Baijie Qiao

Xi'an Jiaotong University | XJTU · School of Mechanical Engineering

Dynamic strain measurements of rotating blades have attracted significant attention in the turbomachinery design, testing, and service stages. Measuring the blade full-field strain using traditional strain gauges (SGs) is difficult. Too many SGs may add damping to the measured blades, thereby lowering the peak strain that should have been experienc...

The internal gear is part of the planetary and epicyclic gear pairs in the transmission system of the helicopter. Gear tooth wear is one of the most usual gear failures. This paper establishes an analytical model to evaluate the influence of tooth wear on the mesh relationship. A new mesh relationship can be derived for internal spur gears with too...

Aeroelastic instabilities will occur to the aero-engine fans inevitably during transient operations, causing excessive blade vibration and threatening the structural integrity. However, the complicated fluid-solid coupling interactions in aero-engine are difficult to be described precisely using current numerical or analytical models. Instead, expe...

It is challenging to realize impact localization and time history reconstruction simultaneously in practice. Ill-posed and under-determined problems are usually encountered due to the confined and harsh measuring conditions. ℓ1 regularization has been a favoured way to help gain sparse and accurate solutions, while ℓ1 -minimization is a biased esti...

The peak stress for the high-speed rotating blade is time-varying and space-varying under multi-mode vibration, which affects the measurement accuracy of dynamic strain. The full-field dynamic strain reconstruction method for high-speed rotating blades under multi-mode vibration is proposed based on limited measured strain data to ameliorate the st...

Dynamic strain of rotating blades is critical in turbomachinery health monitoring and residual life evaluation. Though the blade tip timing (BTT) technique is promising to replace traditional strain gages, the lack of effective strain transformation through BTT hinders the implementation. In this paper, a noncontact dynamic strain reconstruction me...

Azimuthal mode analysis is regarded as an effective tool for aero-engine flow field investigation, where numerous microphones are evenly mounted as a ring to provide sufficient spatial resolution for azimuthal pressure acquisition. The current compressive sampling method enables azimuthal modes to be obtained from much fewer microphones, with domin...

Gear wear is one of the most common gear failures, which changes the mesh relationship of normal gear. A new mesh relationship caused by gear wear affects meshing excitations, such as mesh stiffness and transmission error, and further increases vibration and noise level. This paper aims to establish the model of mesh relationship and reveal the vib...

Dynamic strain measurement is critical in blade vibration monitoring for evaluating the residual life and health condition of rotating blades. Blade tip time (BTT) is recognized as a promising technique to replace traditional strain gauge measurement. This paper presents a method for dynamic strain reconstruction as well as vibration parameter iden...

Although extensively studied, impact force identification is still a challenging task. When the location of the impact force is unknown, an under-determined problem is usually required to be tackled. In this paper, a novel impact force identification method based on the nonconvex overlapping group sparsity(NOGS) is proposed, allowing to localize th...

Investigations on the acoustic modes generated by the ducted fan can provide indispensable guidance for active control of the aero-engine noise. To achieve this, the circumferential pressure of the duct needs to be measured. However, the direct way, mounting a full sensor array (FSA) on the duct wall, requires numerous microphones and leads to a hi...

Rotor blade health monitoring based on the non-contact blade tip timing (BTT) technique has already been proved to be an alternative method to the classical contact strain measurement method. However, the signal sampled by the BTT system is usually undersampled due to the limited BTT sensors. Sparse regularization in the framework of ℓ1-norm has be...

The effects of temperature and twin grain boundary position on the crack propagation mechanism of pure α-Ti were studied by molecular dynamics simulation. Under room temperature, the twin grain boundary in the intergranular crack model can guide the crack propagation path and the formation of voids intensifies the crack propagation. With the increa...

A dynamic strain reconstruction method of rotating blades based on response transmissibility was proposed.Based on the characteristics of system strain frequency response, an analytical expression of the strain-strain response transmissibility with respect to the modal shape was obtained within the frequency domain, and the mapping between the meas...

Blade fatigue fracture is a serious aero-engine fault that may lead to an aircraft crash. It is essential for ensuring the safety of the aero-engine operation to monitor the blade crack propagation. Generally, the crack propagation of rotor blades can be detected by the natural frequency shift. The time-frequency analysis method with high time-freq...

Acoustic mode detection is attached great significance for providing guidance to noise reduction design of commercial aero-engine with high-bypass ratio. Compressive sampling method has been creatively employed in this field due to its notable performance on reducing the number of microphones in acoustic mode measurements. However, the classical ℓ1...

