Fangsen Cui

• Ph D
• Principal Scientist at Agency for Science, Technology and Research (A*STAR)

The invention relates to an endovascular stent comprising a tubular expandable lattice structure comprising a plurality of negative Poisson' s ratio (NPR) cells in connection with at least one row of positive Poisson's ratio (PPR) cells provided along a length of the stent. Each NPR cell may have a shape of a re-entrant (RE) hexagon. The stent may...

Purpose To investigate local hemodynamic changes resulting from elevated intraocular pressure (IOP) in different vasculature networks using a computational fluid dynamics model based on 3D reconstructed confocal microscopic images. Methods Three-dimensional rat retinal vasculature was reconstructed from confocal microscopy images using a 3D U-Net-...

In this paper, soliton solutions, lump solutions, breather solutions, and lump-solitary wave solutions of a (2+1)-dimensional variable-coefficient extended shallow-water wave (vc-eSWW) equation are obtained based on its bilinear form. By calculating the vector field of the potential function, the interaction between lump waves and solitary waves is...

The sparse defect imaging using guided waves for pipe structures has attracted a lot of attention due to its intuitive way of defect localization. However, there exist few attempts to employ the Lp norm (p < 1) in sparse imaging to improve imaging performance. In this study, a new sparse imaging method based on Bayesian hierarchical hyper-Laplacian...

In densely populated cities, residents living near aerodromes may experience heightened exposure to aircraft noise. With hybrid work arrangement, authorities have observed a rise in the number of complaints filed by residents affected by aircraft noise. In view of this problem, urban planners are now placing even more emphasis on exploring solution...

The present research focusses on estimating the elastic constants of orthotropic laminates using ultrasonic guided waves (GWs) excited through Lead Zirconate Titanate (PZT) sensors and sensed using one-dimensional laser vibrometer. The elastic constants of a material are crucial for understanding its mechanical behaviour and are typically determine...

Previous studies have demonstrated the superior damage identification performance of the double-window principal component analysis (DWPCA) method over traditional PCA methods and other traditional techniques, such as wavelet and regression analysis. DWPCA uses temporal windows to discriminate structural states and spatial windows to exclude damage...

The treatment of fractured bones is crucial for the recovery of injuries during the healing process of femur fractures. Both qualitative and quantitative analyses are critical in the treatment of fractured bones. The healing process of femur fractures can be regarded as the reverse process of its damage degradation. This paper presents a qualitativ...

Rayleigh waves are successfully employed for the characterization of surface defects through the utilization of both time and frequency domain analysis. However, a significant challenge arises when attempting to cover a broad range of the defect depth to Rayleigh wavelength ratio with a single method. This paper presents an enhanced methodology tha...

To develop sustainable cities, natural ventilation is being explored as one of the ways to reduce energy consumption and carbon dioxide emissions. Recently, acoustic metamaterials with ventilation have garnered attention for their potential to provide both ventilation and noise control. In addition, this class of acoustic metamaterials can be used...

Thermographic inspection is considered an effective and promising nondestructive testing tool because of its intuitiveness, wide range and noncontact property. Despite this, the detection of weak defects and the recovery of their shape remain difficult, particularly when the surface being inspected is the opposite of the surface being drilled. This...

The flexibility and controllability of 3D printing technologies have made them popular for creating integrated wearable sensors. However, producing sensors with 3D anisotropic response is still difficult with current printing materials and techniques. To address this challenge, digital light process (DLP) printing technology with blading function t...

The visceral hybrid procedure combining retrograde visceral bypass grafting and completion endovascular stent grafting is a feasible alternative to conventional open surgical or wholly endovascular repairs of thoracoabdominal aneurysms (TAAA). However, the wide variability in visceral hybrid configurations means that a priori prediction of surgical...

Zero-group-velocity (ZGV) Lamb waves are usually excited and detected using non-contact laser ultrasonic systems, as contact techniques such as using conventional bulky discrete piezoelectric transducer may cause interferences and errors in identifying the ZGV Lamb waves due to the large mass and stiffness introduced. Nevertheless, contact transduc...

