The use of magnetorheological dampers for structure vibration mitigation has been largely considered due to the semi-active nature of their control. While the ability to deliver high-performance with a limited power s...
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ISBN:
(数字)9781510671997
ISBN:
(纸本)9781510671997;9781510671980
The use of magnetorheological dampers for structure vibration mitigation has been largely considered due to the semi-active nature of their control. While the ability to deliver high-performance with a limited power supply is attractive, it is imperative that the controls are properly developed under various excitation frequencies. However, because the desired control force may not directly be commanded to the magnetorheological damper, the employment of a secondary control to dictate the voltage applied to the damper is necessary. This proves further challenging due to the inability to invert the most accurate damper mathematical models. This research focuses on the assessment of multiple controller designs, including LQR and Skyhook, to determine their effectiveness under a wide range of excitation frequencies. The influence of limited sensing information is also analyzed through case studies.
Traditional vibration control dampers are sensitive to frequency modulation and very difficult to achieve long- period frequency modulation. The control effects of traditional dampers are not ideal in the face of comp...
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ISBN:
(数字)9781510671997
ISBN:
(纸本)9781510671997;9781510671980
Traditional vibration control dampers are sensitive to frequency modulation and very difficult to achieve long- period frequency modulation. The control effects of traditional dampers are not ideal in the face of complex and variable loads, and their robustness is low. Latching control is a phase optimization method applied in wave energy converters (WECs). Based on the latching control of WEC, this paper proposed the latched mass damper (LMD) and three different control strategies for the optimization of vibration control. The LMD can directly extend the periods to match well with the longperiod vibrations by introducing the latching forces. First, the theoretical model of LMD is established and analyzed. Then, the dynamic performances of LMDs with different strategies are compared. The results indicate that the proposed LMD and strategies for vibration control are feasible. The proposed latching control mechanism and strategies can provide an innovative solution for improving the efficiency of high-frequency detuned dampers, designing of long-period dampers with limited stroke spaces, and adaptive semi-active dampers in the future.
This research aims to establish a smart structure technology to measure and compensate for the minute displacements in large optical structures in orbit in real time. Structure-Optics coupling mechanism by Displacemen...
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ISBN:
(纸本)9781510660793;9781510660809
This research aims to establish a smart structure technology to measure and compensate for the minute displacements in large optical structures in orbit in real time. Structure-Optics coupling mechanism by Displacement correction strut for Active control of space telescope (SODA) will be designed, fabricated, and tested to demonstrate the technology through the ground test. SODA will consist of a 70 cm ceramic mirror and a smart strut with a displacement correction mechanism. This paper describes the results of functional verification testing of the smart strut and the test plan for SODA.
Nature through careful observation and tests of gliding avian species have resulted in new thoughts on how to design morphing uninhabited air vehicles (UAV) and what morphing motions might make for better performance....
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ISBN:
(纸本)9781510660793;9781510660809
Nature through careful observation and tests of gliding avian species have resulted in new thoughts on how to design morphing uninhabited air vehicles (UAV) and what morphing motions might make for better performance. An understanding of avian flight stability suggests a new approach to morphing aircraft design. Of interest is how to create these motions using smart materials to replicate avian abilities. Coupled with new learning algorithms, methods for designing smart autonomous morphing airfoils for use in small UAVs are presented. Hardware based reinforcement learning (RL) techniques are used to teach a smart morphing wing to respond to gusts, following the inspiration of gliding gulls who respond immediately and autonomously to unknown changes in flow to maintain stability and control in unpredictable environments. We strive to translate this knowledge to flight control of UAVs. Last, a way forward is suggested to create new class of structures: autonomous multifunctional structures. An outline of what is needed in terms of future research is presented.
The exploration of intelligent machines has recently spurred the development of physical neural networks, a class of intelligent metamaterials capable of learning, whether in silico or in situ, from observed data. In ...
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ISBN:
(数字)9781510671997
ISBN:
(纸本)9781510671997;9781510671980
The exploration of intelligent machines has recently spurred the development of physical neural networks, a class of intelligent metamaterials capable of learning, whether in silico or in situ, from observed data. In this letter, we introduce 'equilibrium learning', a novel physical learning rule designed for lattice-based mechanical neural networks (MNNs) to achieve target performance. This approach leverages the steady states of nodes for back-propagation, efficiently updating the learning degrees of freedom. One-dimensional MNNs, trained with equilibrium learning in silico, can exhibit the desired behaviors on demand function as intelligent mechanical machines. The approach is then employed for the precise morphing control of two-dimensional MNNs subjected to shear or uniaxial loads. Moreover, the MNN is trained to execute classical machine learning tasks such as regression, and preprogrammed bandgap control, establishing it as a versatile platform for physical learning. Our approach presents an efficient pathway for the design of lattice-based mechanical metamaterials for a wide range of static and dynamic target functionalities, positioning them as powerful engines for physical learning.
The demand for renewable energy has increased in recent years, including the market for micro wind turbines. However, low-cost products lack a proper control system and advanced features. This paper improves on an int...
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ISBN:
(数字)9781510671997
ISBN:
(纸本)9781510671997;9781510671980
The demand for renewable energy has increased in recent years, including the market for micro wind turbines. However, low-cost products lack a proper control system and advanced features. This paper improves on an integrated control system with real-time monitoring and braking capabilities. The prototype uses off-the-shelf components, reducing costs and not needing constant maintenance. The control electronics include a three-phase rectifier and a DC-DC converter to regulate the output voltage. To allow real-time control, a microcontroller measures the voltage, current, and turbine speed. An emergency stop button is also implemented to stop the turbine with an electronic brake. Primary system performance data is displayed in a user interface by a Raspberry Pi and stored for future analysis. Experimental results demonstrate the feasibility of the proposed control system for commercial micro wind turbines of 200 W and 400 W.
