Dongsheng Zhang

• Professor
• Professor at Shanghai University

Fringe projection profilometry is a powerful tool that is widely applied to shape measurement of objects in engineering. Limited by the light intensity of the projection unit, this technique is difficult to be applied to surface inspection of large structures, especially in outdoor applications. In this study, a line laser source is selected as the...

To overcome the reliance on high-precision calibration plates in camera calibration, this paper proposes an extrinsic calibration method suitable for 3D-DIC in large field of view. The method combines image feature algorithms with DIC techniques to extract matching point pairs from the left and right images of binocular cameras. These matching poin...

Inspired by the composition of “hard” fin rays and “soft” collagen and the non-segmented and segmented composite structure of fish fins, we propose a partially segmented laminated structure design concept to overcome the brittleness of hard materials. Here, laminated glass composites with a partially segmented micro-architecture are fabricated usin...

The ingenious hierarchical structure of enamel composed of rods and protein produces excellent fracture resistance. However, the fracture resistance mechanism in the inner enamel is unknown. The micromechanical models of enamel are constructed to numerically analyze the mechanical behaviors of the inner enamel with different decussation angles and...

White matter in the brain is structurally anisotropic consisting of large bundle of aligned axonal fibers. Hyperelastic, transversely isotropic constitutive models are typically used in the modeling and simulation of such tissues. However, most studies constrain the material models to describe the mechanical behavior of white matter in the limit of...

Calibration of the stereo vision systems is a crucial step for precise 3D measurements. Restricted by the outdoors’ large field of view (FOV), the conventional method based on precise calibration boards is not suitable since the calibration process is time consuming and the calibration accuracy is not guaranteed. In this paper, we propose a calibra...

Solitary waves in hyperelastic structures propagate stably in absence of external forces. However, as the external forces increase, the stability of solitary waves may lose and then chaotic behaviors may appear. In this paper, solitary waves and chaotic motions of an infinitely long cylinder with an internal heat source are investigated. Moreover,...

Temperature-induced deformation in the infrared detector chip is a key index for evaluating image aberration and stress concentration. Development of an evaluation means for simultaneous characterization of 3D deformation is of great interest to engineering societies. In this study, an integrated device based on speckle interferometry has been deve...

Lock-in thermography (LT) is a non-destructive evaluation method capable of inspecting defects in composites by calculating differences of the thermal amplitude and phase between sound and defective regions. This method greatly reduces influences of non-uniform heating and emissivity in detection, while a single excitation frequency limits the dept...

Phase shifting technique is widely used in determination of photoelastic parameters. Efficient full-field stress quantification remains a challenge due to cumbersome rotation of optical elements in the polarizer and the complex stress separation strategy. By deriving the mathematical expressions with the Stokes parameters with the use of a polariza...

Enamel possesses ingenious hierarchical structure that gives rise to superior fracture resistance. Despite considerable efforts devoted to characterization of fracture behavior of enamel, the role of rod decussation in fracture of enamel is largely unknown. In this study, the features of rod decussation in the inner enamel are experimentally identi...

Illumination conditions are an important factor affecting the accuracy of speckle interferometry. High-intensity illumination could cause the speckle images to be overexposed due to the limited dynamic range of the camera, degrading the fringe quality. This study proposes a high-dynamic phase reconstruction method enabling accurate speckle interfer...

Wind power is a reliable source of clean energy that is extensively used around the world. The blades of wind turbines are subject to a variety of mechanical stresses while they rotate and it is important to monitor their condition and diagnose problems to ensure their safe operation. Prevalent methods to this end are designed to be applied when th...

This work reports a novel kind of hybrid magnetorheological elastomer (HMRE) that possesses multi-functions including excellent shear stiffening and magnetorheological (MR) effects, as well as self-healing and printable abilities. The HMRE materials are prepared by embedding carbonyl iron particles (CIPs) into a blend of silicon rubber (SR) and low...

