W. D. Zhu

University of Maryland, Baltimore County | UMBC · Department of Mechanical Engineering

A novel image-based long-range continuously scanning laser Doppler vibrometer (CSLDV) is developed to measure vibration of a rotating structure with a complex background. The image-based long-range tracking CSLDV can track and scan the rotating structure by processing its images captured by a camera in the image-based long-range tracking CSLDV. A n...

Tensegrity structures become important components of various engineering structures due to their high stiffness, light weight, and deployable capability. Existing studies on their dynamic analyses mainly focus on responses of their nodal points while overlook deformations of their cable and strut members. This study proposes a non-contact approach...

Pipe-type cable systems, including high-pressure fluid-filled (HPFF) and high-pressure gas-filled cables, are widely used for underground high-voltage transmission. These systems consist of insulated conductor cables within steel pipes, filled with pressurized fluids or gases for insulation and cooling. Despite their reliability, faults can occur d...

Large deployable mesh reflectors are essential for space applications, providing precise reflecting surfaces for high-gain antennas used in satellite communications, Earth observation, and deep-space missions. During on-orbit missions, active shape adjustment and attitude control are crucial for maintaining surface accuracy and proper orientation f...

Pipe-type cable systems, including high-pressure fluid-filled (HPFF) and high-pressure gas-filled (HPGF) cables, are widely used for underground high-voltage transmission. These systems consist of insulated conductor cables within steel pipes, filled with pressurized fluids or gases for insulation and cooling. Despite their reliability, faults can...

A tidal current energy converter (TCEC) is a device specifically designed to harness the kinetic energy present in tidal energy and convert it into stable mechanical rotational energy, which can then be used to generate electricity. The core component of the TCEC is an infinitely variable transmission (IVT), which adjusts the speed ratio to maintai...

This study focuses on coupled vibrations of rotating thin-walled composite beams subjected to hygrothermal effects. In the existing literature, many studies have been conducted on coupled bending-torsional vibration and resonance in hygrothermal environments. Few studies considered the coupled flapwise-edgewise and resonances of composite thin-wall...

A dynamic pitch strategy is usually adopted to improve the aerodynamic performance of the blade of a wind turbine. The dynamic pitch motion will affect the linear vibration characteristics of the blade. However, these influences have not been studied in previous research. In this paper, the influences of the rigid pitch motion on the linear vibrati...

The suspension system is an important part of a vehicle and directly affects the vehicle's comfort and stability during driving. There are various nonlinearities and uncertainties in the vehicle suspension system, and even small changes can have a significant impact on the suspension performance. This paper provides an in-depth study of quarter- an...

Planetary gear train is an important part of automatic transmission. The oil film between teeth is one of the key factors affecting the torsional vibration of planetary gear train. Selecting the appropriate oil film stiffness is of great significance for analyzing the nonlinear dynamic characteristics of planetary gear train. A method for analyzing...

Developing a miniatured laser vibrometer becomes important for many engineering areas, such as experimental and operational modal analyses, model validation, and structural health monitoring. Due to its compact size and light weight, a miniatured laser vibrometer can be attached to various mobilized platforms, such as an unmanned aerial vehicle and...

This study presents a flume flow experimental investigation of operational performances of a tidal current energy converter (TCEC) with a horizontal-axis tidal turbine and an infinitely variable transmission (IVT). A closed-loop speed ratio controller of the IVT is developed to continuously adjust its speed ratio with variable water speeds for a de...

Fatigue failures at fastener holes in structures are undesirable as they can lead to catastrophic mechanical failures. Interference pins create interference fits with joined components to reduce stresses around fastener holes and extend the fatigue life of a structure. In this research, a novel method for finite element (FE) modeling of interferenc...

This paper presents the design and optimization of a cable-driven parallel polishing robot (CDPPR) with kinematic error modeling and introduces an improved non-dominated sorting genetic algorithm II (NSGA-II) for multi-objective optimization. First, the mechanical design and kinematic and static modeling of the CDPPR are conducted. Subsequently, a...

Natural vibration characteristics of a cantilever beam that is parametrically excited by pitch motion are theoretically investigated in this work. A partial differential equation governing the parametrically excited bending vibration of the beam is established by employing the generalized Hamiltonian principle. Normal modal functions of the bending...

