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Refined analysis of axi-symmetric circular cylinder in the axial magnetic field without ad hoc assumption

Baosheng ZHAO, Yang GAO, Yingtao ZHAO, Dechen ZHANG

《机械工程前沿（英文）》 2011年 第6卷 第3期   页码 318-323 doi: 10.1007/s11465-011-0232-0

摘要：

The refined theory for axi-symmetric magnetoelastic circular cylinder is deduced systematically and directly from linear magnetoelasticity theory. Based on the general solution of magnetoelastic equation and the Lur’e method, the refined theory yields the solutions for magnetoelastic circular cylinder without ad hoc assumptions. On the basis of the refined theory developed in the present study, solutions are obtained for magnetoelastic circular cylinder with homogeneous and non-homogenous boundary conditions, respectively. For the circular cylinder with homogeneous boundary conditions, the refined theory provides exact solutions that satisfy all of the governing equations. The exact solutions can be divided into three parts: the 2-orders equation, the transcendental equation, and the magnetic equation. In the case of non-homogenous boundary conditions, the approximate governing equations are accurate up to the high-order terms with respect to cylinder radius.

关键词： refined analysis     axially symmetric deformation     circular cylinder     Bessel’s function     axial magnetic field    

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A total torque index for dynamic performance evaluation of a radial symmetric six-legged robot

Kejia LI, Xilun DING, Marco CECCARELL

《机械工程前沿（英文）》 2012年 第7卷 第2期   页码 219-230 doi: 10.1007/s11465-012-0320-9

摘要：

This article focuses on the dynamic index and performance of a radial symmetric six-legged robot. At first the structure of the robot is described in brief and its inverse kinematics is presented. Then the dynamic model is formulated as based on the Lagrange equations. A novel index of total torque is proposed by considering the posture of the supporting legs. The new index can be used to optimize the leg’s structure and operation for consuming minimum power and avoiding unstable postures of the robot. A characterization of the proposed six-legged robot is obtained by a parametric analysis of robot performance through simulation using the presented dynamic model. Main influences are outlined as well as the usefulness of the proposed performance index.

关键词： six-legged robots     dynamic modeling     performance index    

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Shear stress distribution prediction in symmetric compound channels using data mining and machine learning

Zohreh SHEIKH KHOZANI, Khabat KHOSRAVI, Mohammadamin TORABI, Amir MOSAVI, Bahram REZAEI, Timon RABCZUK

《结构与土木工程前沿（英文）》 2020年 第14卷 第5期   页码 1097-1109 doi: 10.1007/s11709-020-0634-3

摘要： Shear stress distribution prediction in open channels is of utmost importance in hydraulic structural engineering as it directly affects the design of stable channels. In this study, at first, a series of experimental tests were conducted to assess the shear stress distribution in prismatic compound channels. The shear stress values around the whole wetted perimeter were measured in the compound channel with different floodplain widths also in different flow depths in subcritical and supercritical conditions. A set of, data mining and machine learning algorithms including Random Forest (RF), M5P, Random Committee, KStar and Additive Regression implemented on attained data to predict the shear stress distribution in the compound channel. Results indicated among these five models; RF method indicated the most precise results with the highest value of 0.9. Finally, the most powerful data mining method which studied in this research compared with two well-known analytical models of Shiono and Knight method (SKM) and Shannon method to acquire the proposed model functioning in predicting the shear stress distribution. The results showed that the RF model has the best prediction performance compared to SKM and Shannon models.