Stress separation is usually achieved by solving differential equations of equilibrium after parameter determination from isochromatics and isoclinics. The numerical error resulting from the stress determination is a main concern as it is always a function of parameters in discretization. To improve the accuracy of stress calculation, a novel meshl...

Video deflectometers, as a real‐time, contactless optical means, show great potentials in monitoring structural deflections. However, variations of illumination conditions pose a severe challenge on accurate measurement. In this study, a strategy with global illumination adjustment has been proposed to dynamically change the exposure time of the ca...

Image-based displacement measurement techniques are widely used for sensing the deformation of structures, and plays an increasing role in structural health monitoring owing to its benefit of non-contacting. In this study, a non-overlapping dual camera measurement model with the aid of global navigation satellite system (GNSS) is proposed to sense...

Stereo digital image correlation (stereo-DIC) technique shows a powerful capacity on full-field three-dimensional (3D) deformation measurement of rotary machine structures. However, it remains a challenge for underwater applications due to difficulties in imaging, stereo calibration, light refraction, and so on. In this paper, its potential in char...

This work presents an ultrasensitive three-dimensional (3D) structured sensor with out-of-plane tactility and non-contact perception capabilities. It is composed of flexible silver nanowire-patterned magnetic film and the printed heat-responsive polymer skeleton by means of spin-coating, masking, and printing technologies. Besides the capabilities...

Bacground: It is of great significance to optimize the finite element model by spinal flexibility of adolescent idiopathic scoliosis (AIS) patients. The elastic modulus of the intervertebral disc is of critical importance in determining the overall flexibility of the spine. The aim of the present study was to optimize the finite element model of Le...

Thermography and shearography are optical techniques for detecting and characterizing subsurface defects in structures. Both techniques possess unique advantages and abilities, as well as limitations, based on their distinct mechanisms. In this study, the feasibility in fusion of thermography and shearography is explored. Thermal excitation is sele...

Measuring the three-dimensional (3D) deformation of submerged objects through different media with the stereo digital image correlation (stereo-DIC) method involves the refractive optical imaging problem where the non-linear transmission of light is induced by a change of medium density. The problem invalidates the underlying single viewpoint assum...

At small scales, shape-programmable magnetic materials and self-sensing conductive materials have an enticing potential for realizing the functionalities that are unattainable by traditional machines. This work reports a facile preparation method of aself-sensing magnetism-responsive anisotropic films (SMAF) in which magnetic materials and conducti...

The determination of defect depth is one of the important advantages of pulsed thermography. The existing methods for depth estimation in pulsed thermography are generally established based on the one-dimension heat conduction along the thickness of the sample. However, most of the methods neglect the effects of defect size and sample thickness, wh...

Calibration of a stereo vision system is essential for three-dimensional shape and deformation measurements. Although the target-based calibration technique is a good solution, it comes with limitations in a large field of view (FOV) measurement due to the target size and difficulties in operation. In this paper, a method using the inertial measure...

Real-time monitoring of structural health conditions for rotary objects is of importance for safety assessments. In this work, an efficient algorithm based on digital image correlation is presented to achieve accurate rotational matching in real time. The proposed algorithm measures rotation in object motion with an integer pixel search followed by...

Infrared thermography (IRT) is a full-field, contactless technique that has been widely used for nondestructive evaluation of structural materials due to many advantages. One of the major limitations of IRT is the fuzzy edge and low contrast in the inspected images—as well as the cost of the system. An efficient image post-processing with an afford...

Recovering the geometric shape of deformable objects from images is essential to optical three-dimensional (3D) deformation measurements and is also actively pursued by researchers. Most of the existing techniques retrieve the shape data with triangulation based on pre-estimated stereo correspondences. In this paper, we instead propose to recover d...

Owing to the unique non-self-similar hierarchical microstructure, enamel achieves the balance of high stiffness and toughness, and in turn provides important ideas for the bio-inspired materials design. In this study, a multiscale numerical study has been conducted to investigate whether the property of high stiffness and large energy dissipation c...