Introduction Dental implantation has emerged as an efficient substitute for missing teeth, which is essential for restoring oral function and aesthetics. Compared to traditional denture repair approaches, dental implants offer better stability and sustainability. The position, angle, and depth of dental implants are crucial factors for their long-t...

This paper proposes a novel numeric tooth contact model of hypoid gears which combines the conjugate approach and a special method of contact search operations. The model performs the tooth contact analysis at different contact curvatures, and demonstrates better computational accuracy than the finite element method. The model is capable of quickly...

The seismic response is a critical aspect of structural engineering, as it directly influences the design and safety evaluation of such systems. Structural seismic response becomes more complicated when unavoidable uncertainties in the structure are considered. Therefore, solving and analyzing the stochastic dynamic response of structures efficient...

Quasi-periodic solution of a damped quasi-periodic (QP) Mathieu’s equation with cubic nonlinearity is obtained by using the incremental harmonic balance (IHB) with two time scales. It is found that the QP equation consists of stable and unstable QP solutions and every solution consists of carrier frequencies and their spaced uniformly sidebands. Th...

Aero-engine rotor system contains a variety of connectors such as bolts and bearings. However, the dynamic behaviors of the connection are complex in actual engineering. In this paper, the dynamic behavior of the rotor-bearing system with bolted joints and the influence of the parameters of the joints on it are clarified. The parameters include the...

As rigid robots suffer from the higher inertia of their rigid links, cable-driven parallel robots (CDPRs) are more suitable for large-scale three-dimensional (3D) printing tasks due to their outstanding reconfigurability, high load-to-weight ratio, and extensive workspace. In this paper, a parallel 3D printing robot is proposed, comprising three pa...

A novel general-purpose three-dimensional (3D) continuously scanning laser Doppler vibrometer (CSLDV) system was recently developed by the authors to measure 3D vibration of a structure with a curved surface. As a non-contact system, it can avoid the mass-loading problem in 3D vibration measurement using triaxial accelerometers. In previous studies...

A novel demodulation method with a reference signal is developed for operational model analysis of a beam structure under a random excitation. The novel demodulation method can process measurements of the beam by a continuously scanning laser Doppler vibrometer (CSLDV) system and measurements of a reference point on the beam by a single-point laser...

Aeroengines are usually designed with a dual-rotor configuration for the rotating part. A dual-rotor system has coupling characteristics introduced by an inter-shaft bearing, and the rotating direction of the rotors has critical influences on the performance. It becomes more complicated when the inevitable uncertainties of the dual-frequency excite...

Dental implantation has emerged as an efficient substitute for missing teeth, which is essential for restoring oral function and aesthetics. Compared to traditional denture repair approaches, dental implants offer better stability and sustainability. The position, angle, and depth of dental implants are crucial factors for their long-term success a...

This paper investigates the vibration of an axially moving string with symmetrical nonclassical boundary conditions subjected to harmonic excitation. Instead of conventional fixed boundary, the boundary is modeled as a combination of a damper, a linear stiffness, and a cubic nonlinear stiffness to study the first primary resonance of the axially mo...

A tidal current energy converter including an infinitely variable transmission (IVT) control system and a hybrid vertical axis wind (or water) turbine (VAWTs) apparatus. The hybrid VAWT apparatus includes a modified-Savonius (MS) rotor in the central region and a straight bladed H-type Darrieus rotor in the surrounding annular region. The IVT contr...

Experimental methods are used across all engineering domains to study a system’s response to some specified input or forcing function. This work explores the response of a structural member in a wind tunnel containing a cantilever plate attached to a cylinder, under an impact excitation. The computer-aided design (CAD) model and finite element anal...

A novel edge detection method is developed for an image-based tracking continuously scanning laser Doppler vibrometer (CSLDV) system to track a rotating structure without attaching any mark or encoder to it. The edge detection method can determine real-time positions of points on edges of the rotating structure by processing images captured by a ca...

