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Acoustics Engineering Lab II

Description
In order to do important predictions of the structures´ vibro-acoustic behavior such as automobiles, railways, spacecrafts or buildings, or to make sound predictions of vehicle or railways traffic, acoustic engineers need simulation tools. During the first semester of the subject Theory and laboratory of Acoustic Engineering I we´ll study the fundaments of the most used numeric methods in vibrocoustics. We focus on the finite element method (FEM) that is used for low frequency problems and in the statistic energetic analysis that is used for high frequencies. We´ll also have a brief introduction to the boundary element method (BEM) and acoustic geometry (rays theory). The second semester of Theory and laboratory of acoustic engineering II is completely practice and it is coursed in the following year, when the future engineer had acquired all the Acoustics practical knowledge. The 5 guided practices cover a wide range of ambits and guarantee the achievement of abilities and competences to use acoustic instruments (microphones, loudspeakers, analyzers, etc.) During the subject, the theoretical concepts studied during the first semester and the Architectonic Acoustics subject, are consolidated guaranteeing the necessary competence theoretical-practical to access the labour market.
Type Subject
Tercer - Obligatoria
Semester
Second
Course
4
Credits
3.00

Titular Professors

Previous Knowledge

Theory and laboratory acoustic engineering I.

Objectives
Contents

1st SEMESTER: DETERMINISTIC AND STATISTIC NUMERICAL METHODS [~45h]
1. Introduction to acoustic analytics [6h]
1.1. Conservation equations of continuum mechanics
1.2. Wave equation and Helmholtz equation
1.3. The Green function in free space
1.4. Monopoles, dipoles and quadripoles
1.5. Noise generated by the distribution of acoustic sources in presence of arbitrary surfaces
1.6. Noise generated by a plate.
1.7. Summary

2. Finite elements (FEM) and boundary elements (BEM) [20h]
2.1. Introduction
2.2. One-dimensional model problem
2.3. Week formulation
2.4. Discretization of the week formulation: the finite elements method
2.5. Estimation of the FEM error
2.6. Example In two dimensions: the Helmholtz equation
2.7. Computational and programming aspects
2.8. Boundary element method

3. Statistic Energetic Analysis (SEA) [19h]
3.1. Introduction
3.2. Model problem
3.3. Consistence relation
3.4. SEA systems and subsystems
3.5. Energy and modals density
3.6. Loss factors by dissipation, connection and totals
3.7. General equations: matrix method and transmission channel analysis

2nd SEMESTER. LABORATORY: PRACTICES [~45h]
4. P1: Environmental acoustics
- Introduction to sound level meter BK2250 and SC310
- Environmental measurements
- Sound level meter index and operate with its data
- Evaluation according to the Law 16/2002 of Protection against the acoustic contamination

5. P2: Sound power of a source
- Introduction to a calibrated source BK4205, consolidation of the two-channel analyzer BK2034
- Measurement for the sound power according UNE-EN ISO 3745

6. P3: Soundproofing measurements for air and impacts noise.

6.1. Soundproofing measurement for the air noise
- Introduction to the dodecahedron source FP121
- Multi-channel NetdB analyzer use consolidation
- Soundproofing measurement protocol for the air noise according to the UNE-EN ISO 140-4 regulation and the results evaluation according to the UNE-EN ISO 717-1
- Acoustic leakage

6.2 Soundproofing measurement for impact noise
- Introduction to the impact machine MI005
- Soundproofing measurements protocols for impact noises according to the UNE-EN ISO 140-7 regulation and evaluation according to UNE-EN ISO 717-2
- Determination of the noise´s origin: impact or air.

