The course offers the knowledge on the methods to quantitatively estimate noise radiating from vibrating plates and to passively reduce the noise and includes the modal analysis and forced vibration analysis of plates, the estimation of sound power radiating from the plates based on the vibration analyses, the estimation of sound power transmitting plates excited by sound, and the reduction of sound power with the structural optimization or damping materials.
Because noise radiation from vibrating machinery strongly affects the added value of the machinery, it is expected to reveal the propagation mechanism from vibration to noise and to reduce noise radiating from machinery. As the application of learning of mechanical dynamics in Mechanical Engineering Course, students will understand the energy balance in vibrating plate and the estimation of frequency spectrum of sound radiation power based on the vibration analysis and sound field analysis. Moreover, students will learn the methods to reduce the sound radiation with the structural optimization or damping materials by taking account of cost performance.
By the end of this course, students will be able to:
1. Explain the outline of calculation process to analyze vibration mode and forced vibration of plate
2. Explain the relation between the energy balance in vibrating plate and the sound radiation power
3. Explain the outline of the methods to estimate frequency spectrum of sound power radiating from vibrating plate
4. Explain the structural optimization to reduce noise radiation
5. Explain the principle to reduce vibration with damping materials
Vibration and noise, sound radiation power, modal analysis, forced vibration, parameters to estimate noise, structural optimization to reduce noise radiation, vibration damping
|Intercultural skills||Communication skills||Specialist skills||Critical thinking skills||Practical and/or problem-solving skills|
Important issues are summarized at the end of the class every week. Students are expected to understand what they learn by themselves.
|Course schedule||Required learning|
|Class 1||Modal analysis and forced vibration analysis of plate - Introduction of various methods to theoretically analyze flexural vibration of plate -||Understanding of equation of vibration, modal analysis and forced vibration of plate|
|Class 2||Examples of analysis for various plates - Fixing conditions of plates and the results of modal analysis -||Understanding of mode shape based on node and anti-node|
|Class 3||Formation of sound field due to vibrating source - Point sound source and wave equation -||Understanding of Rayleigh's equation|
|Class 4||Fundamental equations to estimate sound power radiating from vibrating plate - Energy balance in vibrating plate and parameters to estimate sound radiation power -||Understanding of parameters to estimate sound radiation power|
|Class 5||Examples of estimation of sound power radiating from vibrating plate - Estimation of sound power radiating from rectangular plates and circular plates -||Understanding of the relation between frequency spectrum of sound radiation power and natural frequencies of plate|
|Class 6||Structural optimization to reduce sound radiation power - Noise reduction by changing plate thickness or adding ribs or hollows on plates -||Understanding of the objective function and optimization method|
|Class 7||Setting damping materials to reduce sound radiation power - Noise reduction with constraint and non-constraint dampers -||Understanding of damping principle|
Several handouts will be often distributed. The following textbooks are recommended as reference books:
1. W. Weaver Jr., S. Timoshenko and D. H. Young, Vibration Problems in Engineering (Fifth Edition), John Wiley and Sons (1990).
2. K. Suzuki, K. Nishida, K. Maruyama and T. Watanabe, Vibrations and Acoustics for Mechanical Engineering, Saiensu-Sha Co. Ltd. (2000).
Students' knowledge on the process to estimate the frequency spectrum of sound power radiating from vibrating plate based on accurate vibration analysis and sound radiation analysis and the methods to reduce sound power with structural optimization and damping optimization is accessed via submitted reports(100%) on several issues.
Students must have successfully completed 'Mechanical vibration' (MEC.D201) or have equivalent knowledge.
Nobuyuki Iwatsuki: nob[at]mep.titech.ac.jp, 03-5734-2538
Contact by e-mail in advance to schedule an appointment.