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Isogeometric analysis based on geometric reconstruction models

《机械工程前沿（英文）》 2021年 第16卷 第4期   页码 782-797 doi: 10.1007/s11465-021-0648-0

摘要： In isogeometric analysis (IGA), the boundary representation of computer-aided design (CAD) and the tensor-product non-uniform rational B-spline structure make the analysis of three-dimensional (3D) problems with irregular geometries difficult. In this paper, an IGA method for complex models is presented by reconstructing analysis-suitable models. The CAD model is represented by boundary polygons or point cloud and is embedded into a regular background grid, and a model reconstruction method is proposed to obtain the level set function of the approximate model, which can be directly used in IGA. Three 3D examples are used to test the proposed method, and the results demonstrate that the proposed method can deal with complex engineering parts reconstructed by boundary polygons or point clouds.

关键词： isogeometric analysis     reconstruction model     level set function     trimmed element     point cloud    

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Effect of interface adhesion factor on the bearing capacity of strip footing placed on cohesive soil

《结构与土木工程前沿（英文）》 2021年 第15卷 第6期   页码 1494-1503 doi: 10.1007/s11709-021-0768-y

摘要： The problem related to bearing capacity of footing either on pure soil or on pure rock mass has been investigated over the years. Currently, no study deals with the bearing capacity of strip footing on a cohesive soil layer overlying rock mass. Therefore, by implementing the lower bound finite element limit analysis in conjunction with the second-order cone programming and the power cone programming, the ultimate bearing capacity of a strip footing located on a cohesive soil overlying rock mass is determined in this study. By considering the different values of interface adhesion factor (αcr) between the cohesive soil and rock mass, the ultimate bearing capacity of strip footing is expressed in terms of influence factor (If) for different values of cohesive soil layer cover ratio (Tcs/B). The failure of cohesive soil is modeled by using Mohr−Coulomb yield criterion, whereas Generalized Hoek−Brown yield criterion is utilized to model the rock mass at failure. The variations ofIf with different magnitudes of αcr are studied by considering the influence of the rock mass strength parameters of beneath rock mass layer. To examine stress distribution at different depths, failure patterns are also plotted.

关键词： bearing capacity     soil-rock interface     Hoek−Brown yield criterion     plasticity     limit analysis    

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Fractal characteristic evaluation and interpolation reconstruction for surface topography of drilled

《机械工程前沿（英文）》 2021年 第16卷 第4期   页码 840-854 doi: 10.1007/s11465-021-0643-5

摘要： In this paper, an improved fractal interpolation model is proposed to reconstruct the surface topography of composite hole wall. This model adopts the maximum positive deviations and maximum negative deviations between the measured values and trend values to determine the contraction factors. Hole profiles in 24 directions are measured. Fractal parameters are calculated to evaluate the measured surface profiles. The maximum and minimum fractal dimension of the hole wall are 1.36 and 1.07, whereas the maximum and minimum fractal roughness are 4.05 × 10 −5 and 4.36 × 10 −10 m, respectively. Based on the two-dimensional evaluation results, three-dimensional surface topographies in five typical angles (0°, 45°, 90°, 135°, and 165°) are reconstructed using the improved model. Fractal parameter D s and statistical parameters Sa, Sq, and Sz are used to evaluate the reconstructed surfaces. Average error of D s, Sa, Sq, and Sz between the measured surfaces and the reconstructed surfaces are 1.53%, 3.60%, 5.60%, and 9.47%, respectively. Compared with the model in published literature, the proposed model has equal reconstruction effect in relatively smooth surface and is more advanced in relatively rough surface. Comparative results prove that the proposed model for calculating contraction factors is more reasonable.

关键词： surface topography     fractal evaluation     fractal interpolation     reconstruction     composite    

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Experimental verification of the interface wave method to detect interlaminar damage of a metal multilayer

Bing LI,Xu GENG,Tong LU,Lei QIANG,Minghang LI

《机械工程前沿（英文）》 2015年 第10卷 第4期   页码 380-391 doi: 10.1007/s11465-015-0365-7

摘要：

The interface wave traveling along the boundary of two materials has been studied for nearly a century. However, experiments, engineering applications, and interface wave applications to the non-destructive inspection of interlaminar composite have developed slowly. In this research, an experiment that applies Stoneley waves (a type of interfacial wave between two solid half-spaces) is implemented to detect the damage in a multilayer structure. The feasibility of this method is also verified. First, the wave velocity and wave structure of Stoneley waves at a perfectly bonded aluminum-steel interface are obtained by solving the Stoneley wave dispersion equation of two elastic half-spaces. Thereafter, an experiment is conducted to measure the Stoneley wave velocity of an aluminum-steel laminated beam and to locate interlaminar cracks by referring to the Stoneley wave velocity and echo wave time. Results indicate that the location error is less than 2%. Therefore, Stoneley waves show great potential as a non-destructive inspection method of a multilayer structure.