With the lubrication conditions deteriorating, sliding friction appears and affects the dynamic performance of planetary gear sets significantly. Furthermore, sliding friction can accelerate tooth surface fatigue and consequently cause many kinds of tooth failures. Spalling defect is a typical tooth failure of planetary gear sets. The influence of...

Nitrogen is one of the most significant foreign interstitial elements into Fe. The initial stage nitridation could dramatically influence mechanical property of steel especially for micro to nanoscale applications but has not yet been fully understood. By means of reactive force field molecular dynamics (ReaxFF MD) simulation, initial stage of nitr...

Gear wear is a typical and common early failure, which could lead to geometric deviation of tooth surface, further affecting vibration signal and transmission error. This paper is devoted to analyzing fault mechanism and dynamic characteristics of gear wear, which provides the basis for vibration-based fault diagnosis and monitoring of gear wear. F...

Blade tip timing (BTT) as a noncontact measurement technique is developed to monitor the health condition of aero-engine rotor blades. The circumferential placement of BTT sensors plays an important part in identifying blade vibration parameters. If the placement is suboptimal, the reconstructed displacement signal can be sensitive to the measureme...

To provide a simple numerical formulation based on fixed grids, a wavelet element method for fluid–solid modelling is introduced in this work. Compared with the classical wavelet finite element method, the presented method can potentially handle more complex shapes. Considering the differences between the solid and fluid regions, a damping-like int...

As a typical inverse problem, impact force identification tends to be a challenge owing to its ill-posedness. Recently, the sparse characteristic of the impact force in time domain are taken into consideration to convert the ill-posed problem into a sparse recovery task. The classic way to obtain sparse approximate solutions of impact force is to u...

It is the prerequisite for mechanical diagnosis to clarify the mapping relations between vibrations and damage conditions based on the dynamic model analyses and the systematic experiments. However, there is a certain deviation from the actual measurements in the existing planetary dynamic modeling methods which utilizes linear models or just consi...

Many convex regularization methods, such as the classical Tikhonov regularization based on l2-norm penalty and the standard sparse regularization method based on l1-norm penalty, have been widely investigated for impact force identification. However, in many practical applications, these regularization methods commonly underestimate the true soluti...

Acting as an important internal excitation, sliding friction can cause the vibration and noise of the planetary gear set. In this paper, a dynamic model is developed to study the influence of the sliding friction on the dynamic characteristics of the planetary gear set by including the time-varying mesh stiffness(TVMS), sliding friction forces and...

Time-varying mesh stiffness (TVMS) is an important excitation source of a planetary gear set. Sliding friction and spalling defects have significant effect on the TVMS. Accurate evaluation of the TVMS can help obtain the vibration characteristics and further detect the spalling defects of the planetary gear set. In this paper, an improved analytica...

Wear commonly occurs in planetary gear transmission systems. Fundamentally, the tooth wear could cause tooth profile deviation, which would increase the vibration and noise of gearbox. In order to monitor and forecast the wear condition of gears via vibration-based methods, it is necessary to establish the dynamics model of a planetary gear set wit...

Active vibration control using electrohydraulic shaking table (EHST) system is widely applied in civil engineering, automotive industry, environmental vibration testing and other situations where large actuating forces are needed. However, the electrohydraulic actuators (actuating systems) often suffer from drawbacks of limited frequency bandwidth,...

Motivated by our recent research presenting the effect of dry oxidation on crack propagation of Si nanofilm, water environment was taken into account in this work to clarify how crack propagates accompanied by initial wet oxidation which is influential for nanoscale devices in aqueous environment. By Reactive force field molecular dynamics (ReaxFF...

In machining process, cutting forces are difficult to measure accurately due to the dynamic characteristic of measurement system. The cutting forces compensation requires the frequency response function (FRF), which cannot be measured in actual production. This paper proposes an effective method for FRF modelling and calculating based on transfer p...

Impact force identification remains a challenging inverse problem, where a small error in structural responses may lead to a large deviation in the actual solution. Recently, sparse regularization has attracted a lot of interest in the field of force identification. However, the standard sparse regularization method for force identification does no...

Dynamic milling forces have been widely used to monitor the condition of the milling process. However, it is very difficult to measure milling forces directly in operation, particularly in the industrial scene. In this paper, a dynamic force identification method in time domain, conjugate gradient least square (CGLS), is employed for reconstructing...

The standard sparse regularization method based on l1-norm minimization for impact force identification has already proved to be an interesting alternative to the classical regularization method based on l2-norm minimization. However, choosing the l1-norm as a convex relaxation of the l0-norm, the corresponding sparse regularization model generally...