The ion thruster is an engine with high specific impulse for satellites and spacecrafts, which uses electric energy to boost the spacecraft. The ion optical system, also known as gate assemblies which consist of acceleration and screen grids, is the key component of the ion thruster. In this paper, the static mechanical properties of the C/C compos...

The video deflectometer based on digital image correlation is a non-contacting optical measurement method which has become a useful tool for characterization of the vertical deflections of large structures. In this study, a novel method which considers the variations of pitch angles in full field has been proposed. This method allows deflection mea...

A shearography system has been developed to inspect the external heat proof coating bonded to a cylinder. The system consists of a shearography device integrated with thermal excitation, a mechanical translation and rotation device, and a central control unit. The translation and the rotation are driven with 2 servo motors. The combination of these...

The tensile response, the low cycle fatigue (LCF) resistance, and the creep behavior of an aluminum (Al) cast alloy are studied at ambient and elevated temperatures. A non-contact real-time optical extensometer based on the digital image correlation (DIC) is developed to achieve strain measurements without damage to the specimen. The optical extens...

Objectives: To explore the effect of adhesive failure and defects between the crown and cement on the stress distribution within all-ceramic crowns and the corresponding risk of failure. Methods: An IPS e.max crown of lithium disilicate produced by CAD/CAM for a first mandibular molar was modeled using finite element analysis based on X-ray micr...

Photoelasticity is an effective method for evaluating the stress and its spatial variations within a stressed body. In the present study, a method to determine the stress distribution by means of phase shifting and a modified shear-difference is proposed. First, the orientation of the first principal stress and the retardation between the principal...

An optical system for measuring the coefficient of thermal expansion (CTE) of materials has been developed based on electronic speckle interferometry. In this system, the temperature can be varied from −60°C to 180°C with a Peltier device. A specific specimen geometry and an optical arrangement based on the Michelson interferometer are proposed to...

Objective To investigate the variations of elastic modulus and hardness of human dentin with aging and location. Methods The non-carious third molars were collected and divided into youth group, middle-aged group and elderly group. Nanoidentation test was conducted on the dentin specimens from multiple regions to test their mechanical properties. R...

Thin sheet steel components with a thickness less than 2.5 mm are commonly used in automobile manufacture. Due to the small thickness, the specimens are easy to buckle when subjected to tensile and compressive loads in low-cycle fatigue tests. To improve their stability, the specimens are designed with short gage length. Restrained by the length of...

In this study, a shearography system integrated with a coherent fiber-optic illumination and a fiber-optic imaging bundle is presented to inspect the quality of the interior surface of a cylindrical vessel for safety purposes. The specific optical arrangement is designed for the inspection of a certain area at a small working distance. The optical...

Dentin possesses unique hierarchical structure through long-term natural selection, which imparts exceptional mechanical properties to this hard tissue. In this study, the combined effects of ductile fracture of intertubular dentin (ITD) and brittle cracking of peritubular dentin (PTD) on the crack initiation and propagation in the composite micros...

Due to the superior pigment and high flexural strength, machinable lithium disilicate ceramics can be used as a monolithic crown or veneering porcelains on the zirconia core to form the all-ceramic crowns by sintering or bonding procedures. This paper reports the research on the differences in stress distributions amongst these three types of all-c...

Interfacial behavior in the microstructure and the plastic deformation in the protein matrix influence the overall mechanical properties of biological hard tissues. A cohesive finite element model has been developed to investigate the inelastic mechanical properties of bone-like biocomposites consisting of hard mineral crystals embedded in soft bio...

Digital image correlation (DIC) has been successfully applied for evaluating the mechanical behavior of biological tissues. A three-dimensional (3-D) DIC system has been developed and applied to examining the motion of bones in the human foot. To achieve accurate, real-time displacement measurements, an algorithm including matching between sequenti...