关键词： compound channel     machine learning     SKM model     shear stress distribution     data mining models    

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Hierarchical porous carbon derived from one-step self-activation of zinc gluconate for symmetric supercapacitors

《化学科学与工程前沿（英文）》 2023年 第17卷 第4期   页码 387-394 doi: 10.1007/s11705-022-2250-3

摘要： Porous carbons with high specific area surfaces are promising electrode materials for supercapacitors. However, their production usually involves complex, time-consuming, and corrosive processes. Hence, a straightforward and effective strategy is presented for producing highly porous carbons via a self-activation procedure utilizing zinc gluconate as the precursor. The volatile nature of zinc at high temperatures gives the carbons a large specific surface area and an abundance of mesopores, which avoids the use of additional activators and templates. Consequently, the obtained porous carbon electrode delivers a satisfactory specific capacitance and outstanding cycling durability of 90.9% after 50000 cycles at 10 A∙g–1. The symmetric supercapacitors assembled by the optimal electrodes exhibit an acceptable rate capability and a distinguished cycling stability in both aqueous and ionic liquid electrolytes. Accordingly, capacitance retention rates of 77.8% and 85.7% are achieved after 50000 cycles in aqueous alkaline electrolyte and 10000 cycles in ionic liquid electrolyte. Moreover, the symmetric supercapacitors deliver high energy/power densities of 49.8 W∙h∙kg–1/2477.8 W∙kg–1 in the Et4NBF4 electrolyte, outperforming the majority of previously reported porous carbon-based symmetric supercapacitors in ionic liquid electrolytes.

关键词： self-activation     zinc organic salts     abundant mesopores     symmetric supercapacitor     liquid electrolyte    

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Isogeometric topology optimization based on energy penalization for symmetric structure

Xianda XIE, Shuting WANG, Ming YE, Zhaohui XIA, Wei ZHAO, Ning JIANG, Manman XU

《机械工程前沿（英文）》 2020年 第15卷 第1期   页码 100-122 doi: 10.1007/s11465-019-0568-4

摘要： We present an energy penalization method for isogeometric topology optimization using moving morphable components (ITO–MMC), propose an ITO–MMC with an additional bilateral or periodic symmetric constraint for symmetric structures, and then extend the proposed energy penalization method to an ITO–MMC with a symmetric constraint. The energy penalization method can solve the problems of numerical instability and convergence for the ITO–MMC and the ITO–MMC subjected to the structural symmetric constraint with asymmetric loads. Topology optimization problems of asymmetric, bilateral symmetric, and periodic symmetric structures are discussed to validate the effectiveness of the proposed energy penalization approach. Compared with the conventional ITO–MMC, the energy penalization method for the ITO–MMC can improve the convergence rate from 18.6% to 44.5% for the optimization of the asymmetric structure. For the ITO–MMC under a bilateral symmetric constraint, the proposed method can reduce the objective value by 5.6% and obtain a final optimized topology that has a clear boundary with decreased iterations. For the ITO–MMC under a periodic symmetric constraint, the proposed energy penalization method can dramatically reduce the number of iterations and obtain a speedup of more than 2.

关键词： topology optimization     moving morphable component     isogeometric analysis     energy penalization method     symmetric constraint    

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Effect of steady shear on multi-axial texture of symmetric diblock copolymers

XU Hui, LIU Honglai, HU Ying

《化学科学与工程前沿（英文）》 2007年 第1卷 第1期   页码 26-34 doi: 10.1007/s11705-007-0006-8

摘要： The effect of steady shear on multi-axial texture of symmetric diblock copolymer was investigated by using dynamic density functional theory. Through modifying the periodic boundary condition, the parallel-transverse biaxial texture and perpendicular-parallel-transverse triaxial texture have been observed. In the formation of the multi-axial texture, there are two critical velocities μ and µ, at which the transition between the perpendicular and the parallel lamellar morphology, and the transition between the parallel and the transverse lamellar morphology occur, respectively. The two critical velocities increase as the interaction parameter increases, but they almost remain constant at different shear rates. Furthermore, the rotation from the transverse lamellae to the parallel lamellae induced by the shear strain, and the increase of lamellar spacings of the three lamellae after removing the shear, have also been observed by the time evolution of the morphologies. These phenomena are consistent with experimental work.
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Resistance of large deformation of the Wushaoling Tunnel F7 soft fault

ZHAO Xufeng, CHEN Haiming, WANG Chunmiao

《结构与土木工程前沿（英文）》 2007年 第1卷 第1期   页码 123-127 doi: 10.1007/s11709-007-0013-3

摘要： In this article, the mechanical characteristics of the squeeze of the F7 fault of the Wushaoling Tunnel are analyzed. The measurements and techniques are proposed to resist the deformation. The result indicates that the method of construction to control the further squeeze deflection is appropriate.