Guided wave (GW)-based techniques have been extensively investigated and applied in material characterization, damage detection, and structural health monitoring. A comprehensive understanding of GW is the cornerstone for the development of such techniques. Based on the semi-analytical finite element (SAFE) method, an open-source dispersion calcula...

A bridge vibration measurement method by Unmanned Aerial Vehicles (UAVs) based on a Convolutional Neural Network (CNN) and Bayesian Optimization (BO) is proposed. In the proposed method, the video of the bridge structure is collected by a UAV, then the reference points in the background of the bridge and the target points on the bridge in the video...

As sustainability is one of the main pillars in developing future cities, adopting natural ventilation whenever possible is one way to reduce energy consumption, thus indirectly reducing carbon dioxide emissions. Lately, ventilated acoustic metamaterials have started to receive more research attention because of how they can provide both ventilatio...

Complications of thoracic endovascular aortic repair are closely related to the mechanical properties of implanted stent-grafts. Compared with straight vessels, the complex morphology of aortic arch imposes strict requirements on stent-graft properties. This study designed and verified an aortic stent-graft by optimizing a specially constructed com...

Accurate measurement of the material parameters of composite in a nondestructive manner is of great significance for evaluating mechanical performance. This study proposes to use a genetic algorithm (GA) to reconstruct the stiffness matrix of carbon fiber reinforced polymer (CFRP) with array-guided wave (GW)-based GA. By comparing the numerically c...

A convolutional neural network (CNN)-based structural damage detection (SDD) method using populations of structures and modal strain energy (MSE) is proposed. In this study, sufficient samples of the CNN are provided by numerical simulations, and the size of the model can be changed by modifying the coordinates of some nodes, thereby establishing a...

The defect imaging based on guided wave provides an intuitive way for defect localization. Recently, sparse representation methods based on the damage sparsity assumption have been developed for defect imaging, where few sensors are used in these methods. However, these sparse imaging methods need repeatedly tuning the regularization parameter to o...

Guided waves (GW) are massively used for structural health monitoring and defect evaluation in plate, pipe, and rail structures. To accurately and efficiently calculate the dispersive natures of GW in complex waveguides, this study proposes a novel Gauss–Lobatto–Legendre-based high-order semi-analytical finite element method (GLL-SAFE). Combining t...

The COVID-19 pandemic has greatly changed workplace management. Most workplaces have adopted the work-from-home policy to minimize the risk of community spread. Consequently, housing estates remain largely occupied during office hours. Since some housing estates are situated in the vicinity of an airport, noise pollution resulted from the takeoff a...

Owing to the COVID-19 pandemic, remote work has been widely adopted as one of the safe management measures at workplaces. The rapid advancement in communications technology has enabled work to still be delivered efficiently and effectively through virtually. With remote work being a norm in workplace management, housing estates are expected to rema...

Pavement defect detection is critical for pavement maintenance and management. Meanwhile, the accurate and timely detection of pavement defects in complex backgrounds is a huge challenge for maintenance work. Therefore, this paper used a mask region-based convolutional neural network (Mask R-CNN) and transfer learning to detect pavement defects in...

Carbon fiber reinforced polymer (CFRP) composites are increasingly used in aerospace, automobile, marine and power industries due to its good mechanical strength and low material density. The defect detection in CFRP has been challenging because of their complex material configuration and various types of defects. In this paper, we reported the use...

This study proposes a structural damage recognition method based on the filtered feature selection (FFS) and the convolutional neural network (CNN). The FFS usually provides a better sample feature input for a CNN, avoiding the problem that the CNN is prone to over-fitting for the data containing a large amount of invalid feature information. To de...

A covered stent has been used to treat carotid artery stenosis to reduce the chance of embolization, as it offers improved performance over bare-metal stents. However, membrane infolding of covered stents can affect efficiency and functionality for treating occlusive disease of first-order aortic branches. In order to mitigate the degree of infoldi...