Digital image correlation (DIC) has been widely accepted as a method for displacement and strain measurement and is applied in a variety of engineering fields. Most DIC algorithms encounter errors in measuring the deformation in conditions that involve rotation since they are designed without considering rotation of the deformed object. In this pap...

Objective: ?To study the effect of different degrees of distal tibial varus and valgus deformities on the tibiotalar joint contact, and to understand the role of fibular osteotomy. Methods: ?Eight cadaveric lower legs were used for biomechanical study. Nine conditions were included: normal ankle joint (group A), 10° varus (group B), 5° varus (gr...

The algorithms for Digital image correlation (DIC) in subpixel determination have been well developed regarding the accuracy and efficiency. In this paper, an efficient integer-pixel search scheme with combination of an improved particle swarm optimization (PSO) algorithm and the block-based gradient descent search (BBGDS) algorithm has been propos...

Statement of significance: The mechanical behavior of enamel has been studied for over 3 decades. Due to the limited volume of tissue available for evaluation, past work has been largely based on indentation methods. In this investigation we have evaluated the resistance to fracture of human enamel using a conventional fracture mechanics approach...

The aim of this study is to investigate the change of mechanical properties of human dentin due to aging and spatial variation. Sections of coronal dentin are made from human molars in three groups: young, mid-aged, and old patients. A nanoindentation test is conducted from regions near the pulp to the dentin-enamel junction (DEJ) to evaluate the l...

Inspired by the unique microstructure of dentin, in which the hard peritubular dentin surrounding the dentin tubules is embedded in the soft intertubular dentin, we explore the crack propagation in the bioinspired materials with fracture process zone possessing a dentin-like microstructure, i.e. the composite structure consisting of a soft matrix a...

The quality of bonding is often a concern in rubber-to-metal bonded parts with regard to the integrity and stability of the structure. In this study, shearography has been used to detect the out-of-plane deformation of the defects caused by thermal and vacuum stresses. A sample of the vulcanized styrene-butadiene rubber bonded to steel with known a...

Objective: To analyze the contact failure of monolithic lithium disilicate CAD/CAM crowns by experiment and numerical simulation, and explore the influences of adhesives aging in water on load-bearing capacity of the crowns. Methods: The specimens of sectioned monolithic lithium disilicate crowns were designed and manufactured, and evenly divided i...

Non-contact and accurate motion measurement of the rotary objects is crucial in engineering applications. A modified Newton-Raphson algorithm, which is capable of positioning marks with large rotation, has been proposed. A stereo imaging system with a pair of synchronized digital high-speed cameras was developed and achieved full-field displacement...

Characterizing the strain-life fatigue behavior of thin sheet metals is often challenging since the required specimens have short gauge lengths to avoid buckling, thereby preventing the use of conventional mechanical extensometers. To overcome this obstacle a microscopic optical imaging system has been developed to measure the strain amplitude duri...

Objective: Analysis of mechanical measurements in laparoendoscopic single-site surgery (LESS) is important for instrument design and surgical simulators. The aim of this study was to develop a measuring system for different instruments and manipulations in LESS using a single-incision laparoscopic surgery (SILS) port. Methods: The loads on the SIL...

Tooth fracture is a major concern in the field of restorative dentistry. However, knowledge of the causes for tooth fracture has developed from contributions that are largely based within the field of mechanics. The present manuscript presents a technical review of advances in understanding the fracture of teeth and the fatigue and fracture behavio...

Dentin has a hierarchical structure and is composed of numerous tubules whose diameters and densities vary with the distances to the dentin-enamel junction. The unique structure determines the mechanical performance of dentin. In this study, a multiscale model, which is based on the combination of the virtual multidimensional internal bond (VMIB) t...