Active vibration control of large laminated cylindrical structures, for example, the cabin of space, air, surficial or subaqueous vehicles, usually requires multiple inputs and multiple outputs to the system, since there are usually multiple vibration sources and each source contains multiple frequency components. The performance of multiple inputs...

Impact force identification plays an important role in structural health monitoring, dynamics optimization design, milling force measurement, etc. However, the traditional L2 norm-based regularization methods run into the bottleneck and limitation on identification accuracy, stability, computational efficiency, parameter selection, etc. Sparse regu...

The most common and effective way of rotating machinery diagnostics is to extract fault impact features from the vibration signals and to carry out further processing. As for planetary gear sets, because of the simultaneous mesh of multiple gears and the effect of the carrier rotation, the fault features are submerged in the strong harmonic signals...

Ultrasonic guided wave is a promising tool for structural health monitoring and nondestructive testing. Numerous signal processing methods have been proposed to detect and localize anomalies based on ultrasonic guided waves for plate-like structures. However, imaging performance is limited in these methods, such as large spot size and significant a...

Bearing faults are one of the most common inducements for machine failures. Therefore, it is very important to perform bearing fault diagnosis reliably and rapidly. However, it is fundamental but difficult to extract impulses buried in heavy background noise for bearing fault diagnosis. In this paper, a novel adaptive enhanced sparse period-group l...

Milling forces are important signals that can be used to monitor the condition of machine operating and milling process. In general, milling forces can be measured by special equipment, for example, Kistler dynameters. However, dynameters are very expensive and require particular geometry of workpiece, which causes that dynameters are limited in re...

Machinery fault diagnosis has progressed over the past decades with the evolution of machineries in terms of complexity and scale. High-value machineries require condition monitoring and fault diagnosis to guarantee their designed functions and performance throughout their lifetime. Research on machinery Fault diagnostics has grown rapidly in recen...

Regularization methods should be developed to overcome the ill-posedness of inverse problem of structural dynamic load identification for getting a stable solution. The conjugate gradient least squares (CGLS) iterative regularization algorithm has several advantages over direct regularization methods such as the Tikhonov method on solving inverse p...

The two-dimensional Hermitian interpolation wavelet is constructed by using the tensor product of the modified Hermitian wavelets expanded at each coordinate. Then the two-dimensional Hermitian interpolation wavelet is substituted into finite element formulations to address the wave propagation and load identification problems. Hermitian wavelet fi...

A new Hermitian Mindlin plate wavelet element is proposed. The two-dimensional Hermitian cubic spline interpolation wavelet is substituted into finite element functions to construct frequency response function (FRF). It uses a system’s FRF and response spectrums to calculate load spectrums and then derives loads in the time domain via the inverse f...

Force identification remains a challenging inverse problem, where a small error in structural responses may lead to a large deviation in the true solution. To overcome the ill-posed nature, a general sparse representation model is developed thereafter for solving the inverse problem of force identification. Different from the traditional function e...

The classical function expansion method based on minimizing l2-norm of the response residual employs various basis functions to represent the unknown force. Its difficulty lies in determining the optimum number of basis functions. Considering the sparsity of force in the time domain or in other basis space, we develop a general sparse regularizatio...

Vibration is the main factor influencing the stable operation of mechanical equipment. Malfunction in large mechanical equipment is always attributed to excessive vibration. Active control plays a key role in vibration optimization and secures the safe operation of mechanical equipment. However, the current active control methods mainly focus on op...

Force identification is a classical inverse problem, in which the measured data and the mathematical models of mechanical structures are used to determine the applied force. However, the identified force may seriously diverge from the true solution due to the unknown noise contaminating the measured data and the inverse of the ill-posed transfer ma...

The accurate real-time characterization of impact event is vital during the life-time of a mechanical product. However, the identified impact force may seriously diverge from the real one due to the unknown noise contaminating the measured data, as well as the ill-conditioned system matrix. In this paper, a regularized cubic B-spline collocation (C...

The aim of vibration isolation for rotating machinery is to reduce the energy from the vibration source through transfer paths into the receiver structure. However, the direct measurement of energy characteristics that have been thoroughly researched in theory and numerical simulation is always difficult to implement. In this paper, power flow comb...

Accuracy and efficiency are significant factors in wave propagation and load identification of mechanical structure. By introducing modified Hermitian cubic spline wavelets on interval (HCSWI), a multi-scale wavelet-based numerical method is proposed. The present method can avoid the boundary problem of the original Hermitian interpolation wavelet....

For force identification, the solution may differ from the desired force seriously due to the unknown noise included in the measured data, as well as the ill-posedness of inverse problem. In this paper, an efficient basis function expansion method based on wavelet multi-resolution analysis using cubic B-spline scaling functions as basis functions i...