Surface-breaking cracks are typical defects in tubular structures. Compared with other types of defects such as internal voids, surface cracks often impose more serious threats to structural integrity. This study presents an approach to detect and characterize surface-breaking cracks on tubular samples through the use of ultrasonic phased array tec...

The use of carbon fiber reinforced polymer (CFRP) composites is gaining popularity in various industries. Due to its anisotropic nature, the characterization of the mechanical properties of CFRP is challenging. The current practices for determination of the elastic properties of CFRP materials are through destructive testing methods, which is not f...

Fatigue cracks initiated from fastener holes are common in aircraft structures. Implementation of effective structural health monitoring (SHM) system to detect or monitor fatigue cracks near fastener holes is desired for realizing condition-based maintenance with improved aircraft safety at reduced cost. In this work, direct-write piezoelectric ult...

The present study focuses on investigating the structural integrity of rail track sections of the high-speed railways using the Rayleigh waves generated and sensed using a fully non-contact optical Laser system. The raw broadband beam of the excitation laser was converted to a narrowband beam using a customized optical system, whereas the propagati...

Current generation of bioresorbable coronary scaffolds (BRS) posed thrombogenicity and deployment issues owing to its thick struts and overall profile. To this end, we hypothesize that the use of nanocomposite materials is able to provide improved material properties and sufficient radial strength for the intended application even at reduced strut...

Thoracic endovascular aortic repair (TEVAR) is limited by the complicated anatomy of an aortic arch. This study proposed a new stent-graft (SG) design with slits that can positively improve the sealing effect between the aorta and SG while maintaining blood flow to supra-aortic branches. Firstly, a new SG was designed by changing the geometrical pa...

The guided wave is an efficient and reliable tool for the structural health monitoring (SHM) of the composite laminates. In the guided wave-based SHM methods, extracting the dispersion curves is essential for integrity evaluation. In this study, a sparse wavenumber analysis based on hybrid least absolute shrinkage and selection operator (Lasso) reg...

Non-anatomical placement may occur during the surgical implantation of the meniscal implant, and its influence on the resulting biomechanics of the knee joint has not been systematically studied. The purpose of this study was to evaluate the biomechanical effects of non-anatomical placement of the meniscal implant on the knee joint during a complet...

Bonded structures are frequently adopted in structural connections and are highly prone to degradation or decrease of interfacial strength due to adhesive aging, poor quality of surface preparation, as well as the exposure to harsh environment and external loading. This study addresses the establishment of a framework in which a modally selective u...

Crucial factors in window performance, such as natural ventilation and noise control, are generally conceived separately, forcing users to choose one over the other. To solve this dualism, this study aimed to develop an acoustic metamaterial (AMM) ergonomic window design to allow noise control without dependence on the natural ventilation duration...

The present study aimed to design and optimize thoracic aorta stent grafts (SGs) based on the influence of geometric parameters on flexibility and durability. Five geometric parameters were selected, including strut height, strut number, strut radius, wire diameter, and graft thickness. Subsequently, 16 finite element (FE) models were established w...

Based on the fully deployed space beam-like truss, the vibration reduction of the lattice structure is studied by using the local NES (nonlinear energy sink) attachment in this paper. The beam-like lattice structure is modeled as an equivalent linear continuous system (a finite length beam) by the equivalent method and validated with the finite ele...

This paper presents a homography-based method by combining an unmanned aerial vehicle (UAV) and the digital image correlation (DIC) together for vibration measurement of a bridge model. The videos of the bridge model captured by the UAV can be analyzed by the DIC method to track the displacement of the measurement points. Direct use of measured vid...

Disbond defect is a critical concern for the integrity of adhesively bonded engineering structures, and its characterization using ultrasonic guided waves (UGW)-based methods, suffers from the contradiction of multiple wave modes co-excitation at high frequency and poor sensitivity at low frequency. With this concern, this study addresses an invest...

In this paper, the nonlinear dynamic analysis of the circular truss equivalent to the cylindrical shell under the influence of the thermal excitation and the damping coefficient are studied. The annular truss structure is equivalent to the cylindrical shell structure based on the previous equivalent process, and the nonlinear dynamic equations of t...