The purpose of this study was to investigate how cyclic loading influenced the fracture toughness of hot-press lithium disilicate and zirconia core materials and whether there was an increase in the propensity for crown failure. Two types of all-ceramic crowns including the IPS e.max Press system (n=24) and the Lava zirconia system (n=24), were sel...

To investigate the effectiveness and biomechanical analysis of 3 fixation methods of screw anterior-posterior fixation (SAPF), screw posterior-anterior fixation (SPAF), and buttress plate fixation (BPF) in treatment of posterior Pilon fractures. Fifteen fresh-frozen skeleto-ligamentous lower leg specimens were harvested to establish the models of p...

The measurement of the rotating object is of great significance in engineering applications. In this study, a high-speed dual camera system based on 3D digital image correlation has been developed in order to monitor the rotation status of the wind turbine blades. The system allows sequential images acquired at a rate of 500 frames per second (fps)...

The aim of this study was to compare failure modes and fracture strength of ceramic structures using a combination of experimental and numerical methods. Twelve specimens with flat layer structures were fabricated from two types of ceramic systems (IPS e.max ceram/e.max press-CP and Vita VM9/Lava zirconia-VZ) and subjected to monotonic load to frac...

Objective: To develop an improved DIC (digital image correlation) algorithm suitable for measuring large ROM (range of motion) of the cervical spine, as traditional DIC algorithm is not capable of accurately measuring ROM of the cervical spine due to its large rotation angles. Methods: An algorithm which allowed rotation of the subset window was pr...

The objective of this investigation is to explore the region-dependent damage behavior of enamel, as well as to develop a good understanding of the deformation mechanisms of enamel with numerical modeling. Nanoindentation experiments have been performed to investigate the load-penetration depth responses for outer and inner enamel. Results show tha...

To study the effect of bleaching on the mechanical properties of human dentin. The finite element method (FEM) based the cohesive zone model had been employed to study the fracture resistance of human dentin. There types of dentin were considered, i.e. original dentin, dentin after direct-bleaching and indirect-bleaching. The bleaching treatments h...

Compared with the coarse-grained counterpart, nanocrystalline (NC) metals have higher strength simultaneously with a decrease in ductility, strain localization is a main factor contributed to the early failure of NC metals during plastic deformation. This work deals with the study of shear banding in fully dense electrodeposited NC Ni sheet with sa...

The superior mechanical properties of enamel, such as excellent penetration and crack resistance, are believed to be related to the unique microscopic structure. In this study, the effects of hydroxyapatite (HAP) crystallite orientation on the mechanical behavior of enamel have been investigated through a series of multiscale numerical simulations....

Objective: To investigate effects of aging on the fracture mechanical behavior of human dentin with finite element numerical method. Methods: The finite element model was established according to the typical compact tension specimen in the experiment. The stable crack growth in human dentin was simulated with the cohesive zone model to compare the...

Researches on mechanical properties of biological hard tissues are of great importance to the prevention and treatment for both bone diseases and oral diseases. Meanwhile, biological materials possess superior mechanical properties due to long-term evolution, and studies on the structure and mechanical properties of these materials can provide usef...

The present paper describes an experimental evaluation on the mechanical behavior of fish scales from Cyprinus carpio using a novel experimental approach. Scales were obtained from three different positions about the body (head, mid-length and tail) and as a function of moisture (from hydrated to fully dehydrated). Mechanical properties were determ...

This study aims to obtain the biomechanical properties of porcine cornea so as to provide necessary biomechanical experimental basis for pig-to-human corneal xenotransplantation. Seventeen fresh porcine corneal specimens obtained from pigs aged 4-6 months were examined under inflation conditions to determine the constitutive relationships of the ma...

Objective To analyze the compressive strength and fracture mode between four kinds of dental zirconia CAD/CAM ceramic materials by Hertzian contact test. Methods Four CAD/CAM ceramic materials including Cercon smart, Lava, Porcera, and CEREC 3 were selected. Six zirconia sectioned flat specimens were prepared in each group. The critical load and fr...