Intelligent spindles are core components of the next-generation of intelligent/smart machine tools in the Industry 4.0 Era. The purpose of this paper is to clarify the concept of intelligent spindles and provide an in-depth review of the state-of-the-art of related technologies. A new integrated concept for intelligent spindles is proposed, followed by descriptions of required characteristics, key enabling technologies and expected intelligent functions. Relevant research that may be beneficial to the development of intelligent spindles is reviewed from six thrust areas, which include monitoring and control of tool condition, chatter, spindle collision, temperature/thermal error, spindle balance, and spindle health. Finally, current limitations and challenges are discussed, and future trends of intelligent spindles are prospected from various perspectives.

The concept and progress of intelligent spindles: A review

Matching synchrosqueezing transform: A useful tool for characterizing signals with fast varying instantaneous frequency and application to machine fault diagnosis

Parameterised time-frequency analysis methods and their engineering applications: A review of recent advances

Underwater Dynamic Response at Limited Points Expanded to Full-Field Strain Response

Detection of rub-impact fault for rotor-stator systems: A novel method based on adaptive chirp mode decomposition

With the development of active noise and vibration control technology, there are increasing demands for active noise and vibration reshaping (ANVR) other than cancellation in the fields of active s...

Multiple-harmonic amplitude and phase control method for active noise and vibration reshaping:

Since increasing demands for high efficiency of high speed rotating machines in recent years, the clearance between rotor and stator becomes smaller and smaller. Consequently, rub-impact fault is more likely to occur. It has become one of the most common and serious malfunctions for rotor system in practical engineering. Because the rub-impact severely induces the rotor dynamic instability, it will finally result in catastrophic failures and great economic loss if undetected in time. The occurrence of the rub-impact leads to a contact force between rotating shaft and stator which can be regarded as an additional support on the rotor system. The contact force will further result in the stiffening effect. As a result, some fast time-varying phenomena of vibration responses including the fast time-varying transient stiffness and the fast oscillated instantaneous frequency (IF) may appear. These phenomena may offer abundant characteristics to diagnose the rub-impact fault of rotor system. In this paper, an effective method based on the fast oscillated characteristics of IF for vibration responses is proposed to detect rub-impact fault of rotor bearing system. First of all, the fast time-varying transient stiffness of rub-impact rotor system is qualitatively formulated based on the Jeffcott rotor model and the fast oscillated characteristics of IF is presented and theoretically analyzed. Second, a time-frequency technique called nonlinear squeezing time-frequency transform (NSTFT) is introduced to extract the fast oscillated IF resulting from the rub-impact fault of rotor systems. Numerical simulations are respectively conducted on the Jeffcott rotor system with linear stiffness and oil film bearings. And then the oscillated characteristics of the IF are analyzed. The analysis results suggest that the IF of the vibration responses remains constant at the rotating frequency if there is no rub-impact fault. However, if rub-impact fault occurs, the IF of the vibration responses will oscillate periodically around the basic harmonic frequency. Furthermore, the oscillation law of the IF of vibration responses for rub-impact rotor systems is also numerically investigated. It is found that the oscillation frequency is the 1/k (k = 1, 2, 3, ...) of the rotating frequency if the rotor system operates at periodic-k motion. Finally, rub-impact fault experiments are performed under different operating regimes. The experimental results are consistent with the numerical results, thus demonstrating the validity and the practicability of the proposed method.Copyright © 2016 by ASME

Rub-Impact Detection of Rotor Systems Using Time-Frequency Techniques

\n This study aims at the comparative analysis and improvement of different analytical crack models for rotating blade. Part II of this study focuses on the comparative analysis of dynamic characteristics based on modified models mentioned in Part I. A nonlinear damage indicator (NDI) and an equivalent energy indicator (EEI) are introduced to characterize the nonlinear effect of crack from different perspectives. EEI offers a physical mechanism explanation of crack closing behavior, which is invisible. Meanwhile, NDI offers an observable indicator to quantify the nonlinearity of crack. It is demonstrated through the numerical study that the variation of NDI and EEI varies the same with each other, which cross-verified the validity of NDI and EEI for quantifying the nonlinear effect of crack. Comparative investigations are performed to analyze the effects of load amplitude, crack depth, and crack location on the nonlinear dynamics of cracked blade, and both NDI and EEI are utilized to quantify the nonlinear effects of crack. The comparative results suggest that NDI of the second-order super-harmonic component increases with the increasing crack depth and excitation load amplitude and decreases with the increasing crack locations, while the variation of EEI follows the variation of NDI. This phenomenon indicates that the crack, which is deeper and closer to blade root under a larger load will be more dangerous. This study’s comparative results may provide some guidance for choosing the analytical crack models when analyzing the nonlinear dynamics of rotating cracked blade and blade health monitoring.

Dynamic Characteristic Analysis of Rotating Blade With Transverse Crack—Part II: A Comparison Study of Different Crack Models

Rotating blade is one of the most important components for turbomachinery. Blade crack is one of the most common and dangerous failure modes for rotating blade. Therefore, the fault mechanism and f...

https://journals.sagepub.com/doi/pdf/10.1177/14613484211012602

An improved analytical dynamic model for rotating blade crack: With application to crack detection indicator analysis:

Continuum robot, unlike conventional rigid-link robots, has numerous numbers of degrees of freedom, enabling it to be applied for confined space works, such as minimally invasive surgery, safe robot/objective interactions, and in-situ aero-engine detection. This study presented a cable-driven continuum robot with twin-pivot structure, which poses smaller diameter-length-ratio and torsion resistance ability compared with conventional single-pivot structure, as well as the kinematics and shape estimation. The kinematics model of the twin-pivot continuum robot is established based on the assumption of piecewise constant curvature, with which the mapping between driving space and operation space are presented. Finally, a prototype of continuum robot system with single section is constructed to verify the validation of the kinematics model and study the shape estimation. Based on the constructed prototype, the shape estimation of the continuum robot with different payloads is performed. The comparative results suggest that relative error is less than 5% for total length of the single section without payload, verifying the validity of the kinematics model. The comparison between the results with different payloads indicate that the increasing payload will increase the relative error.

Laihao Yang

Papers

Multiple-harmonic amplitude and phase control method for active noise and vibration reshaping:

Rub-Impact Detection of Rotor Systems Using Time-Frequency Techniques

Dynamic Characteristic Analysis of Rotating Blade With Transverse Crack—Part II: A Comparison Study of Different Crack Models

An improved analytical dynamic model for rotating blade crack: With application to crack detection indicator analysis:

A Continuum Robot with Twin-Pivot Structure: The Kinematics and Shape Estimation