This paper introduces an innovative approach featuring a reinforced concrete beam that combines smart Fiber Reinforced Concrete beam integrated with Shape Memory Alloys (SMA-FRC) and Fiber Bragg Grating (FBG) sensors....
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ISBN:
(数字)9781510671997
ISBN:
(纸本)9781510671997;9781510671980
This paper introduces an innovative approach featuring a reinforced concrete beam that combines smart Fiber Reinforced Concrete beam integrated with Shape Memory Alloys (SMA-FRC) and Fiber Bragg Grating (FBG) sensors. Embedded FBGs serve as strain sensors for real-time structural monitoring while the SMA wires serve as integrated actuators to recover the excessive deflective and ensure the safety of the structure. The primary objective of the study is to assess the structural integrity and reliability of the SMA-FRC beam, particularly in terms of crack detection and crack width estimation. The remarkable properties of shape memory alloy wires, encompassing shape memory effect (SME) and superelasticity effect (SE), play a pivotal role in the system's performance and functionality. The SME and SE properties empower the beam to autonomously recover its deformation and effectively reduce crack width. Real-time measurements of strain, stress, and crack width are continuously collected by an integrated processing unit, providing valuable insights into the beam's reliability, and generating risk assessment reports. Upon detecting excessive strain and thus crack width by Embedded FBG sensors, the SMA wires will be activated to recover the excessive deformation. For low induced strain, the strain recovery will be performed using SE, while for high strain, the SME will be activated by induing electric energy. To assess crack development and propagation within the beams, a combination of ACI codes and analytical modelling techniques have been utilized. Additionally, regression methods are applied in conjunction with beam theories to derive continuous deflection profiles based on the optical signals of the FBG sensors. A proof-of-the-concept experimental test has been conducted to illustrate the performance and functionality of the smart SMA-FRC beam in crack monitoring and control. The research outcomes demonstrate that the incorporation of FBG sensors is an efficient means of
This research experimentally investigates the integration of mechano-intelligence into mechanical metastructures for self-adaptive wave control. We created a phononic metastructure prototype utilizing periodic buckled...
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ISBN:
(纸本)9781510660731;9781510660748
This research experimentally investigates the integration of mechano-intelligence into mechanical metastructures for self-adaptive wave control. We created a phononic metastructure prototype utilizing periodic buckled beam modules that has highly adjustable wave propagation characteristics via length reconfiguration using a linear displacement actuator. By utilizing the physical reservoir computing framework, we show that the proposed metastructure can recognize and self-adapt to different inputs by making decisions on appropriate actuations to reconfigure itself to achieve an intelligent wave blocking task. Overall, this research provided a promising approach for constructing and integrating functional mechano-intelligence in structures harnessing physical computing and learning, and created a new direction for the next generation of adaptive structures and material systems.
In this paper, a classification method of flutter test signals based on convolutional neural network (CNN) and Hilbert-Huang transform (HHT) is established, which can be effectively applied to flutter boundary predict...
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ISBN:
(数字)9781510672055
ISBN:
(纸本)9781510672055;9781510672048
In this paper, a classification method of flutter test signals based on convolutional neural network (CNN) and Hilbert-Huang transform (HHT) is established, which can be effectively applied to flutter boundary prediction. This method combines convolutional neural network and time-frequency analysis. Firstly, the flutter test signal is preprocessed by Hilbert-Huang transform and labeled according to the actual signal source. The label contains channel information and flutter information. All the signals and labels are composed of the dataset, the dataset is randomly scrambled and 80% of the number is taken as the training set, and the features are extracted, and the classification model is trained by convolutional neural network. The remaining 20% of the dataset is taken as the test set. The test set is used to test the classification model and verify the reliability and accuracy of the model. The accuracy of the final test set is above 90%, which indicates that the model trained by this method can effectively identify the channel information and the flutter information of the signal.
Wave propagation in periodic media is crucial for energy transmission, enabling control over energy direction and isolation. This involves breaking the inversion symmetry of a spring-mass chain by introducing mirrored...
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ISBN:
(数字)9781510671997
ISBN:
(纸本)9781510671997;9781510671980
Wave propagation in periodic media is crucial for energy transmission, enabling control over energy direction and isolation. This involves breaking the inversion symmetry of a spring-mass chain by introducing mirrored copies of periodic combinations, creating a unique, irreversible structure with distinct dispersion properties. The customizability and linearity of the interface lattice present the main challenge in controlling the interface mode. Our study focuses on designing a controllable on-demand interface mode using shape memory alloy-based smart material actuation mechanism. We included shape memory alloy-type springs along with the conventional springs in the analysis. SMA has the unique ability to change its phase in response to a temperature change due to the phase transition between martensite and austenite crystal structures. As a result, the modulus of elasticity also varies resulting in a change in stiffness. Through this system, the voltage-dependent stiffness can be tuned. This, in turn, enables the existence of an interface mode to be adjusted to the desired frequency and amplitude. The proposed system also allows us to obtain a range of split bandgaps that are dependent on controlling parameters. It is observed that the variation in the actuation voltage is to be controlled for the interface mode tuning and adjust stiffness accordingly. A generalized theoretical scheme is developed for several types of spring combinations at the interface and its effects are compared. Such system can significantly change the wave propagation in periodic media, leading to advancements in energy transmission systems with enhanced efficiency and versatility. Thus, the obtained interface mode within the bandgap can be tuned by the applied voltage enabling future application in wave focusing, wave guiding, and energy harvesting.
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