关键词： crack localization     interface waves     Stoneley waves     interlaminar damage     multilayer structure    

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Full-field dynamic strain reconstruction of an aero-engine blade from limited displacement responses

《机械工程前沿（英文）》 2023年 第18卷 第1期 doi: 10.1007/s11465-022-0731-1

摘要： Blade strain distribution and its change with time are crucial for reliability analysis and residual life evaluation in blade vibration tests. Traditional strain measurements are achieved by strain gauges (SGs) in a contact manner at discrete positions on the blades. This study proposes a method of full-field and real-time strain reconstruction of an aero-engine blade based on limited displacement responses. Limited optical measured displacement responses are utilized to reconstruct the full-field strain. The full-field strain distribution is in-time visualized. A displacement-to-strain transformation matrix is derived on the basis of the blade mode shapes in the modal coordinate. The proposed method is validated on an aero-engine blade in numerical and experimental cases. Three discrete vibrational displacement responses measured by laser triangulation sensors are used to reconstruct the full-field strain over the whole operating time. The reconstructed strain responses are compared with the results measured by SGs and numerical simulation. The high consistency between the reconstructed and measured results demonstrates the accurate strain reconstructed by the method. This paper provides a low-cost, real-time, and visualized measurement of blade full-field dynamic strain using displacement response, where the traditional SGs would fail.

关键词： aero-engine blade     displacement response     dynamic strain reconstruction     mode shape     strain gauge    

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Multi-objective optimization of surface texture for the slipperswash plate interface in EHA pumps

《机械工程前沿（英文）》 2022年 第17卷 第4期 doi: 10.1007/s11465-022-0704-4

摘要： Well-designed surface textures can improve the tribological properties and the efficiency of the electro-hydrostatic actuator (EHA) pump under high-speed and high-pressure conditions. This study proposes a multi-objective optimization model to obtain the arbitrarily surface textures design of the slipper/swash plate interface for improving the mechanical and volumetric efficiency of the EHA pump. The model is composed of the lubrication film model, the component dynamic model considering the spinning motion, and the multi-objective optimization model. In this way, the arbitrary-shaped surface texture with the best comprehensive effect in the EHA pump is achieved and its positive effects in the EHA pump prototype are verified. Experimental results show a reduction in wear and an improvement in mechanical and volumetric efficiency by 1.4% and 0.8%, respectively, with the textured swash plate compared with the untextured one.

关键词： electro-hydrostatic actuator     axial piston pump     slipper/swash plate interface     multi-objective optimization     surface texture    

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Thermal analysis of lubricated three-dimensional contact bodies considering interface roughness

《机械工程前沿（英文）》 2022年 第17卷 第2期 doi: 10.1007/s11465-022-0672-8

摘要： Surface roughness and thermal action are of remarkable importance in the lubrication performance of mechanical components, especially in extreme conditions. However, available studies mainly focus on the full-film lubrication conditions without considering temperature rise and real 3D surface roughness due to the complexity of surface topography and temperature characteristics. Moreover, studies on the interfacial thermal behaviors of 3D rough surface lubricated contact in an extended range of working conditions remain limited. In this paper, a deterministic mixed thermal elastohydrodynamic lubrication model considering real 3D surface roughness and thermal effects is proposed. In this model, pressure and temperature are coupled with each other, the computation of elastic deformation is accelerated through the discrete convolution and fast Fourier transform method, the temperature field is calculated with the column sweeping technique, and the semi-system method is introduced to improve convergence and numerical stability under severe conditions. The model is validated by comparing its results with available published numerical and experimental results. The thermal behaviors of the contact interface are studied in a wide range of working conditions. The influences of surface roughness and thermal effect on lubrication performance are revealed. The results show that the proposed model can be used as a powerful analysis tool for lubrication performance and temperature prediction in various heavy-load, high-speed lubricated components over a wide range of lubrication conditions.

