查看更多>>摘要：Regenerative chatter is a prevalent issue in machining, stemming from the instability of self- excited vibrations within the tool or workpiece. Operational Modal Analysis (OMA) of the tool or workpiece vibrations during turning operations is an effective method to predict and mitigate chatter. However, it requires substantial input from an expert user, undermining its application in process monitoring. This paper presents an Automated Operational Modal Analysis (AOMA) approach to elim- inate user intervention from the online chatter prediction process. The proposed approach combines clustering algorithms with knowledge about the system's underlying physics to eliminate spurious poles as well as those representing the undamped harmonic oscillations. As a result, the dominant pole of self-excited dynamics is identified automatically, quantifying the stability of process vibrations. The accuracy and effectiveness of the proposed method are validated through experiments and numerical simulations.
查看更多>>摘要：The Duffing adaptive oscillator is constructed as a mechanical system. Using the frequency- amplitude relationship, the Duffing adaptive oscillator is compared with the non-adaptive Duffing oscillator. It was found that the adaptive state can learn the resonance, whether the frequency state is initialized above or below the forcing frequency. Of particular interest, this system is capable of both physical reservoir computing and analog signal processing. Coupling these with the Duffing adaptive oscillator's enhanced stochastic resonance, the Duffing adaptive oscillator is well-suited for industrial AI applications that require signal processing and machine learning in the presence of noise. A mechanical prototype of the Duffing adaptive oscillator is presented, and its potential as a physical reservoir computer is demonstrated using several tasks.
Rik VaerenbergWade A. SmithRobert B. RandallKonstantinos Gryllias...
112716.1-112716.13页
查看更多>>摘要：Variable frequency drives used to control the speed of electrical motors in mechanical driv- etrains can cause impulsive electromagnetic interference (EMI). Due to the impulsiveness of the EMI, classical blind spectral kurtosis based approaches in vibration monitoring are not able to extract bearing faults. Therefore, this work proposes the use of FRESH filters to extract the impulsive EMI content and remove it from the original signal. The proposed EMI removal methodology approach allows for blind spectral kurtosis based approaches to extract bearing faults even with severe impulsive EMI. In addition to this a high central frequency resolution Kurtogram is proposed, which allows for a higher resolution of the central frequency in the Kurtogram. Finally, the use of FRESH filters for bearing fault extraction is considered, demonstrating that this approach can also effectively extract bearing faults.
查看更多>>摘要：Effective remaining useful life prediction in the absence of target domain labels relies heavily on domain adaptation to transfer knowledge from a labeled source domain to an unlabeled target domain. However, privacy concerns in industries such as aerospace and manufacturing often render source data inaccessible due to the confidentiality of degradation information. Furthermore, existing source-free DA methods face significant challenges when applied to target domains with incomplete degradation trajectories, which can severely hinder their performance in RUL prediction tasks. To address these challenges, we propose a novel Calibrated Uncertainty for RUL Adaptation method, CURA, designed to enable source-free RUL prediction. Our approach begins with pretraining a model on the source domain using evidential learning to estimate both RUL values and associated uncertainties. The model is then adapted to the target domain by calibrating its uncertainty, ensuring consistency in uncertainty levels between the source and target domains while dynamically focusing on challenging samples. To determine when to stop training without target labels, we introduce a termination criterion based on the number of remaining challenging samples. Extensive experiments on the C-MAPSS and N-CMAPSS datasets demonstrate that CURA achieves superior performance, surpassing state- of-the-art source-free methods by an average of 69% on C-MAPSS and 53% on N-CMAPSS. Remarkably, CURA also outperforms state-of-the-art non-source-free methods by an average of 23% on C-MAPSS and 3% on N-CMAPSS, highlighting its exceptional effectiveness for source-free RUL adaptation.
Patrick HippoldGleb KleymanLukas WoiwodeTong Wei...
112732.1-112732.18页
查看更多>>摘要：Sinusoidal excitation is particularly popular for testing structures in the nonlinear regime. Due to the nonlinear behavior and the inevitable feedback of the structure on the exciter, higher harmonics in the applied excitation are generated. This is undesired, because the acquired response may deviate substantially from that of the structure under purely sinusoidal excitation, in particular if one of the higher harmonics engages into resonance. We present a new approach to suppress those higher excitation harmonics and thus the unwanted exciter-structure interaction: Higher harmonics are added to the voltage input to the shaker whose Fourier coefficients are adjusted via feedback control until the excitation is purely sinusoidal. The stability of this method is analyzed for a simplified model; the resulting closed-form expressions are useful, among others, to select an appropriate exciter configuration, including the drive point. A practical, model-free procedure for the control design is suggested. The proposed method is validated in virtual and physical experiments of internally resonant structures, in the two common configurations of force excitation via a stinger and base excitation. Excellent performance is achieved when simply using the same control gains for all harmonics, throughout the tested range of amplitudes and frequencies, even in the strongly nonlinear regime. Compared to the iterative state of the art, it is found that the proposed method is simpler to implement, enables faster testing and it is easy to achieve a lower harmonic distortion.
Iman DabbaghchianThomas J. MatarazzoSoheil Sadeghi EshkevariLiam Cronin...
