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Full-Text Articles in Mechanical Engineering
3d Acoustic Pipe Locator Imaging Based On Finite Element Analysis, Yi Liu
3d Acoustic Pipe Locator Imaging Based On Finite Element Analysis, Yi Liu
Graduate College Dissertations and Theses
A more complex underground pipe system is growing with the expansion of cities. However, there is no comprehensive database of underground pipes. Thus, it is urgent to build database with materials, positions, diameters, and etc. To locate the pipes is the first step. There are many ways to find pipes such as metal detector, ground penetrating radar, and acoustic method. Metal detectors are becoming increasing ineffective with more and more nonmetal is using in pipes. Ground penetrating radar is a precise way to find pipes but it is only works well under low moisture environment. Additionally, ground penetrating radar is …
Dynamic Response Of A Hingeless Helicopter Rotor Blade At Hovering And Forward Flights, Pratik Sarker
Dynamic Response Of A Hingeless Helicopter Rotor Blade At Hovering And Forward Flights, Pratik Sarker
University of New Orleans Theses and Dissertations
The helicopter possesses the unrivaled capacity for vertical takeoff and landing which has made the helicopter suitable for numerous tasks such as carrying passengers and equipment, providing air medical services, firefighting, and other military and civil tasks. The nature of the aerodynamic environment surrounding the helicopter gives rise to a significant amount of vibration to its whole body. Among different sources of vibrations, the main rotor blade is the major contributor. The dynamic characteristics of the hingeless rotor consisting of elastic blades are of particular interest because of the strongly coupled equations of motion. The elastic rotor blades are subjected …
The Modeling Of Structural-Acoustic Interaction Using Coupled Fe/Be Method And Control Of Interior Acoustic Pressure Using Piezoelectric Actuators, Yucheng Shi
Mechanical & Aerospace Engineering Theses & Dissertations
A coupled finite element (FE) and boundary element (BE) approach is presented to model full coupled structural/acoustic/piezoelectric systems. The dual reciprocity boundary element method is used so that the natural frequencies and mode shapes of the coupled system can be obtained, and to extend this approach to time dependent problems. The boundary element method is applied to interior acoustic domains, and the results are very accurate when compared with limited exact solutions. Structural--acoustic problems are then analyzed with the coupled finite element/boundary element method, where the finite element method models the structural domain and the boundary element method models the …
Finite Element Model Of A Timoshenko Beam With Structural Damping, Louis Ablen Roussos
Finite Element Model Of A Timoshenko Beam With Structural Damping, Louis Ablen Roussos
Mechanical & Aerospace Engineering Theses & Dissertations
A numerical integration technique, a modified version of the Newmark method, is applied to transient motion problems of systems with mass, stiffness, and small nonlinear damping. The nonlinearity is cast as a pseudo-force to avoid repeated recalculation and decomposition of the effective stiffness matrix; thus, the solution technique is dubbed the "pseudo-force Newmark method." Comparisons with exact and perturbation solutions in single-degree-of-freedom problems and with a Gear-method numerical solution in a cantilevered Timoshenko beam finite element problem show the solution technique to be efficient, accurate, and, thus, feasible provided the nonlinear damping is small. As a preliminary step into the …