This Thesis is about the application of Statistical Energy Analysis (SEA) to the study of noise and vibration in motor vehicles. Methods for predicting the transmission of structural waves between body panels in motor cars are given. A complex joint technique based on the wave dynamic stiffness approach is discussed in detail. This technique can account for the complexities of the joint structures found in motor vehicles. Transmission of vibration energy between panels connected by a curved section of panel has been investigated using the complex joint modelling technique. Wave Intensity Analysis(WIA) and SEA were used to calculate the coupled panel vibration levels based on transmission coefficients calculated using the complex joint techniques. Energy Level Differences (ELDs) were measured for comparison with predicted results using laboratory models. SEA failed to accurately predict the ELDs except at low frequencies. However WIA was able to predicted the ELDs with reasonable accuracy using an existing expression for transmission at a panel corner joint. Two SEA models of a small passenger car have also been constructed. One assumes simpler joint configurations when calculating transmission coefficients and the other uses the complex joint technique. Panel ELDs were measured using a small passenger car. The SEA model using the complex joint method gives better agreement with measured ELDs than did the model using the simpler joints. saloon Sound Pressure Level (SPL) as a result of engine noise was measured. Both SEA models of the vehicle gave good agreement between measured and predicted Saloon SPL. A noise problem associated with exhaust misalignment is also investigated.

No description available.

Many space vehicles have been launched with large flexible components such as booms and solar panels. These large space structures (LSSs) have the potential to make attitude control unstable due to their lightly damped vibration. These vibrations can be controlled using a collection of control moment gyros (CMGs). CMGs consist of a spinning wheel in gimbals and produce a torque when the orientation of the wheel is changed. This study investigates the optimal distribution of these CMGs on LSSs for vibration suppression. The investigation considers a beam and a plate structure with evenly placed CMGs. The optimization allocates the amount of stored angular momentum possessed by these CMGs according to a cost function dependent on how quickly vibration motions are damped and how much control effort is exerted. The optimization results are presented and their effect on the motions of the beam and plate are investigated.

Many space vehicles have been launched with large flexible components such as booms and solar panels. These large space structures (LSSs) have the potential to make attitude control unstable due to their lightly damped vibration. These vibrations can be controlled using a collection of control moment gyros (CMGs). CMGs consist of a spinning wheel in gimbals and produce a torque when the orientation of the wheel is changed. This study investigates the optimal distribution of these CMGs on LSSs for vibration suppression. The investigation considers a beam and a plate structure with evenly placed CMGs. The optimization allocates the amount of stored angular momentum possessed by these CMGs according to a cost function dependent on how quickly vibration motions are damped and how much control effort is exerted. The optimization results are presented and their effect on the motions of the beam and plate are investigated.

No description available.

No description available.

Thesis (MAppSc in Applied Physiotherapy)--University of South Australia, 1994

This research focuses on investigating the vibration characteristics of branched circular cylindrical shells with applications to airway passages. Analytical modelling is carried out based on Donnell-Mushtari equations of thin elastic membrane type of shells while numerical validation is conducted using the Finite Element Method (COSMOS/Works). Further validation of the results is performed using experimental investigation of tracheobronchial tissues dissected from pigs. The analytical, numerical and experimental results are in acceptable agreement. Further investigation of the vibration characteristics of the airways for cases which cannot be dealt with analytically is carried out using COSMOS/Works. Results show a strong trend relationship which suggests that the natural frequency of the trachea and the primary tracheobronchi is approximately 10 Hz. Radial resonances of lower bronchi are predictable through trends found in this work that the resonant frequency is a linear function in certain region of generations.

Research Doctorate - Doctor of Philosophy (PhD) / Mechanical structures encounter vibration in response to environmental conditions and dynamic loads. In most circumstances, vibration contributes to mechanical fatigue which can eventually lead to catastrophic failure. Consequently, vibration control is a necessity for prolonging the operational life of structures. Piezoelectric and electromagnetic transducers have been used for control of vibration for many years. They normally sense mechanical vibration and generate an opposing vibration through another piezoelectric and electromagnetic transducer. This is usually referred to as active feedback vibration control. Another vibration control strategy senses and actuates simultaneously through an appropriately designed electrical impedance which is connected to the terminals of a single transducer. This technique requires no additional sensor, has improved robustness and stability, and a similar feedback structure compared to active feedback vibration control. The objective of this thesis is to develop new vibration control techniques by expanding on both the previously mentioned strategies. The first part of this thesis considers connecting an electrical impedance to a piezoelectric transducer to control vibration. This part reinforces that this vibration control strategy can be modelled as a variation of active feedback vibration control whereby the impedance parameterises the effective controller. A series of new vibration controllers are then presented. Applying the knowledge gained in the first part of this thesis, the second part considers replacing the piezoelectric transducer with an electromagnetic transducer. Although the underlying dynamics and physical properties of the transducers are different, the feedback structures are remarkably similar to that of active feedback vibration control. A number of new vibration control strategies are proposed for a variety of mechanical systems. Throughout the thesis, theoretical ideas and concepts are experimentally compared and validated on simple mechanical apparatuses to evaluate their vibration control performance.

Thesis (Ph. D.)--University of Akron, Dept. of Chemistry, 2007. / "December, 2007." Title from electronic dissertation title page (viewed 03/19/2008). Advisor, David S. Perry; Committee members, Edward C. Lim, David Modarelli, Jutta Luettmer-Strathmann, Steven S. Chuang; Department Chair, Kim C. Calvo; Dean of the College, Ronald Levant; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.