The research on acoustic metamaterials (AMMs) has progressed rapidly over the last decades. One of the applications is for noise control and airflow in duct-like systems. These are useful features for natural ventilation window design; however, the visual impact between indoor and outdoor environment, as another key factor of windows, makes the exi...

In an adhesively bonded structure, utilizing the adhesive itself for monitoring the joint integrity can be beneficial in reduction of labor, time, and potential human errors while avoiding problems associated with introduction of a foreign sensor component. This work started from the examination of effective piezoelectricity of commercial structura...

The instantaneous speed (IS), i.e. instantaneous frequency, is an important feature to exploit the time-frequency characteristic of nonstationary signals. The IS estimation is widely used in various fields of signal processing. The IS estimation can also be regarded as a useful tool for rotating machinery fault diagnosis under nonstationary conditi...

The traditional methods of structural health monitoring (SHM) have obvious disadvantages such as being time-consuming, laborious and non-synchronizing, and so on. This paper presents a novel and efficient approach to detect structural damages from real-time vibration signals via a convolutional neural network (CNN). As vibration signals (accelerati...

Ventilation window is one of the critical elements in sustainable building development, although frequently, outdoor factors such as environmental noise can limit their use. It is necessary to develop windows with both natural ventilation and noise mitigation functions. Acoustic Metamaterials (AMMs) set a new trend in solving physical challenges re...

This paper aims to locate damaged rods in a three-dimensional (3D) steel truss and reveals some internal working mechanisms of the convolutional neural network (CNN), which is based on the first-order modal parameters and CNN. The CNN training samples (including a large number of damage scenarios) are created by ABAQUS and PYTHON scripts. The mode...

Currently available finite element (FE) models of intertrochanteric fractures cannot accurately represent the real material properties of femurs. This paper aimed to create and validate an FE model of intertrochanteric fractures with inhomogeneous material properties assigned from CT images by a node-based approach. The geometry of a femur was auto...

To select animals of appropriate size for preclinical studies of cardiovascular devices, reference knowledge of the cardiovascularanatomy relative to body weight is crucial. We measured the luminal diameters of the arteries (carotid, femoral, and iliac arteries) that are the common access vessels for endovascular and vascular procedures in Yorkshir...

Membrane-type acoustic metamaterials (MAM) are novel, lightweight and compact materials that can be used to isolate the sound at low frequencies beyond the limits of conventional materials. MAMs open up many possibilities for creating a new generation of acoustic materials and sensor devices. In this paper, the acoustic-structural interaction of th...

A composite cantilever plate model with variable high speed rotating blade subject to transverse aerodynamic force and centrifugal force is established. Based on the third-order shear deformation theory, von Karman large deformation theory and Hamilton's principle, the nonlinear partial differential governing equations of motion are established for...

A multi-frequency ultrasonic method was proposed to detect and characterize delamination and rich resin in thick composites with waviness. Addressing the challenges for ultrasonic inspection caused by waviness, multi-layer structure, and multiple defect types, ultrasound propagation in thick wavy composite was investigated through a dedicated numer...

Our group is developing novel preferential covered carotid stents aimed at preventing friable parts from atherosclerotic plaques from dislodging into the cerebral blood flow, and also preserving external carotid artery (ECA) perfusion through slits on the membrane. Enhanced ECA flow rates can be achieved by designing bare metal stents with larger c...

Adhesive bonded joints are frequently adopted in structural applications. The adhesive aging, low quality of surface preparation, as well as the exposure to external harsh environment and loading, may degrade the quality of adhesive, leading to disbond and decrease of the interfacial strength of the bonded joints. This study addresses both numerica...

This experimental study systematically examines the effect of slurry composition on the microstructure and mechanical properties of open-cell foams, by altering the binder concentration and powder loading of SS316L slurries used in the template replication foam fabrication. The slurry and foam morphologies were observed by Scanning Electron Microsc...