关键词： F7     deformation     appropriate     construction     mechanical    

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Numerical modeling of nonlinear deformation of polymer composites based on hyperelastic constitutive

Qingsheng YANG, Fang XU

《机械工程前沿（英文）》 2009年 第4卷 第3期   页码 284-288 doi: 10.1007/s11465-009-0067-0

摘要： Fiber reinforced polymer (FRP) composites exhibit nonlinear and hyperelastic characteristics under finite deformation. This paper investigates the macroscopic hyperelastic behavior of fiber reinforced polymer composites using a micromechanical model and finite deformation theory based on the hyperelastic constitutive law. The local stress and deformation of a representative volume element are calculated by the nonlinear finite element method. Then, an averaging procedure is used to find the homogenized stress and strain, and the macroscopic stress-strain curves are obtained. Numerical examples are given to demonstrate hyperelastic behavior and deformation of the composites, and the effects of the distribution pattern of fibers are also investigated to model the mechanical behavior of FRP composites.

关键词： composites     hyperelastic     finite deformation     homogenization     micromechanics    

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A continuous/discontinuous deformation analysis (CDDA) method based on deformable blocks for fracture

Yongchang CAI, Hehua ZHU, Xiaoying ZHUANG

《结构与土木工程前沿（英文）》 2013年 第7卷 第4期   页码 369-378 doi: 10.1007/s11709-013-0222-x

摘要： In the framework of finite element meshes, a novel continuous/discontinuous deformation analysis (CDDA) method is proposed in this paper for modeling of crack problems. In the present CDDA, simple polynomial interpolations are defined at the deformable block elements, and a link element is employed to connect the adjacent block elements. The CDDA is particularly suitable for modeling the fracture propagation because the switch from continuous deformation analysis to discontinuous deformation analysis is natural and convenient without additional procedures. The SIFs (stress intensity factors) for various types of cracks, such as kinked cracks or curved cracks, can be easily computed in the CDDA by using the virtual crack extension technique (VCET). Both the formulation and implementation of the VCET in CDDA are simple and straightforward. Numerical examples indicate that the present CDDA can obtain high accuracy in SIF results with simple polynomial interpolations and insensitive to mesh sizes, and can automatically simulate the crack propagation without degrading accuracy.

关键词： fracture     crack     propagation     deformable block     continuous/discontinuous deformation analysis (CDDA)    

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Calculation methods of the crack width and deformation for concrete beams with high-strength steel bars

Jianmin ZHOU, Shuo CHEN, Yang CHEN

《结构与土木工程前沿（英文）》 2013年 第7卷 第3期   页码 316-324 doi: 10.1007/s11709-013-0211-0

摘要： Three groups of concrete beams reinforced with high-strength steel bars were tested, and the crack width and deformation of the specimens were observed and studied. To facilitate the predictions, two simplified formulations according to a theory developed by the first author were proposed. The advantages of the formulations were verified by the test data and compared with several formulas in different codes.

关键词： concrete beam     high-strength steel bar     crack width     deformation    

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Calculation method of radial stress and deformation on conic threaded connections with interference fit

Shoujun CHEN, Qiang LI, Qi AN,

《机械工程前沿（英文）》 2010年 第5卷 第3期   页码 302-307 doi: 10.1007/s11465-010-0018-9

摘要： This paper presents a calculation method for radial stress distribution and deformation on conic threaded connections with interference fit. Based on elastic mechanics, a new calculation model is established using the thick-walled-cylindrical theory. A sample calculation for API 88.9 mm conic threaded connection indicates that the method proposed in this paper is reasonable, and the finite element analysis (FEA) method is used to validate the proposed method. The results obtained by the proposed method and FEA method are identical. The model offers a new way of calculating the radial stress and deformation on conic thread connections with interference fit.

