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You searched for +publisher:"Michigan State University" +contributor:("Diaz, Alejandro R"). Showing records 1 – 2 of 2 total matches.

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Michigan State University

1. Cai, Tingli. Vibration suppression in simple tension-aligned structures.

Degree: 2016, Michigan State University

Thesis Ph. D. Michigan State University. Mechanical Engineering 2016

Tension-aligned structures have been proposed for space-based antenna applications that require high degree of accuracy. This type of structures use compression members to impart tension on the antenna, thus helping to maintain the shape and facilitate disturbance rejection. These structures can be very large and therefore sensitive to low-frequency excitations. In this study, two control strategies are proposed for the purpose of vibration suppression. First, a semi-active control strategy for tension-aligned structures is proposed, based on the concept of stiffness variation by sequential application and removal of constraints. The process funnels vibration energy from low-frequency to high-frequency modes of the structure, where it is dissipated naturally due to internal damping. In this strategy, two methods of stiffness variation were investigated, including: 1) variable stiffness hinges in the panels and 2) variable stiffness elastic bars connecting the panels to the support structure. Two-dimensional and three-dimensional models were built to demonstrate the effectiveness of the control strategy. The second control strategy proposed is an active scheme which uses sensor feedback to do negative work on the system and to suppress vibration. In particular, it employs a sliding mechanism where the constraint force is measured in real time and this information is used as feedback to prescribe the motion of the slider in such a way that the vibration energy is reduced from the structure continuously and directly. The investigation of the sliding mechanism was performed numerically using the model of a nonlinear beam. Practical issues of this control scheme have been considered and measures such as adding a low-pass filter was taken to ease requirements on the control hardware. It has been shown in simulations that these two control strategies are effective mechanisms to remove energy from a vibrating system.To validate the control strategies, an experimental setup was built. A 3.66 meter long aluminum beam was placed on a rigid bench with a tension device applied at one end. A belt-driven actuator carried a slider, which moved axially along the surface of the beam. On the sliding interface, the slider imposed a constraint on the beam to maintain zero transverse displacement. Rotation at the sliding contact point, controlled by an electromagnetic brake, could be fixed instantaneously, or allowed to vary freely. The slider was equipped with strain gauges and an encoder to measure the constraint force from the beam. The sensor data was fed back and processed in real-time by a control algorithm implemented on a DSP board. Different control strategy combinations have been experimented on the system. Results showed that, with light material damping present in the structure, the two control strategies effectively redistributed the vibration energy into the high-frequency modes, where it was dissipated naturally and quickly.

Description based on…

Advisors/Committee Members: Mukherjee, Ranjan, Diaz, Alejandro R, Pence, Thomas, Wang, Chang Y.

Subjects/Keywords: Vibration; Damping (Mechanics); Structural control (Engineering); Mechanical engineering

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Cai, T. (2016). Vibration suppression in simple tension-aligned structures. (Thesis). Michigan State University. Retrieved from http://etd.lib.msu.edu/islandora/object/etd:3871

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Cai, Tingli. “Vibration suppression in simple tension-aligned structures.” 2016. Thesis, Michigan State University. Accessed January 23, 2020. http://etd.lib.msu.edu/islandora/object/etd:3871.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Cai, Tingli. “Vibration suppression in simple tension-aligned structures.” 2016. Web. 23 Jan 2020.

Vancouver:

Cai T. Vibration suppression in simple tension-aligned structures. [Internet] [Thesis]. Michigan State University; 2016. [cited 2020 Jan 23]. Available from: http://etd.lib.msu.edu/islandora/object/etd:3871.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Cai T. Vibration suppression in simple tension-aligned structures. [Thesis]. Michigan State University; 2016. Available from: http://etd.lib.msu.edu/islandora/object/etd:3871

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation


Michigan State University

2. Panigrahi, Smruti Ranjan. Dynamics of nonlinear snap – through chains with application to energy harvesting and wave propagation.