7. P4: Time Delay Spectrometry
- Echogram and ETC, reflection localization and combfilter
- Time Delay Spectrometry
- Temporal, spatial and frequency resolution
- Frequency response of a system in non-anechoic environments
- Reverberation time measurement by the Schroeder integration method
- Basic enclosure´s acoustic parameters: RT, %ALCONS and STI/RASTI

8. P5: Enclosure´s own modes. Kundt´s tube absorption
8.1. Enclosure´s own modes
- Introduction to the sound level meter SC30
- Excitation and localization of an enclosure´s own modes
- Schroeder´s frequency measurements

8.2. Acoustic absorption coefficient in a regular incidence
- Measurement of a tube´s frequency resonance
- Measurement of a regular incidence´s absorption coefficient in Kundt´s tube, stationary wave relation

Methodology

1st semester

1. Magisterial classes
2. Problem classes
3. Laboratory demonstration classes (at least 2 during the course)
4. Group practices

2nd semester
Through the semester, the students do 5 practices in groups. The first day of the practice the professor explains the objectives and the basic concepts. Through the experimentation, students solve the exercises and experiments proposed. The second day of the practice, the professor will ask some questions to his pupils to make sure that they have understand the continents.

Between the two days of the practices, students may go to the laboratory to finish the proposed exercises.

Evaluation

1st Semester

Written exams at the end of the second semester (2~3h)
Continuous evaluation based on exercises and practices solved individually or in group (two additional notes to the exam each semester)

2nd Semester

The evaluation is made from an individual practical exam, a theoretical exam and the questions asked at the end of the practices.

The global grade is calculated with as explained below:

Practical exam = 70%
Practical questions = 30%

The final exam is averaged if the Practical Exam grade is ≥ 3.5

2nd semester final grade = 0.70 Practical Exam + 0.30 Questions

The previous formula will only apply if the continuous evaluation (questions) doesn´t affect the course´s final grade.

The attendance to the practice is obligatory. The practical sessions are 3 hours long and each practice has two sessions.
The students have a timetable to access the laboratory after class hours.
Practices are carried out in groups. Depending on the number of students, the groups may be formed by maximum three persons. Students must bring printed and read the practice statement corresponding to that week.

Subject evaluation

The evaluation of each semester is independent. The subject is passed if the Final Grade is equal to or higher than 5.

Final Grade = 0.50 Final Grade 1st Semester + 0.50 Final Grade 2nd Semester

The previous medium value will be only applied in the event that the grades of each semester are higher or equal than 4,5.

In the event that only one semester is passed, the grade will be keep for the next semester, but not for the following.

Evaluation Criteria
Basic Bibliography
Additional Material

Semestre 1
Tema 1:
- M.S. Howe, Theory of Vortex Sound (Cambridge Texts in Applied Mathematics, Cambridge University Press) (2003)
- D. Crighton, P. Dowling, J.E. Ffowcs Williams, M. Heckl and F. Leppington, Modern Methods in Analytical Acoustics (Springer-Verlag) (1992)
- P. M. Morse and K. U. Ingard, Theoretical Acoustics (First Princeton University Press edition) (1986)
- S.W. Rienstra and A. Hirschberg, An Introduction to Acoustics (Eindhoven University of Technology) (2004)

Tema 2:
- T.J.R. Hughes, The Finite Element Method. Linear Static and Dnamic Finite Element Analysis, Dower (2000)
- C. Johnson, Numerical solutions of partial differential equations by the finite element method , Cambridge University Press (1987)
- G.C. Cohen, High-Order Numerical Mehods for Transient Wave Equations, Springer (2002)
- Boundary Element Acoustics, Ed. T.W. Wu WIT Press (2000)

Tema 3:
- R.H. Lyon, Statistical Energy Analysis of dynamical systems: theory and applications, The MIT Press (1975)
- R.H. Lyon and R.G. DeJong, Theory and Application of Statistical Energy Analysis, Butterworth-Heinemann (1995)
- R. Craik, Sound Transmission Through Buildings Using Statistical Energy Analysis, Gower, London (1996)
- Statistical Energy Analysis. An overview with applications in Structural Dynamics, Eds. A. Keane and F. Fahy, Cambridge University Press (1997)

Semestre 2
- C.M. Harris and Crede, Shock & Vibration Handbook, Ed. McGraw-Hill, 1988.
- L. Beranek, L. Vér. Noise and Vibration Control Engineering, Ed. John Wiley & Sons, 1992.
- C. Hopkins, Sound Insulation, Ed. BH, 2007
- M.J. Crocker. Handbook of noise and vibration control. Ed. John Wiley & Sons, 2007