关键词： thermal elastohydrodynamic lubrication     surface roughness effect     thermal effect     temperature characteristics     severe conditions    

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Shape reconstruction of parallelogram flaw

ZHENG Gangfeng, WU Bin, HE Cunfu

《机械工程前沿（英文）》 2008年 第3卷 第1期   页码 17-22 doi: 10.1007/s11465-008-0015-4

摘要： To reconstruct the shape of the scatterer in elastic media, the authors deduce the Born approximation solution of the two-dimensional scattering problem, which includes the shape factor that embodies all information about the shape of the scatterer. Accordingly, the change in the shape of the scatterer only necessitates the number of the corresponding new shape factors. For a parallelogram void in a long Al rod, its shape factor can be obtained. In view of the definition of a characteristic function, the shape factor has a corresponding integral representation. Obviously, the shape factor can be considered as a Fourier transform of the characteristic function, which is reconstructed from the inverse Fourier transform. The integral equation is considered as the basic equation to reconstruct the shape of the scatterer. The identification of the geometrical character of a flaw is then given by the two dimensional inverse Born approximation in a low-frequency range. For the parallelogram void, a theoretical calculating identification is performed. At the same time, the numerical results are obtained by the finite element method.

关键词： approximation     scatterer     scattering problem     information     inverse    

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The ecological system and the regionalization of landscape reconstruction in northwest of China

Peicheng LI,Guoyuan DU,Qilei LI,Jinfeng WANG,Feimin ZHENG

《农业科学与工程前沿（英文）》 2014年 第1卷 第4期   页码 291-298 doi: 10.15302/J-FASE-2014033

摘要： The northwest of China is a vast area with abundant resources and significant potential for development. However, the ecological system is extremely vulnerable to damage and must be managed carefully. Thus, the Chinese government is strengthening research on improvement and reconstruction of the ecological system and landscape in northwest of China while moving forward with large-scale development in west China. The disadvantages and vulnerabilities in the northwest area in China are presented. It is suggested that the reconstruction of landscape should be conducted by step by step regionalization across the various ecological systems in the 3.04 million km northwest area of China. The first level regionalization results of reconstruction of landscape are discussed.

关键词： reconstruction of landscape     ecological system     the northwest area of China     science and technology action    

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Extrapolation reconstruction of wind pressure fields on the claddings of high-rise buildings

Yehua SUN, Guquan SONG, Hui LV

《结构与土木工程前沿（英文）》 2019年 第13卷 第3期   页码 653-666 doi: 10.1007/s11709-018-0503-5

摘要： Recent research about reconstruction methods mainly used the interpolation reconstruction of the fluctuating wind pressure field on the surface. However, to investigate wind pressure at the edge of the building, the work presented in this paper focuses on the extrapolation reconstruction of wind pressure fields. Here, we propose an improved proper orthogonal decomposition (POD) and Kriging method with a von Kármán correlation function to resolve this issue. The studies show that it works well for not only interpolation reconstruction but also extrapolation reconstruction. The proposed method does require determination of the Hurst exponent and other parameters analysed from the original data. Hence, the fluctuating wind fields have been characterized by the von Kármán correlation function, as an a priori function. Compared with the cubic spline method and different variogram, preliminary results suggest less time consumption and high efficiency in extrapolation reconstruction at the edge.

关键词： extrapolation reconstruction     proper orthogonal decomposition     Kriging method     von Kármán function     Hurst exponent     rescaled range analysis    

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Tribological mechanism of carbon group nanofluids on grinding interface under minimum quantity lubrication