112735.1-112735.17页
查看更多>>摘要：Recently, crowdsourced smartphone-vehicle trip (SVT) data has enabled cost-effective estima- tion of bridge modal frequencies and absolute mode shapes. SVT data includes acceleration and GPS measurements collected from smartphones within vehicles as they cross the bridge. The SVT data is inherently contaminated mostly with sensor noise, vehicle dynamics, and road profile uncertainties. These factors cause variability in the amount of embedded bridge dynamic information, thereby affecting the overall data quality. This study presents a novel method and metric to quantify the SVT data's quality based on each trip's impact on the identified aggregated mode shape. Then, a data-driven model is used to detect the quality parameter automatically using the convolutional neural network. The model is trained and tested on over 900 asynchronous SVT data collected from smartphones over the Cadore viaduct bridge in Italy. The results demonstrated that this method could improve the quality of an identified mode shape, increasing the modal assurance criterion of 0.8 in blind aggregation to 0.97 with model sorting and eliminating low-quality trips. Ensuring the quality control of crowdsourced data is crucial due to multiple noise sources, and discarding erroneous datasets can significantly improve dynamic characterization identification of the bridge.
查看更多>>摘要：Periodic excitations caused by wheel out-of-roundness (OOR) significantly affect vehicles, track structures, and passenger ride quality. Although numerous studies have investigated the forma- tion mechanisms and mitigation measures for wheel OOR, existing studies remain insufficient to fully prevent its occurrence. Consequently, monitoring wheel OOR has become increasingly crucial. To improve the efficiency and accuracy of OOR detection, this study proposes a model-based method that considers rail flexibility and multi-wheel interaction. The model is validated using field test data, and its performance is further verified through simulation cases and practical application. The results demonstrate the method's ability to reconstruct wheel roughness, effectively detecting both its magnitude and phase. Compared with traditional methods, incorporation of rail flexibility into the transfer function significantly enhances the accuracy of wheel roughness estimation using axle box acceleration (ABA), particularly during wheel-rail coupled system resonance. For wheel OOR dominated by frequencies below 100 Hz, both single- and multi-wheel coupling models provide reliable estimates. However, at higher dominant frequencies, multi-wheel coupling effects must be considered to address localized rail bending. Moreover, utilizing ABA from multiple wheels effectively eliminates multi-wheel interaction effects, significantly improving the accuracy of wheel OOR detection.
查看更多>>摘要：The solution of derivate moments in reduced dimension probability evolution equation (RDPEE) is still a difficult task in current research, especially for complex systems. This paper introduces the cell renormalized method, which dissects state and probabilistic space, is applied to numerically calculate the derivate moments of cell-centered coordinates. Then, an efficient nonlinear regression method based on Bayesian inference named Gaussian process regression is used to obtained the continuous curve of derivate moments in state space. Eventually, by solving the RDPEE via path integral solution, the final probability distribution can be recovered without difficulty. To illustrate it, several numerical examples, which include uni-modal and multi-modal distributions, simple and complex dynamical systems, Markov and non-Markov cases, are all considered to validate the high accuracy and efficiency of proposed method.
查看更多>>摘要：The cross-spectral density (Cross-SD; CSD) can be used to explore the relationship between random input forces and responses in the frequency domain. Furthermore, it can identify antiresonance frequencies more accurately than direct-SD. The ring structure is excellent in geometrical simplicity and structural stability, and thus can be applied into potential applications in various fields such as nanosensors and actuators. In this study, the frequency response function, autocorrelation function, and SD are defined for a unit force harmonic input based on Gaussian white noise applied to the ring structure. Then, the cross- and direct-SDs are compared to provide a new perspective on vibration analysis. Additionally, the variation of SD is analyzed based on the location of the responses, the standard deviation (StDev) of the maximum response, and the bandwidth. As a result, the significance of investigating eigenfrequencies and antiresonances can be illustrated through a simple computational model. Moreover, the proposed approach also shows significant potential for practical applications, such as predicting fatigue life and vibration control in structural engineering. In this study, a novel method is presented to advance vibration engineering by extending the SD model of beams to ring structures.
查看更多>>摘要：The transverse vibration of propulsion shafting is challenging to control due to many vibration sources and complex transmission paths. This paper aims at the main transmission path of transverse vibration: water-lubricated stern bearing (WLSB), and proposes a semi-active vibration control scheme of WLSB with magnetorheological squeezing film damper (MSFD) structure. The comprehensive dynamic characteristic model and finite element model are established to study the load-carrying performance, magnetic field intensity distribution, and dynamic characteristics of the MSFD-WLSB system. Further, the MSFD-WLSB with a semi-active vibration control system is designed and manufactured to conduct performance experiments under variable rotational speed and excitation on the test rig. The system's controller is developed using intelligent algorithms based on the test data, and the vibration attenuation capability of the semi-active vibration control system is verified under different operating conditions. The experiment results indicate that the proposed vibration control scheme can effectively reduce the vibration of different supporting components of the rotational shaft, especially for operation conditions of low speed and high external excitation frequency. The research results provide a new method for the transverse vibration attenuation of ship propulsion shafting.
NETL
NSTL
Elsevier