This study develops a novel general-purpose 3D continuously scanning laser Doppler vibrometer (CSLDV) system to measure 3D full-field vibration of a turbine blade with a curved surface under random excitation and proposes an operational modal analysis (OMA) method to identify its modal parameters. The 3D CSLDV system developed in this study contain...

This work explores the response of a cantilever plate attached to a cylinder in a wind tunnel under an impact excitation. A detailed computer-aided design (CAD) model and the finite element analysis (FEA) modal simulation of the experimental setup are introduced. Two experimental techniques are thoroughly discussed: an accelerometer-based experimen...

In addition to the shared weights of the synaptic connections, our new neural network includes the synaptic effective range weights for both the forward and back propagation. We try to simulate the functions of prefrontal lobe, amygdala, and hippocampus by the Deep learning model of upstream and downstream brain regions(DLMOUADBR). Along the forwar...

This paper proposes a fuzzy proportion integration differentiation (PID) control strategy based on an adaptive whale optimization algorithm (FPID-AWOA) for trajectory tracking of a cable-driven parallel robot (CDPR). A mechanical prototype, and kinematic and dynamic models of the CDPR are established. Thus, new fuzzy rules are developed and a new f...

Demand on the analysis of a nonlinear system under multi-frequency harmonic excitations is commonly encountered in an engineering field, which requires a feasible analysis technique. The existing incremental harmonic balance method, however, shows an apparent deficiency in the calculation efficiency, due to the inappropriate rule of selecting frequ...

In addition to the shared weights of the synaptic connections, we proposed a new neural network that includes the synaptic effective range weights for both the forward and back propagation. We try to simulate the prefrontal lobe, amygdala, and hippocampus. Along the forward direction, the fear memory gradually increases. Along the direction of back...

The nonlinear dynamic behaviors of dual-rotor-bearing systems with looseness and rub–impact faults are discussed in this paper. The dual-rotor-bearing system with looseness and rub–impact coupling faults is established by the finite element method. The component mode synthesis (CMS) and proper orthogonal decomposition (POD) methods are introduced....

Temperature has significant effects on the modal parameters of a structure. In general, as the temperature increases, the natural frequencies of a structure decrease with the softening of mechanical properties of the material at high temperature. However, it can be found from some thermal modal experiments that the natural frequencies of a structur...

The forced transient vibration of a multi-cracked bridge model under moving loads is investigated in this work based on Green’s function method, and Euler–Bernoulli beam model is used to establish the dynamic model of the bridge. Parameters of a bridge are chosen based on civil engineering standards in this study, and moving loads correspond to rea...

Coating defect detection is a critical aspect of ensuring product quality in the manufacturing process. However, due to the variety of coating defects and the complex detection background in actual production, detecting these defects can be challenging. To improve the accuracy and robustness of coating defect detection, a coating defect detection m...

In addition to the shared weights of the synaptic connections, we proposed a new neural network that includes the synaptic effective range weights for both the forward and back propagation. And lots of simulations were used which RNN cannot be achieved. The simulations of PNN fit very well in experiments and hypotheses of 6 papers CNS Journals, 6 p...

As an abundant, clean, and predictable source of renewable energy, tidal current energy provides a cost-effective alternative to fossil fuels. Tidal current energy harvesting technologies are still at their early stages of development. Even some advanced demonstration projects with full-scale tidal current energy converters (TCECs) still face consi...

In light of recent advances in deep learning and Synthetic Aperture Radar (SAR) technology, there has been a growing adoption of ship detection models that are based on deep learning methodologies. However, the efficiency of SAR ship detection models is significantly impacted by complex backgrounds, noise, and multi-scale ships (the number of pixel...

Cable-driven parallel robots (CDPRs) have been widely used in engineering fields because of their significant advantages including high load-bearing capacity, large workspace, and low inertia. However, the impact of convergence speed and solution accuracy of optimization approaches on optimal performances can become a key issue when it comes to the...

In addition to the shared weights of the synaptic connections, we proposed a new neural network that includes the synaptic effective range weights for both the forward and back propagation. And lots of simulations were used which RNN cannot be achieved. The simulations of PNN fit very well in experiments and hypotheses of 6 papers CNS Journals, 6 p...