关键词： conic threaded connections     interference fit     radial stress     deformation     finite element analysis (FEA)    

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Simulation of blast induced crater in jointed rock mass by discontinuous deformation analysis method

Youjun NING, Xinmei AN, Jun YANG, Guowei MA,

《结构与土木工程前沿（英文）》 2010年 第4卷 第2期   页码 223-232 doi: 10.1007/s11709-010-0022-5

摘要： Rock blasting is a dynamic process accompanied with the propagations of shock waves and the dispersion of the explosion gas. This paper adopts the discontinuous deformation analysis (DDA) method to simulate the rock blasting process. A dynamic parameter adjustment and the non-reflecting boundary condition are implemented in the DDA method. The sub-block DDA method to simulate fracture problems is used. The blasting process in jointed rock mass is simulated by application of the explosion gas pressure on the expanding borehole walls and induced connected fracture surfaces around the boreholes. The blast craters with different overburdens are derived. The whole process including the explosion gas dispersion, borehole expansion, rock mass failure and cast, and the formation of the final blasting piles in rock blasting are well reproduced numerically. Parametric study for different overburdens is carried out, and the results are analyzed and discussed.

关键词： blast crater     jointed rock mass     explosion gas pressure     discontinuous deformation analysis (DDA) method    

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Rotation errors in numerical manifold method and a correction based on large deformation theory

Ning ZHANG, Xu LI, Qinghui JIANG, Xingchao LIN

《结构与土木工程前沿（英文）》 2019年 第13卷 第5期   页码 1036-1053 doi: 10.1007/s11709-019-0535-5

摘要： Numerical manifold method (NMM) is an effective method for simulating block system, however, significant errors are found in its simulation of rotation problems. Three kinds of errors, as volume expansion, stress vibration, and attenuation of angular velocity, were observed in the original NMM. The first two kind errors are owing to the small deformation assumption and the last one is due to the numerical damping. A large deformation NMM is proposed based on large deformation theory. In this method, the governing equation is derived using Green strain, the large deformation iteration and the open-close iteration are combined, and an updating strategy is proposed. The proposed method is used to analyze block rotation, beam bending, and rock falling problems and the results prove that all three kinds of errors are eliminated in this method.

关键词： numerical manifold method     rotation     large deformation     Green strain     open-close iteration    

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Deformation control criterion of shield tunnel under lateral relaxation of soft soil

《结构与土木工程前沿（英文）》 2023年 第17卷 第5期   页码 780-795 doi: 10.1007/s11709-023-0944-3

摘要： Metro shield tunnels under the lateral relaxation of soil (LRS) are susceptible to significant lateral deformations, which jeopardizes the structural safety and waterproofing. However, deformation control standards for such situations have not been clearly defined. Therefore, based on a specific case, a model test is conducted to realize the LRS of a shield tunnel in a sandy stratum to reveal its effect on segment liners. Subsequently, a deformation control criterion is established. The LRS is simulated by linearly reducing the loads applied to the lateral sides of the segment structure. During lateral unloading, the lateral earth pressure coefficient on the segment decreases almost exponentially, and the structural deformation is characterized by horizontal expansion at the arch haunches and vertical shrinkage at the arch vault and arch bottom. Based on the mechanical pattern of the segment structure and the acoustic emission, the deformation response of a segment can be classified into three stages: elastic and quasi-elastic, damage, and rapid deformation development. For a shield tunnel with a diameter of approximately 6 m and under the lateral relaxation of sandy soil, when the ellipticity of the segment is less than 2.71%, reinforcement measures are not required. However, the segment deformation must be controlled when the ellipticity is 2.71% to 3.12%; in this regard, an ellipticity of 3% can be used as a benchmark in similar engineering projects.

