Browsing by Author "Li, Suyi"

Now showing 1 - 4 of 4
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    Energy Harvesting Hydraulically Interconnected Shock Absorber: Modeling, Simulation and Prototype Validation
    Deshmukh, Nishant Mahesh (Virginia Tech, 2023-07-09)
    The conventional car suspension system uses isolated shock absorbers that are only capable of dissipating energy in the form of heat. Each shock absorber in a hydraulic interconnected suspension is connected by hydraulic circuits, allowing the electrified hydraulic fluid to be used to counteract undesirable body motion and enhance dynamic performance as a whole. An established idea with good potential for managing body rolling and separating the warp mode from other dynamic modes is the hydraulic interconnected suspension. While certain active or semi-active suspension technologies enable the shock absorbers to compensate for the effects of the road disturbances using external power input, hydraulic linked suspension is still passive and lacks adaptivity. In order to adjust the suspension's damping properties to rapidly changing road conditions, active suspensions, like electromagnetic shock absorbers, utilize the magnetofluid's variable viscosity. In some circumstances, the energy requirement of an active suspension might amount to kilowatts, which lowers the vehicle's fuel efficiency. This research proposes a novel energy-harvesting hydraulically interconnected shock absorber (EH-HISA) system to find a balanced solution to dynamic performance and energy efficiency by incorporating energy harvesting ability to a passive hydraulically interconnected suspension. Improved energy efficiency and vehicle dynamics performance are provided by the features which combine energy harvesting with hydraulic interconnection. AMESim is used to build a single diagonal hydraulic circuit model, which is then validated in a bench test. The theoretical model's validity was established by the bench test results, and the model was then applied to estimate system performance. To verify the effectiveness of the entire system design, a full car model outfitted with EH-HISA is created. For model simulation, various dynamic input scenarios—including sinusoidal input and double lane change tests—are applied. The EH-HISA achieves average lateral acceleration improvements of 38% over traditional suspensions and 11% compared to a prior design (EHHIS proposed by Chen et al.) and average energy harvesting ability improvements of 133 % while maintaining acceptable anti-rolling dynamics in the double lane change test. The EH-HISA also improves the anti-rolling ability by 30 % as compared to traditional suspensions. The power generated is found to reach maximum of 210 W at 2 Hz and 20 mm sinusoidal input. Bench tests are performed on the EH-HISA prototype to validate the simulation results. Damping force and energy harvesting experimental data is measured and compared with the simulation results to validate the effectiveness of the system.
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    Hydroacoustic Parametric Study of Pile Driving-Induced Anthropogenic Sound
    Wojciechowski, Shannon (Virginia Tech, 2024-06-04)
    Anthropogenic sound in Florida's waters and coastal waterways is most commonly caused by overwater development, marine traffic, and military activity. Overwater construction has increased over the years as a result of aging infrastructure and rising expansions around the United States, including more than forty US Naval facilities containing tens of thousands of feet of pier. Construction methodology, such as pile driving, has risen in shallow waters to build structures such as bridges, piers, and wind farms, with significant consequences for marine life and the environment. More precisely, pile driving activities generate significant decibel levels in the surrounding marine environment. Measurements taken from hydrophones placed in the water near the construction site indicate that the high sound pressure levels produced may be harmful to marine life and the environment. As a result, standards have been established to help alleviate and decrease the possible harm that high decibel sound levels may produce. However, these additional steps increase the overall cost of the construction project. This thesis focuses on replicating the pile driving process using finite element modeling to hydroacoustic parametric study of pile driving-induced anthropogenic sound in neighboring Florida seas, as well as the possible environmental impact of the state's numerous naval base piers. The modeling predictions can then be used to identify the distance from the pile at which marine life and the environment are no longer adversely affected. In addition, computer modeling can reduce construction costs when compared to on-site sensors and monitoring.
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    Multi-functional Holographic Acoustic Lenses for Modulating Low- to High-Intensity Focused Ultrasound
    Sallam, Ahmed (Virginia Tech, 2024-03-27)
    Focused ultrasound (FUS) is an emerging technology, and it plays an essential role in clinical and contactless acoustic energy transfer applications. These applications have critical criteria for the acoustic pressure level, the creation of complex pressure patterns, spatial management of the complicated acoustic field, and the degree of nonlinear waveform distortion at the focal areas, which have not been met to date. This dissertation focuses on introducing experimentally validated novel numerical approaches, optimization algorithms, and experimental techniques to fill existing knowledge gaps and enhance the functionality of holographic acoustic lenses (HALs) with an emphasis on applications related to biomedical-focused ultrasound and ultrasonic energy transfer. This dissertation also aims to investigate the dynamics of nonlinear acoustic beam shaping in engineered HALs. First, We will introduce 3D-printed metallic acoustic holographic mirrors for precise spatial manipulation of reflected ultrasonic waves. Optimization algorithms and experimental validations are presented for applications like contactless acoustic energy transfer. Furthermore, a portion of the present work focuses on designing holographic lenses in strongly heterogeneous media for ultrasound focusing and skull aberration compensation in transcranial-focused ultrasound. To this end, we collaborated with the Biomedical Engineering and Mechanics Department as well as Fralin Biomedical Research Institute to implement acoustic lenses in transcranial neuromodulation, targeting to improve the quality of life for patients with brain disease by minimizing the treatment time and optimizing the ultrasonic energy into the region of interest. We will also delve into the nonlinear regime for High-Intensity Focused Ultrasound (HIFU) applications, this study is structured under three objectives: (1) establishing nonlinear acoustic-elastodynamics models to represent the dynamics of holographic lenses under low- to high-intensity acoustic fields; (2) validating and leveraging the resulting models for high-fidelity lens designs used in generating specified nonlinear ultrasonic fields of complex spatial distribution; (3) exploiting new physical phenomena in acoustic holography. The performed research in this dissertation yields experimentally proven mathematical frameworks for extending the functionality of holographic lenses, especially in transcranial-focused ultrasound and nonlinear wavefront shaping, advancing knowledge in the burgeoning field of the inverse issue of nonlinear acoustics, which has remained underdeveloped for many years.
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    Phononic Bandgap Programming in Kirigami By Unique Mechanical Input Sequencing
    Khosravi, Hesameddin; Li, Suyi (Wiley, 2023-04)
    This study investigates the programming of elastic wave propagation bandgaps in periodic and multi-stable metamaterials by intentionally and uniquely sequencing its constitutive mechanical bits. To this end, stretched kirigami is used as a simple and versatile testing platform. Each mechanical bit in the stretched kirigami can switch between two stable equilibria with different external shapes (aka. "(0)" and "(1)" states). Therefore, by designing the sequence of (0) and (1) bits, one can fundamentally change the underlying periodicity and thus program the phononic bandgap frequencies. This study develops an algorithm to identify the unique periodicities generated by assembling "n-bit strings" consisting of n mechanical bits. Based on a simplified geometry of these n-bit strings, this study also formulates a theory to uncover the rich mapping between input sequencing and output bandgaps. The theoretical prediction and experiment results confirm that the (0) and (1) bit sequencing is effective for programming the phonic bandgap frequencies. Moreover, one can additionally fine-tune the bandgaps by adjusting the global stretch. Overall, the results of this study elucidate new strategies for programming the dynamic responses of architected material systems.