The present disclosure describes innovations to improve the use of noncircular gear pairs in a transmission, e.g., an infinitely variable transmission. The noncircular gear pair includes a first noncircular gear with a first pitch curve; and a second noncircular gear with a second pitch curve. The first pitch curve includes a plurality of elliptica...

A one-dimensional (1D) and two-dimensional (2D) scan scheme for a tracking continuously scanning laser Doppler vibrometer (CSLDV) system to scan the whole surface of a rotating structure excited by a random force. A tracking CSLDV system tracks a rotating structure and sweep its laser spot on its surface. The measured response of the structure usin...

Impact force identification is of great importance for composite structural health monitoring due to the poor impact resistance of composite materials. Convex sparse regularization method based on L 1 -norm tends to underestimate the amplitude of the impact force. This paper proposes a novel method using fully overlapping group sparsity based on L...

This paper proposes a non-intrusive technique based on the frequency normalisation for non-intrusive propagations of parameter uncertainties in nonlinear mechanical systems. The multi-solution dilemma found in resonance areas, which prohibits successful applications of uncertainty quantification methods, is alleviated by the additional normalised f...

A pipe-in-pipe (PIP) system is an important engineering structure in the petroleum industry. Under the excitation of ocean fluids, the PIP system produces vortex-induced vibration (VIV), which can affect the oil recovery efficiency of large offshore drilling platforms and cause various engineering accidents. In this work, a fluid-structure coupled...

In addition to the weights of synaptic shared connections, PNN includes weights of synaptic effective ranges [14-25]. PNN considers synaptic strength balance in dynamic of phagocytosing of synapses and static of constant sum of synapses length [14], and includes the lead behavior of the school of fish. Synapse formation will inhibit dendrites gener...

A temperature exceeding the safety threshold and excessive drilling force occurring during bone drilling may lead to irreversible damage to bone tissue and postoperative complications. Previous studies have shown that vibration-assisted drilling methods could have lower temperatures and drilling forces than those of the conventional drilling method...

In addition to the weights of synaptic shared connections, PNN includes weights of synaptic effective ranges [14-24]. PNN considers synaptic strength balance in dynamic of phagocytosing of synapses and static of constant sum of synapses length [14], and includes the lead behavior of the school of fish. Synapse formation will inhibit dendrites gener...

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...

A reduced-plate model transmission method is developed in this study to accurately and efficiently analyze the vehicle-pavement interaction dynamics over long travel distances. A wide pavement is reduced to many small areas (referred to as the reduced-plate models) along the vehicle-moving trajectory, and each reduced-plate model accounts for the v...

In addition to the weights of synaptic shared connections, PNN includes weights of synaptic effective ranges [14-24]. PNN considers synaptic strength balance in dynamic of phagocytosing of synapses and static of constant sum of synapses length [14], and includes the lead behavior of the school of fish. Synapse formation will inhibit dendrites gener...

This study proposes a novel general-purpose 3D continuously scanning laser Doppler vibrometer (CSLDV) system to measure 3D full-field vibration of a structure with a curved surface in a non-contact and fast way. The proposed 3D CSLDV system consists of three CSLDVs, a profile scanner, and an external controller, and is experimentally validated by m...

Tensegrity structures have experienced continued research and development interests in the past several decades. Revealing dynamic characteristics of a tensegrity structure, for example: vibration analysis, is an important objective in structural design and analysis. Traditional dynamic modeling methods are inaccurate in predicting dynamic respondi...

Periodic and period-doubling vibrations in a gear transmission system subjected to forced excitations with multi-piecewise linear functions are investigated in this work by using the incremental harmonic balance (IHB) method. The nonlinear ordinary differential equations that govern vibration of the gear transmission system are formulated by employ...

For vibration analysis of a tensegrity structure, the development of a dynamic model is a key step. A common issue in the traditional dynamic modeling methods for vibration analysis of tensegrity structures is that structural members are oversimplified. Member internal displacements, including those in longitudinal directions for bar and cable memb...

This paper provides wave solutions for the forced vibration response of a moving string system. Coupled vibration for different regions of the moving string system are considered. Firstly, due to the regularity of transmission and reflection, wave solutions are obtained by D’Alembert’s method incorporating forced waves. Secondly, the case of an app...