applicata alle Macchine”, Voll.1-2, Patron Editore, Bologna. For the activities: notes written by the teacher. Other books will be suggested during the lessons.
Teaching methods
Lessons and exercises with applied examples of topics which are discussed at the lessons.
Assessment methods and criteria
The exam consists in an oral examination about topics teached during the lessons.