Transrectal ultrasound (TRUS) guided needle biopsy is currently the clinical routine for diagnosis of prostate cancer. Due to the blurry TRUS imaging, magnetic resonance imaging (MRI) of prostate is usually taken prior to the biopsy procedure to assist needle target planning. In this paper, a novel geometric transformation method, which is based on...

Thick composites are increasingly applied in aerospace engineering and prone to out-of-plane waviness in the manufacturing process. Besides the drastic decrease of compressive strength due to out-of-plane waviness, locally rich resin regions may also exist in the composite, both perplexing the ultrasound propagation therein. In this study, a multi-...

Thoracic aortic aneurysm (TAA) is a severe cardiovascular disease with a high mortality rate, if left untreated. Clinical observations show that aneurysm growth can be linked to undesirable hemodynamic conditions of the aortic aneurysm. In order to gain more insight on TAA formation, we developed a computational framework in vitro to investigate an...

Based on the classification ability of a convolutional neural network (CNN), this paper proposes a structural damage detection method in which a CNN is used to classify the location and level of damage in a structure. The dynamic responses are combined with the modal parameters of the structure as the inputs to the CNN to detect the damage. As stru...

Bare metal stenting (BMS) does not adequately address the atheroembolic characteristic of carotid artery stenosis. While simple covered stents (CS) may prevent dislodged fragments of the atherosclerotic plaque from entering the blood stream, they also block blood flow into the major branches of the artery alongside the lesion, which is not desirabl...

Stenting of curved arteries is more challenging than straight vessels. There has been an increasing need for new techniques to treat lesions in highly curved locations. One generic idea is to use curved stents to treat lesions in such curved locations. Computational modeling of straight stent crimping which is being used to evaluate the structural...

The development of windows which can address the issue of high noise levels while maintaining natural ventilation has drawn significant attention recently. However, there are limitations to traditionalouble glazing together with duct designs. Previously, window systems have been developed based on the local resonant stopband of acoustic metamateria...

In this paper, a convolutional neural network (CNN) was used to extract the damage features of a steel frame structure. As structural damage could induce changes of the modal parameters of the structure, the convolution operation was used to extract the features of modal parameters, and a classification algorithm was used to judge the damage state...

To improve window performances in reducing noise and allowing for air exchange, most current approaches focus on techniques such as double glazed and ducted designs, generally leading to bulky designs, visually non-optimised, and with narrow-banded frequency. In this research, window systems based on acoustic metamaterials (AMMs) are developed, and...

Purpose The purpose of this paper is to demonstrate the feasibility of using shape memory polymer (SMP) for developing vascular stent. In particular, the expansion performance is analyzed through extensive modeling and simulation. Design/methodology/approach Firstly, the authors construct the model geometry and propose a constitutive model to descr...

Carotid artery stenosis can be treated by carotid endarterectomy operations (CEA) and carotid artery stenting procedures (CAS). Unlike other artery stents, the effectiveness and safety of carotid artery stenting is not prevailing though it has many advantages. Our group has been developing new generation carotid artery stent since 2011. The innovat...

Here, a prototypical metallic nanoglass is proposed as a new alloy for balloon expandable stents. Traditionally, the stainless steel SS 316L alloy has been used as a preferred material for this application due to its proper combination of mechanical properties, corrosion resistance, and biocompatibility. Recently, metallic glasses (MGs) have been c...

Thoracic endovascular aortic repair (TEVAR) has been introduced as a less invasive approach to the treatment of thoracic aortic aneurysm (TAA). However, the effectiveness of TEVAR in the treatment of TAA is often limited due to the complex anatomy of aortic arch. Flow preservation at the three supra-aortic branches further increases the overall tec...

Conventional sound barriers are constrained by fixed geometry which results in many limitations. In this research, origami, the paper folding technique, is exploited as a platform to design deployable and reconfigurable sound barriers, as well as to actively tailor the attenuation performance. As a proof of concept, a three-dimensional barrier stru...

This study investigates into the sound transmission through a periodic acoustic metamaterial grating of finite size. The single-layer grating is constructed by periodically arranging sub-wavelength unit cells in a slab, as a part of a large baffle between two acoustic domains. The metamaterial unit cell consists of an open duct decorated with coile...