《机械工程前沿（英文）》 2023年 第18卷 第1期 doi: 10.1007/s11465-022-0733-z

摘要： Carbon group nanofluids can further improve the friction-reducing and anti-wear properties of minimum quantity lubrication (MQL). However, the formation mechanism of lubrication films generated by carbon group nanofluids on MQL grinding interfaces is not fully revealed due to lack of sufficient evidence. Here, molecular dynamic simulations for the abrasive grain/workpiece interface were conducted under nanofluid MQL, MQL, and dry grinding conditions. Three kinds of carbon group nanoparticles, i.e., nanodiamond (ND), carbon nanotube (CNT), and graphene nanosheet (GN), were taken as representative specimens. The [BMIM]BF4 ionic liquid was used as base fluid. The materials used as workpiece and abrasive grain were the single-crystal Ni–Fe–Cr series of Ni-based alloy and single-crystal cubic boron nitride (CBN), respectively. Tangential grinding force was used to evaluate the lubrication performance under the grinding conditions. The abrasive grain/workpiece contact states under the different grinding conditions were compared to reveal the formation mechanism of the lubrication film. Investigations showed the formation of a boundary lubrication film on the abrasive grain/workpiece interface under the MQL condition, with the ionic liquid molecules absorbing in the groove-like fractures on the grain wear’s flat face. The boundary lubrication film underwent a friction-reducing effect by reducing the abrasive grain/workpiece contact area. Under the nanofluid MQL condition, the carbon group nanoparticles further enhanced the tribological performance of the MQL technique that had benefited from their corresponding tribological behaviors on the abrasive grain/workpiece interface. The behaviors involved the rolling effect of ND, the rolling and sliding effects of CNT, and the interlayer shear effect of GN. Compared with the findings under the MQL condition, the tangential grinding forces could be further reduced by 8.5%, 12.0%, and 14.1% under the diamond, CNT, and graphene nanofluid MQL conditions, respectively.

关键词： grinding     minimum quantity lubrication     carbon group nanofluid     tribological mechanism    

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A dynamic stiffness-based framework for harmonic input estimation and response reconstruction considering

Yixian LI; Limin SUN; Wang ZHU; Wei ZHANG

《结构与土木工程前沿（英文）》 2022年 第16卷 第4期   页码 448-460 doi: 10.1007/s11709-022-0805-5

摘要： In structural health monitoring (SHM), the measurement is point-wise but structures are continuous. Thus, input estimation has become a hot research subject with which the full-field structural response can be calculated with a finite element model (FEM). This paper proposes a framework based on the dynamic stiffness theory, to estimate harmonic input, reconstruct responses, and to localize damages from seriously deficient measurements. To begin, Fourier transform converts the dynamic equilibrium equation to an equivalent static one in the frequency domain, which is under-determined since the dimension of measurement vector is far less than the FEM-node number. The principal component analysis has been adopted to “compress” the under-determined equation, and formed an over-determined equation to estimate the unknown input. Then, inverse Fourier transform converts the estimated input in the frequency domain to the time domain. Applying this to the FEM can reconstruct the target responses. If a structure is damaged, the estimated nodal force can localize the damage. To improve the damage-detection accuracy, a multi-measurement-based indicator has been proposed. Numerical simulations have validated that the proposed framework can capably estimate input and reconstruct multi-types of full-field responses, and the damage indicator can localize minor damages even with the existence of noise.

关键词： dynamic stiffness     principal component analysis     response reconstruction     damage localization     under-determined equation    

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Development of surface reconstruction algorithms for optical interferometric measurement

Dongxu WU, Fengzhou FANG

《机械工程前沿（英文）》 2021年 第16卷 第1期   页码 1-31 doi: 10.1007/s11465-020-0602-6

摘要： Optical interferometry is a powerful tool for measuring and characterizing areal surface topography in precision manufacturing. A variety of instruments based on optical interferometry have been developed to meet the measurement needs in various applications, but the existing techniques are simply not enough to meet the ever-increasing requirements in terms of accuracy, speed, robustness, and dynamic range, especially in on-line or on-machine conditions. This paper provides an in-depth perspective of surface topography reconstruction for optical interferometric measurements. Principles, configurations, and applications of typical optical interferometers with different capabilities and limitations are presented. Theoretical background and recent advances of fringe analysis algorithms, including coherence peak sensing and phase-shifting algorithm, are summarized. The new developments in measurement accuracy and repeatability, noise resistance, self-calibration ability, and computational efficiency are discussed. This paper also presents the new challenges that optical interferometry techniques are facing in surface topography measurement. To address these challenges, advanced techniques in image stitching, on-machine measurement, intelligent sampling, parallel computing, and deep learning are explored to improve the functional performance of optical interferometry in future manufacturing metrology.

