Search for: All records

Abstract This study focuses on laying the groundwork for the effective vibration suppression of power lines using mobile damping robots (MDR). Earlier research shows that effective vibration suppression is achieved by positioning the MDR at the anti-nodes of the power line. This study focuses on accurately estimating the dynamic state of the power line using a data-driven approach, hence identifying the position of the antinode. The entire dynamics of the vibration of the system is estimated from the displacement data of the power line using Dynamic Mode Decomposition (DMD) and the resulting system is stabilized with Tikhonov Regularization. The stabilized system is then used in conjunction with a Kalman Filter to accurately estimate the dynamic state of the power line using minimal displacement. All displacement data used in this study is acquired from a Galerkin model of the power line. This study shows that this method is a viable alternative to existing numerical methods which are often computationally expensive and time-consuming. 

Abstract Aeolian vibration is a significant factor contributing to the fatigue failure of power transmission lines. The mitigation of such vibrations in power lines has traditionally been achieved using Stockbridge dampers along the line spans, which are modeled as fixed vibration absorbers. They largely depend on their resonant frequencies and placement on the cable. Therefore, given the stochastic nature of the wind, recent studies have explored the concept of dynamic/moving absorbers. Although the effectiveness of the moving absorber has been demonstrated in the literature to be superior to that of the fixed absorber, analyses have primarily been limited to linear cases and have not accounted for nonlinearity introduced by the moving absorber or the wind inflow on the powerline. Aiming to fill this gap, this work combines the nonlinearities from the fluctuating lift force modeled as a van der Pol oscillator, with a nonlinear moving absorber into a single model to investigate the effect of a nonlinear mobile damper relative to its linear counterpart. We observe that the system with a nonlinear moving absorber exhibits smaller amplitude oscillations when compared to its linear counterpart. This finding underscores the superior mitigation characteristics of nonlinear vibration absorbers and suggests the potential for designing an optimal nonlinear moving vibration absorber. 

Abstract Several investigators have taken advantage of electromagnetic shunt-tuned mass dampers to achieve concurrent vibration mitigation and energy harvesting. For nonlinear structures such as the Duffing oscillator, it has been shown that the novel nonlinear electromagnetic resonant shunt-tuned mass damper inerter (NERS-TMDI) can mitigate vibration and extract energy for a wider range of frequencies and forcing amplitudes when compared to competing technologies. However, nonlinear systems such as the NERS-TMDI are known to exhibit complex stability behavior, which can strongly influence their performance in simultaneous vibration control and energy harvesting. To address this problem, this paper conducts a global stability analysis of the novel NERS-TMDI using three approaches: the multi-parametric recursive continuationWe emphasize that these assume method, Floquet theory, and Lyapunov exponents. A comprehensive parametric analysis is also performed to evaluate the impact of key design parameters on the global stability of the system. The outcome indicates the existence of complex nonlinear behavior, such as detached resonance curves, and the transition of periodic stable solutions to chaotic solutions. Additionally, a parametric study demonstrates that the nonlinear stiffness has a minimal impact on the linear stability of the system but can significantly impact the nonlinear stability performance, while the transducer coefficient has an impact on the linear and nonlinear stability NERS-TMDI. Finally, the global sensitivity analysis is performed relative to system parameters to quantify the impact of uncertainty in system parameters on the dynamics. Overall, our findings show that simultaneous vibration control and energy harvesting come with a considerable instability trade-off that limits the range of operation of the NERS-TMDI. 

Abstract The impact of the vibration absorber on the synchronization region during vortex-induced vibration of turbine blades is investigated. This work is based on a 3DOF model, including a coupled plunge-pitch airfoil motion and a van der Pol oscillator to the fluid-structure interaction caused by the vortex shedding of the incoming flow. The aeroelastic system is increased by a degree of freedom, namely, the vibration absorber. Linear and nonlinear vibration absorbers are used in this investigation to analyze the effectiveness of the vibration absorber. To demonstrate the effect of the resonator on the lock-in, the coupled natural frequencies, numerical frequency responses, and time histories are plotted. The study reveals the promising capability of the absorber to reduce the lock-in region and mitigate the VIV amplitudes within these regions. For the current application, however, the nonlinear absorber response was indifferent compared to its linear counterpart for the given values of coupling coefficients. This observation indicates that a linear absorber efficiently shrinks the lock-in regions and mitigates the VIV in turbomachinery. 

Abstract Fixed passive vibration absorbers (FPVAs) are widely used on power lines and other continuous systems, but they are inherently limited since changes in wind conditions affect absorber performance due to changing mode shapes. A mobile damping robot (MDR) can overcome these limitations by actively transporting a passive absorber to conductor antinodes where the absorbers can most effectively remove energy from the system. While many analyses have been performed for fixed masses on power line conductors, they have not been in the context of interactions between the conductor and a mobile damping robot (MDR). There is a need to explore the potential impact of the MDR on the power line and the resulting implications for the MDR’s development as current methods of vibration control do not adequately address fatigue failure caused by wind-induced vibrations (WIV). In this paper, we define a mathematical model of the system and perform numerical analysis in MATLAB® using equations of motion obtained via Hamilton’s Principle. We investigate the adequacy of an experimental test bench for testing. Then we experimentally validate the ability of a mobile robot to transport a mass along a conductor to antinode locations. Experimental results indicate that the robot is able to navigate to the locations of highest amplitude on the cable. The insights gained from this work lay a foundation to guide future experiments that will better define the operating conditions of the MDR and lead to the creation of an appropriate control framework. 

While analyses have been performed for fixed masses on power line conductors, they have not been in the context of interactions between the conductor and a mobile damping robot (MDR). There is a need to explore the potential impact of the MDR on the power line and the resulting implications for the MDR’s development as current methods of vibration control do not adequately address fatigue failure caused by wind-induced vibrations (WIV). Fixed passive vibration absorbers (FPVAs) are widely used on power lines, but they are inherently limited by their fixed nature since changes in wind conditions affect absorber performance as conductor mode shapes change. An MDR can overcome these limitations by actively transporting a passive absorber to conductor antinodes where the absorbers can most effectively remove energy from the system. In this paper, we experimentally investigate the effects of an untuned suspended mass on the conductor as an analog for the MDR, and we perform numerical analysis in MATLAB using equations of motion obtained via Hamilton’s Principle. The insights gained from this work lay a foundation to guide future experiments that will better define the operating conditions of the MDR and lead to the creation of an appropriate control framework.