Degree: 2014, Michigan State University

Thesis Ph. D. Michigan State University. Mechanical Engineering 2014.

There is much current research interest in nonlinear structures, smart materials, and metamaterials, that incorporate bistable, or snap-through, structural elements. Various applications include energy harvesting, energy dissipation, vibration absorption, vibration isolation, targeted energy transfer, bandgap design and metamaterials. In this dissertation, we explore snap-through structures with nonlinearity and negative linear stiffness. We start with a study of a simple Duffing oscillator with snap-through orbits around the separatrix. Multi-degree-of-freedom snap-through structures are known to convert the low-frequency inputs into high-frequency oscillations, and are called twinkling oscillators. A generalized two-degree-of-freedom (2-DOF) snap-through oscillator is shown to have rich bifurcation structure. The steady-state bifurcation analysis uncovered two unique bifurcations "star" and "eclipse" bifurcations, named due to their structures. The 2-DOF twinkler exhibits transient chaos in the snap-through regime. A fractal basin boundary study provides insight into the regions in the parameter space where the total energy level is predictable in an unsymmetric twinkler. Due to its capacity to convert low frequency to high-frequency oscillations, the snap-through oscillators can be used to harvest energy from low-frequency vibration sources. This idea has led us to explore the energy harvesting capacity of twinkling oscillators. Using magnets and linear springs we built (in collaboration with researchers at Duke university) novel experimental twinkling oscillators (SDOF and 2-DOF) for energy harvesting. When the magnets exhibit high-frequency oscillations through the inducting coil, a current is generated in the coil. This experiment shows promising results both for the SDOF and the 2-DOF twinkling energy generators by validating the frequency up-conversion and generating power from the low-frequency input oscillations. The experimental twinkling oscillator converted a 0.1 Hz input oscillation into 2.5 Hz output oscillation, a 25 times frequency up-conversion. The second part of this dissertation focuses on the dispersive nature of the waves in one dimensional nonlinear chains with weak nonlinearity. For metamaterial design, it is important to study the wave dispersion properties in the material for channeling energy in a desired direction or to build frequency-selective materials. In nonlinear structures there are various design parameters that can be tuned to produce desirable properties. The motivation of the wave propagation analysis is to understand the quadratic and cubic nonlinearity effects on the wave propagation behavior in an uniform periodic chain. Here the dispersion properties are studied through a multiple-scales perturbation approach for weakly nonlinear periodic media. Wave speed, cut-off frequencies, and wave-wave interaction characteristics are presented. The results show significant effect of quadratic nonlinearities in…

Advisors/Committee Members: Feeny, Brian F, Diaz, Alejandro R, Shaw, Steven W, McGough, Robert J.

Subjects/Keywords: Mechanical engineering; Structural stability; Bistability; Energy harvesting; Energy; Applied mathematics

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Panigrahi, S. R. (2014). Dynamics of nonlinear snap – through chains with application to energy harvesting and wave propagation. (Thesis). Michigan State University. Retrieved from http://etd.lib.msu.edu/islandora/object/etd:3307

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Panigrahi, Smruti Ranjan. “Dynamics of nonlinear snap – through chains with application to energy harvesting and wave propagation.” 2014. Thesis, Michigan State University. Accessed January 23, 2020. http://etd.lib.msu.edu/islandora/object/etd:3307.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Panigrahi, Smruti Ranjan. “Dynamics of nonlinear snap – through chains with application to energy harvesting and wave propagation.” 2014. Web. 23 Jan 2020.

Vancouver:

Panigrahi SR. Dynamics of nonlinear snap – through chains with application to energy harvesting and wave propagation. [Internet] [Thesis]. Michigan State University; 2014. [cited 2020 Jan 23]. Available from: http://etd.lib.msu.edu/islandora/object/etd:3307.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Panigrahi SR. Dynamics of nonlinear snap – through chains with application to energy harvesting and wave propagation. [Thesis]. Michigan State University; 2014. Available from: http://etd.lib.msu.edu/islandora/object/etd:3307

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

.