Techn. University, Diss., 2004--Dresden.

No description available.

No description available.

This thesis deals with a systematic procedure for the derivation of exact expression for the frequency equation of composite beams undergoing forced vibration with damping. The governing differential equations of motion of the composite beam are derived analytically for bending and shear deformation. The basic equations of Timoshenko beam theory and assumption of maximum rate of dissipation are employed. The principle involved is that of vibration energy dissipation due to damping as a result of deformation of materials in sandwich beam. The boundary conditions for displacements and forces for the cantilever beam are imposed and the frequency equation is obtained. The expressions for the amplitude of displacements are also derived in explicit analytical form. Numerical results of the displacement amplitude in cantilever sandwich beam varying with damping coefficient are evaluated.

The flow field behavior in the vicinity of a perforated breakwater and the efficiency of the breakwater under regular waves were studied. To examine the efficiency of the structure thirteen types of regular wave conditions with wave periods T = 1, 1.2, 1.6, 2, 2.5 sec and wave heights Hi = 2, 4, 6, 8, 10 cm in an intermediate water depth of 50 cm were tested. The incoming, reflected and transmitted wave heights were measured using resistance type wave gauges positioned at the required locations. The efficiency of the structure was calculated considering the energy balance for the system. The efficiency of the structure for different wave conditions and with different parameters are shown and compared. Seven types of regular waves with wave periods T = 1, 1.6, 2, 2.5 sec and wave heights Hi = 4, 6, 8, 10 cm in an intermediate water depth of 50 cm were tested for the flow behavior study. In order to study the flow field variation with phase, ten phases were considered per one wave. The Particle Image Velocimetry (PIV) technique was employed to measure the two dimensional instantaneous velocity field distribution and MPIV (Matlab toolbox for PIV) and DaVis (a commercial software) were used to calculate the velocity vectors. By repeating the experiments and taking an average, the mean velocity field, mean vorticity field, mean turbulent intensity and mean turbulent kinetic energy field were calculated for each phase and for each wave condition. The phase average fields for each wave condition for each of the above mentioned parameters were calculated taking the average of ten phases. The phase averaged velocity, vorticity and turbulent kinetic energy fields are presented and compared. The energy dissipation based on both elevation data and the velocity data are presented and compared. It was found that for more than 75% of the tested wave conditions, the energy dissipation was above 69%. Thus the structure is very effective in energy dissipation. Further it was found that for all the tested wave conditions most of the turbulent kinetic energy form near the free surface and near the front wall, where as behind the back wall of the structure the turbulent kinetic energy was very small.

This thesis deals with a systematic procedure for the derivation of exact expression for the frequency equation of composite beams undergoing forced vibration with damping. The governing differential equations of motion of the composite beam are derived analytically for bending and shear deformation. The basic equations of Timoshenko beam theory and assumption of maximum rate of dissipation are employed. The principle involved is that of vibration energy dissipation due to damping as a result of deformation of materials in sandwich beam. The boundary conditions for displacements and forces for the cantilever beam are imposed and the frequency equation is obtained. The expressions for the amplitude of displacements are also derived in explicit analytical form. Numerical results of the displacement amplitude in cantilever sandwich beam varying with damping coefficient are evaluated.

The flow field behavior in the vicinity of a perforated breakwater and the efficiency of the breakwater under regular waves were studied. To examine the efficiency of the structure thirteen types of regular wave conditions with wave periods T = 1, 1.2, 1.6, 2, 2.5 sec and wave heights Hi = 2, 4, 6, 8, 10 cm in an intermediate water depth of 50 cm were tested. The incoming, reflected and transmitted wave heights were measured using resistance type wave gauges positioned at the required locations. The efficiency of the structure was calculated considering the energy balance for the system. The efficiency of the structure for different wave conditions and with different parameters are shown and compared. Seven types of regular waves with wave periods T = 1, 1.6, 2, 2.5 sec and wave heights Hi = 4, 6, 8, 10 cm in an intermediate water depth of 50 cm were tested for the flow behavior study. In order to study the flow field variation with phase, ten phases were considered per one wave. The Particle Image Velocimetry (PIV) technique was employed to measure the two dimensional instantaneous velocity field distribution and MPIV (Matlab toolbox for PIV) and DaVis (a commercial software) were used to calculate the velocity vectors. By repeating the experiments and taking an average, the mean velocity field, mean vorticity field, mean turbulent intensity and mean turbulent kinetic energy field were calculated for each phase and for each wave condition. The phase average fields for each wave condition for each of the above mentioned parameters were calculated taking the average of ten phases. The phase averaged velocity, vorticity and turbulent kinetic energy fields are presented and compared. The energy dissipation based on both elevation data and the velocity data are presented and compared. It was found that for more than 75% of the tested wave conditions, the energy dissipation was above 69%. Thus the structure is very effective in energy dissipation. Further it was found that for all the tested wave conditions most of the turbulent kinetic energy form near the free surface and near the front wall, where as behind the back wall of the structure the turbulent kinetic energy was very small.

No description available.

Thesis (Ph. D.)--University of Adelaide, Dept. of Physics and Mathematical Physics, 1992. / Includes bibliographical references (leaves 231-241).

Thesis (Ph. D.)--University of Texas at Austin, 2002. / Vita. Includes bibliographical references. Available also from UMI Company.