To design a hooked self-expandable caval valve stent and determine the best crimping scenario for its percutaneous implantation in the Superior and Inferior Vena Cava (SVC & IVC) for the treatment of tricuspid regurgitation (TR). A hooked, Nitinol based stent design was modeled using SOLIDWORKS and finite element analysis (FEA) was carried out usin...

Manmade debris and natural meteoroids, travelling in the Low Earth Orbit at a speed of several kilometers per second, pose a severe safety concern to the spacecraft in service through the HyperVelocity Impact (HVI). To address this issue, an investigation of shock Acoustic Emission (AE) waves induced by HVI to a downscaled two-layer Whipple shieldi...

Noise pollution has a significant negative effect on psychological health and quality of life. The building envelop, particularly windows often constitute to the primary path for external noise sources to travel into the buildings. Here we have designed and fabricated transparent piezoelectric film speakers as secondary area sound source for active...

Clotting of blood elements or intraluminal thrombus (ILT) is known to develop within aortic aneurysm sacs, and is clinically associated with the dilation and rupturing of aneurysms. However, the underlying factors that generate ILT are still unclear. We hypothesize that ILT can form under the influence of unfavorable hemodynamic patterns. This pape...

Functional and mechanical properties of novel biomaterials must be carefully evaluated to guarantee long-term biocompatibility and structural integrity of implantable medical devices. Owing to the combination of metallic bonding and amorphous structure, metallic glasses (MGs) exhibit extraordinary properties superior to conventional crystalline met...

Ultrasonic guided waves (GWs) are being extensively investigated and applied to nondestructive evaluation and structural health monitoring. Guided waves are, under most circumstances, excited in a frequency range up to several hundred kilohertz or megahertz for detecting defect/damage effectively. In this regard, numerical simulation using finite e...

The study of ventilation windows for both natural ventilation and noise mitigation has drawn significant attention recently. This paper presents the numerical approaches to analyse the integrated thermal and acoustical performance of ventilation windows, for a residential building in tropical climate which employs double-layer noise mitigation wind...

The current study investigates the acoustic absorption property of nickel-based superalloy open-cell foams manufactured by a newly developed template replication process. Inconel 625 open cell foams with controllable porosities (92%–98%) and cell sizes (300 μm–900 μm) have been successfully produced and tested for their sound absorption performance...

Aiming to design building façade with both natural ventilation and noise insulation per-formance, we propose an acoustic metasurface (AMS) by scaling up structured unit cells in a planar array. Each unit cell is in the shape of a short acoustic duct lined with periodic sub-chamber scatters. Acoustic stop-band exists in the periodic structure mainly...

Aiming to design building façade with both natural ventilation and noise insulation per-formance, we propose an acoustic metasurface (AMS) by scaling up structured unit cells in a planar array. Each unit cell is in the shape of a short acoustic duct lined with periodic sub-chamber scatters. Acoustic stop-band exists in the periodic structure mainly...

The study of ventilation windows for both natural ventilation and noise mitigation uses has drawn attention recently. It is challenging to design and evaluate the window performance by means of modelling and simulation. Here we present the numerical approaches to analyse and predict the thermal and acoustical performances of different window design...

Artificial meniscal implants may replace severely injured meniscus and restore the normal functionality of the knee joint. Implant material stiffness and shape influence the longevity of implantations. This study, using 3D finite element analysis, aimed to evaluate the effects of material stiffness variations of anatomically shaped artificial menis...

Full papers for Symposium K

Though biomechanical methods have been proposed to assess the healing status of fractured bones for more than two decades, the effective stiffnesses obtained theoretically never match the experimentally measured results for the healing progression. This paper proposed a novel numerical model, the simulation results of which are able to reflect the...

Hypervelocity impact (HVI), ubiquitous in low Earth orbit with an impacting velocity in excess of 1 km/s, poses an immense threat to the safety of orbiting spacecraft. Upon penetration of the outer shielding layer of a typical two-layer shielding system, the shattered projectile, together with the jetted materials of the outer shielding material, s...