B6377 - Mechanical Vibrations

Learning outcomes

The student acquires fundamental knowledge of mechanical vibrations. The students become familiar with the main signal analysis techniques and the associated issues. They understand the principal methods for vibration measurement and the fundamentals of experimental modal analysis. They also acquire knowledge of the main technical solutions for vibration reduction and isolation, aimed at improving onboard comfort.

Course contents

1. Mechanical vibrations.
Fundamentals of mechanical vibrations.
Single Degree of Freedom Systems: free and forced vibrations; resonance; viscous damping; Coulomb damping; hysteretic damping. Two Degrees of Freedom Systems. Multi-degree of Freedom systems. Continuous Systems: mono and bi-dimensional systems. Approximate methods (Rayleigh and Rayleigh-Ritz).

2. Vibration measurements and Signal analysis
Vibration measurement scheme. Vibration transducers. Frequency analysis: Leakage. Data sampling: Aliasing; Shannon's theorem. Discrete Fourier Transform. Definition of acquisition parameters. Auto- and Cross- Spectrum. Frequency Response Function (FRF) and Coherence function.

3. Experimental Modal Analysis (EMA).
Introduction to experimental modal analysis. Impact hammer and shaker. System excitation: random, impulsive, sinusoidal. Procedure outline. Examples.

4. Vibration reduction and isolation for onboard comfort.
Main sources of onboard vibration. Overview of relevant standards. Vibration isolation. Dynamic damper. Solutions for passive vibration control.

Readings/Bibliography

Lecture slides are available on https://virtuale.unibo.it/.
1. Rao S.S., Mechanical vibrations, Sixth edition, Pearson Education, 2018.
2. Inman D.J., Engineering Vibration, 4th edition, Pearson Education, 2014.

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 exam is oral and includes questions aimed at verifying the acquisition of the knowledge outlined in the course syllabus and at assessing the achievement of the learning objectives.

In accordance with Art. 16 of the current University Didactic Regulations, a negative assessment does not result in the assignment of a grade. In the case of a positive outcome, the grade may be declined only 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 Alessandro Rivola