关键词： shield tunnel     lateral relaxation of soil     deformation control criterion of segment structure     model test    

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Deformation field and crack analyses of concrete using digital image correlation method

Yijie HUANG, Xujia HE, Qing WANG, Jianzhuang XIAO

《结构与土木工程前沿（英文）》 2019年 第13卷 第5期   页码 1183-1199 doi: 10.1007/s11709-019-0545-3

摘要： The study on the deformation distribution and crack propagation of concrete under axial compression was conducted by the digital image correlation (DIC) method. The main parameter in this test is the water-cement ( / ) ratio. The novel analysis process and numerical program for DIC method were established. The displacements and strains of coarse aggregate, and cement mortar and interface transition zone (ITZ) were obtained and verified by experimental results. It was found that the axial displacement distributed non-uniformly during the loading stage, and the axial displacements of ITZs and cement mortar were larger than that of coarse aggregates before the occurrence of macro-cracks. The effect of / on the horizontal displacement was not obvious. Test results also showed that the transverse and shear deformation concentration areas (DCAs) were formed when stress reached 30%–40% of the peak stress. The transverse and shear DCAs crossed the cement mortar, and ITZs and coarse aggregates. However, the axial DCA mainly surrounded the coarse aggregate. Generally, the higher / was, the more size and number of DCAs were. The crack propagations of specimens varied with the variation of / . The micro-crack of concrete mainly initiated in the ITZs, irrespective of the / . The number and distribution range of cracks in concrete with high / were larger than those of cracks in specimen adopting low / . However, the value and width of cracks in high / specimen were relatively small. The / had an obvious effect on the characteristics of concrete deterioration. Finally, the characteristics of crack was also evaluated by comparing the calculated results.

关键词： deformation filed distribution     crack development     digital image correlation method     mechanical properties     water-cement ratio     characteristics of deformation and crack    

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标题 作者 时间 类型 操作

Refined analysis of axi-symmetric circular cylinder in the axial magnetic field without ad hoc assumption

Baosheng ZHAO, Yang GAO, Yingtao ZHAO, Dechen ZHANG

期刊论文

A total torque index for dynamic performance evaluation of a radial symmetric six-legged robot

Kejia LI, Xilun DING, Marco CECCARELL

期刊论文

Shear stress distribution prediction in symmetric compound channels using data mining and machine learning

Zohreh SHEIKH KHOZANI, Khabat KHOSRAVI, Mohammadamin TORABI, Amir MOSAVI, Bahram REZAEI, Timon RABCZUK

期刊论文

Hierarchical porous carbon derived from one-step self-activation of zinc gluconate for symmetric supercapacitors

期刊论文

Isogeometric topology optimization based on energy penalization for symmetric structure

Xianda XIE, Shuting WANG, Ming YE, Zhaohui XIA, Wei ZHAO, Ning JIANG, Manman XU

期刊论文

Effect of steady shear on multi-axial texture of symmetric diblock copolymers

XU Hui, LIU Honglai, HU Ying

期刊论文

Resistance of large deformation of the Wushaoling Tunnel F7 soft fault

ZHAO Xufeng, CHEN Haiming, WANG Chunmiao

期刊论文

Numerical modeling of nonlinear deformation of polymer composites based on hyperelastic constitutive

Qingsheng YANG, Fang XU

期刊论文

A continuous/discontinuous deformation analysis (CDDA) method based on deformable blocks for fracture

Yongchang CAI, Hehua ZHU, Xiaoying ZHUANG

期刊论文

Calculation methods of the crack width and deformation for concrete beams with high-strength steel bars

Jianmin ZHOU, Shuo CHEN, Yang CHEN

期刊论文

Calculation method of radial stress and deformation on conic threaded connections with interference fit

Shoujun CHEN, Qiang LI, Qi AN,

期刊论文

Simulation of blast induced crater in jointed rock mass by discontinuous deformation analysis method

Youjun NING, Xinmei AN, Jun YANG, Guowei MA,

期刊论文

Rotation errors in numerical manifold method and a correction based on large deformation theory

Ning ZHANG, Xu LI, Qinghui JIANG, Xingchao LIN

期刊论文

Deformation control criterion of shield tunnel under lateral relaxation of soft soil

期刊论文

Deformation field and crack analyses of concrete using digital image correlation method

Yijie HUANG, Xujia HE, Qing WANG, Jianzhuang XIAO

期刊论文