关键词： surface topography     measurement     optical interferometry     coherence envelope     phase-shifting algorithm    

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Performance of soft-hard-soft (SHS) cement based composite subjected to blast loading with consideration of interface

Jun WU,Xuemei LIU

《结构与土木工程前沿（英文）》 2015年 第9卷 第3期   页码 323-340 doi: 10.1007/s11709-015-0301-2

摘要： This paper presents a combined experimental and numerical study on the damage and performance of a soft-hard-soft (SHS) multi-layer cement based composite subjected to blast loading which can be used for protective structures and infrastructures to resist extreme loadings, and the composite consists of three layers of construction materials including asphalt concrete (AC) on the top, high strength concrete (HSC) in the middle, and engineered cementitious composites (ECC) at the bottom. To better characterize the material properties under dynamic loading, interface properties of the composite were investigated through direct shear test and also used to validate the interface model. Strain rate effects of the asphalt concrete were also studied and both compressive and tensile dynamic increase factor (DIF) curves were improved based on split Hopkinson pressure bar (SHPB) test. A full-scale field blast test investigated the blast behavior of the composite materials. The numerical model was established by taking into account the strain rate effect of all concrete materials. Furthermore, the interface properties were also considered into the model. The numerical simulation using nonlinear finite element software LS-DYNA agrees closely with the experimental data. Both the numerical and field blast test indicated that the SHS composite exhibited high resistance against blast loading.

关键词： high strength concrete (SHS)     engineered cementitious composite     interface     blast test     strain rate effect    

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Recent advances in “universal” influenza virus antibodies: the rise of a hidden trimeric interface in

Yulu Wang, Dan Hu, Yanling Wu, Tianlei Ying

《医学前沿（英文）》 2020年 第14卷 第2期   页码 149-159 doi: 10.1007/s11684-020-0764-y

摘要： Influenza causes seasonal outbreaks yearly and unpredictable pandemics with high morbidity and mortality rates. Despite significant efforts to address influenza, it remains a major threat to human public health. This issue is partially due to the lack of antiviral drugs with potent antiviral activity and broad reactivity against all influenza virus strains and the rapid emergence of drug-resistant variants. Moreover, designing a universal influenza vaccine that is sufficiently immunogenic to induce universal antibodies is difficult. Some novel epitopes hidden in the hemagglutinin (HA) trimeric interface have been discovered recently, and a number of antibodies targeting these epitopes have been found to be capable of neutralizing a broad range of influenza isolates. These findings may have important implications for the development of universal influenza vaccines and antiviral drugs. In this review, we focused on the antibodies targeting these newly discovered epitopes in the HA domain of the influenza virus to promote the development of universal anti-influenza antibodies or vaccines and extend the discovery to other viruses with similar conformational changes in envelope proteins.

关键词： influenza virus     neutralizing antibody     hemagglutinin     globular head region     trimeric interface    

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标题 作者 时间 类型 操作

Isogeometric analysis based on geometric reconstruction models

期刊论文

Effect of interface adhesion factor on the bearing capacity of strip footing placed on cohesive soil

期刊论文

Fractal characteristic evaluation and interpolation reconstruction for surface topography of drilled

期刊论文

Experimental verification of the interface wave method to detect interlaminar damage of a metal multilayer

Bing LI,Xu GENG,Tong LU,Lei QIANG,Minghang LI

期刊论文

Full-field dynamic strain reconstruction of an aero-engine blade from limited displacement responses

期刊论文

Multi-objective optimization of surface texture for the slipperswash plate interface in EHA pumps

期刊论文

Thermal analysis of lubricated three-dimensional contact bodies considering interface roughness

期刊论文

Shape reconstruction of parallelogram flaw

ZHENG Gangfeng, WU Bin, HE Cunfu

期刊论文

The ecological system and the regionalization of landscape reconstruction in northwest of China

Peicheng LI,Guoyuan DU,Qilei LI,Jinfeng WANG,Feimin ZHENG

期刊论文

Extrapolation reconstruction of wind pressure fields on the claddings of high-rise buildings

Yehua SUN, Guquan SONG, Hui LV

期刊论文

Tribological mechanism of carbon group nanofluids on grinding interface under minimum quantity lubrication

期刊论文

A dynamic stiffness-based framework for harmonic input estimation and response reconstruction considering

Yixian LI; Limin SUN; Wang ZHU; Wei ZHANG

期刊论文

Development of surface reconstruction algorithms for optical interferometric measurement

Dongxu WU, Fengzhou FANG

期刊论文

Performance of soft-hard-soft (SHS) cement based composite subjected to blast loading with consideration of interface

Jun WU,Xuemei LIU

期刊论文

Recent advances in “universal” influenza virus antibodies: the rise of a hidden trimeric interface in

Yulu Wang, Dan Hu, Yanling Wu, Tianlei Ying

期刊论文