28661 - Mechanics Applied to Machines T-A

Learning outcomes

Starting from the theoretical foundations of mechanics, the course provides the basic concepts and methods for the functional study of machines, with particular reference to problems related to the use and maintenance

Course contents

Requirements/Prior knowledge

The student who is ready to follow the course knows the vector algebra and the kinematics and dynamics of the material point. Such knowledge is acquired, usually passing the exams of Mathematical Analysis and Geometry&Algebra T-AB (I. C.) and General Physics T-A.

Course Contents

Kinematics pairs. Freedom degrees of fplane and space mechanisms: Grubler and Kutzbach formulas. Basic equations. Analytical static analysis. Graphic static analysis. Examples of graphical static analysis. Mechanical efficiency in direct motion and retrograde motion. Foundations and exercises of graphical static analysis in the absence of friction. Graphic static analysis exercises. Sliding friction. Elementary theory of sliding friction. Limit lubrication. Rolling friction: Hertz theory. Prismatic pair mechanical efficiency. Inclined plane mechanical performance: direct motion and retrograde motion. Mechanical efficiency of rotoidal torque: graphical and analytical calculation. Analytical calculation of mechanical efficiency of helical pair. Wear. Distribution of contact pressure: axial rotoidal pair. Roller and ball rolling bearings: equilibrium moment calculation. Rigid body kinematics in plane motion: graphical determination of instantaneous rotation centers in plane motion mechanisms. Graphic static analysis in presence of friction. Static analysis of the wheels. Graphic static analysis of a tractor. Plane systems kinematics. Graphic kinematic analysis of the four-bar linkage. Graphic kinematic analysis of centered slider-crank mechanism. Exercises. Analytical kinematic analysis of centered slider-crank mechanism and four-bar linkage. Kineto-static analysis of the cam-balancer-valve stem mechanism. Locking equipment. Cylindrical gear wheels: proportionality. Interference between profiles. Analytical static analysis with Principle of virtual works. Transmission ratio of ordinary rotisms. Transmission ratio of epicyclic rotisms. Willis's Formula. Vehicle Differential rotism: operation, relative speeds and transmitted moments. Transmission with flexible organs: fixed and mobile pulley. Rope hoist: choice of pulley, engine and rope; sizing the winding drum and the two-stage epicyclic rotism. Hoist mechanical efficiency. Inertia actions in the motion of a rigid body: special cases. Mechanical characteristic. Examples of force reduction. Hoisting system braking. Replacement masses for dynamic simulation. Inertia actions of centered slider-crank. Rotor Balancing: static and dynamic imbalance. Balancing. Kinetic energy of slider-crank. Dynamics of systems operating at a periodic regime: degree of irregularity and calculation of inertia moment of the flywheel. Free vibrations of damped systems with a degree of freedom. Force vibrations of damped systems with a degree of freedom: motion equation and amplitude and phase diagrams. Vibration isolation: suspended mass excitation. Vibration isolation: excitation of the base. Vibrometer. Design of the suspension of an automatic washing machine.

Readings/Bibliography

E. Funaioli, A. Maggiore, U. Meneghetti, Meccanica applicata alle macchine, Parte Prima: Fondamenti di Meccanica delle Macchine, Ed. Patron, Bologna.

The texts of the classroom exercises are made available by the teacher and tutor of the course on the AMS Campus portal.

Teaching methods

Teaching is provided with frontal lectures conducted by the teacher and exercises proposed and resolved in collaboration with the tutor of the course.

Exercises are projects that reveal the application nature of the analysis and design tools provided by the course.

Assessment methods

Examination will be oral on all subjects taken in the classroom, including exercises.

The questions will cover the three thematic areas of the course: static, kinematics and dynamics.

In order to access to the oral exam, the exercise book must be displayed: it must include the solutions (with data related to the badge number of students) of exercises already taken in the classroom by the teacher.

During the calendar year, 7 ordinary and 2 extraordinary (out-of-course students) examination calls are set in the following periods:

January (ordinary)
February (ordinary)
May (extraordinary for out-of-course students)
June (ordinary)
June / July (ordinary)
July (ordinary)
September (ordinary)
October / November (extraordinary for out-of-course students)
December (Ordinary)

Office hours

See the website of Riccardo Rubini