88153 - Mechanical Actuators P

Learning outcomes

Upon completion of the course, the student possesses basic knowledge of the operation of the main mechanical organs used in machines and the basic tools for machine dynamic and vibratory analysis. In particular, the student knows: the problems related to dissipative effects in kinematic couples; the functional aspects of the main power transmissions and shaft-connecting organs; the main models for studying the dynamics of machines and vibrating systems.

Course contents

1. Dissipative actions in machine components

Kinetic friction and Static friction. Wear: Reye hypothesis; distribution of contact pressure. Rolling friction: applications of rolling contact. Rolling bearings: choice and applications.

2. Functional analysis of power transmissions

Gears: involute profiles; geometrical parameters; cylindrical spur gears and helical gears; force transmission; bevel gears; worm gears. Gear trains: ordinary gears; epicyclic trains; differential trains. Change gears. Transmission of motion between two shafts: belt drives; transmissions with chains.

3. Functional analysis of devices connecting two shafts

Brakes: classification; block brakes; brake torque. Clutches: classification; disk friction clutches; conical friction clutches. Couplers: classification; solid couplings; Oldham’s joint; Hooke's joint; constant velocity joints; flexible joints.

4. Dynamic analysis of machines

Fundamental equation of dynamics: kinetic energy; energy equation. Metodi energetici per lo studio della dinamica di sistemi di corpi rigidi. Dynamics of the slider crank mechanism: calculation; methods for the compensation of inertia actions. Dynamics of the four-bar linkage. Rotor dynamics: static and dynamic imbalance.

5. Mechanical vibrations

Mass-spring-damper model. Free and forced vibration response of one degree-of-freedom system. Free and forced vibration response of two dof systems. Applications: reduction of the force to the ground; reduction of vibrations generated by a vibrating ground; mass damper;

Readings/Bibliography

1. FUNAIOLI E., MAGGIORE A., MENEGHETTI U., Lezioni di Meccanica Applicata alle Macchine. Prima parte: Fondamenti di Meccanica delle Macchine, ed. Pàtron, Bologna.
   
   
2. Callegari M., Fanghella P., Pellicano F., Meccanica Applicata alle Macchine, CittàStudi, 2013
   
   
3. Supplementary materials (diagrams and slides employed during lectures).

Teaching methods

The course is based on lectures dealing with the theoretical aspects of the course topics and application examples.

Class attendance, although not mandatory, plays a fundamental role in the learning and evaluation process.

Assessment methods

The final examination consists of questions that aim to ensure the acquisition of knowledge expected by the course program and to assess the achievement of learning objectives.

Both oral and written questions might be proposed during the examination.

The ability of the student to articulate and correctly explain the answers to the questions, has a fundamental weight in the attribution of the final marks.

In accordance with the Art. 16 of the University Didactic Regulations, if a positive grade does not meet the expectations of a student, the latter may ask its cancellation and the repetition of the examination. The instructors of the course comply with the following rules:

• a student may request the cancellation of a positive grade only within the date of the examination;
• a cancelled positive grade can in no way be recovered;
• a student may request the cancellation of a positive grade at most once.

Teaching tools

Blackboard, PC.

On the E-learning Platform (https://virtuale.unibo.it/ ), students may find: slides of the course lectures; exercises and application examples.

Office hours

See the website of Lorenzo Agostini