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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    

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    

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    

Hypoplastic constitutive modeling of wetting deformation of weathered rockfill materials

Erich BAUER, Zhongzhi FU, Sihong LIU,

《结构与土木工程前沿(英文)》 2010年 第4卷 第1期   页码 78-91 doi: 10.1007/s11709-010-0011-8

摘要: The wetting deformation of weathered rockfill materials has been attracting growing attention from both engineers and scientists. The importance of realistic predictions of wetting deformations for high earth and rockfill dams is a strong motivation to establish a suitable constitutive model. Recently, the hypoplastic constitutive model by Gudehus and Bauer was extended by introducing solid hardness depending on the state of weathering. The extended model takes into account the influence of the current density, the effective stress state, the rate of deformation, and the time dependent process of degradation of the solid hardness. In the present paper, the performance of this model is evaluated by comparing numerical simulations with experiments obtained from a water sensitive rockfill material. In particular, triaxial compression paths and creep deformation under deviatoric stress states are considered. Finally, the constitutive model proposed is used to study the influence of a degradation of the solid hardness on the long term behavior of a hypothetical fill dam.

关键词: rockfill dams     weathered granular materials     hypoplasticity     solid hardness     creep     stress relaxation    

Formation mechanism and modeling of surface waviness in incremental sheet forming

《机械工程前沿(英文)》 2022年 第17卷 第2期 doi: 10.1007/s11465-022-0679-1

摘要: Improving and controlling surface quality has always been a challenge for incremental sheet forming (ISF), whereas the generation mechanism of waviness surface is still unknown, which impedes the widely application of ISF in the industrial field. In this paper, the formation mechanism and the prediction of waviness are both investigated through experiments, numerical simulation, and theoretical analysis. Based on a verified finite element model, the waviness topography is predicted numerically for the first time, and its generation is attributed to the residual bending deformation through deformation history analysis. For more efficient engineering application, a theoretical model for waviness height is proposed based on the generation mechanism, using a modified strain function considering deformation modes. This work is favorable for the perfection of formation mechanism and control of surface quality in ISF.

关键词: surface waviness     incremental sheet forming     numerical simulation     formation mechanism     deformation history    

Finite element modeling of counter-roller spinning for large-sized aluminum alloy cylindrical parts

Dawei ZHANG, Fan LI, Shuaipeng LI, Shengdun ZHAO

《机械工程前沿(英文)》 2019年 第14卷 第3期   页码 351-357 doi: 10.1007/s11465-019-0528-z

摘要: Counter-roller spinning (CRS), where the mandrel is replaced by rollers, is an effective means of manufacturing large-sized, thin-walled, cylindrical parts with more than 2500 mm diameter. CRS is very complex because of multi-axis rotation, multi-local loading along the circumference, and radial-axial compound deformation. Analytical or experimental methods cannot fully understand CRS. Meanwhile, numerical simulation is an adequate approach to investigate CRS with comprehensive understanding and a low cost. Thus, a finite element (FE) model of CRS was developed with the FORGE code via meshing technology, material modeling, determining the friction condition, and so on. The local fine mesh moving with the roller is one of highlights of the model. The developed 3D-FE model was validated through a CRS experiment by using a tubular blank with a 720 mm outer diameter. The developed 3D-FE model of CRS can provide a basis for parameter optimization, process control, die design, and so on. The data on force and energy predicted by the 3D-FE model can offer reasonable suggestions for determining the main mechanical parameters of CRS machines and selecting the motors. With the predicted data, an all-electric servo-drive system/machine with distributed power was designed in this work for CRS with four pairs of rollers to manufacture a large-sized, thin-walled, cylindrical part with 6000 mm diameter.

关键词: large-sized cylindrical part     counter-roller spinning     aluminum alloy     finite element method     distributed power    

Numerical modeling of current-induced scour around multi-wall foundation using large-eddy simulation

《结构与土木工程前沿(英文)》 2023年 第17卷 第4期   页码 546-565 doi: 10.1007/s11709-023-0943-4

摘要: Scouring is one of the primary triggers of failure for bridges across rivers or seas. However, research concerning the scour mechanism of multi-wall foundations (MWFs) remains scarce, hindering the further application of MWFs. In this study, for the first time, the scouring effect caused by unidirectional flow around MWFs was examined numerically using FLOW-3D involving a large-eddy simulation. Initially, the applicability of the scouring model and input parameters was validated using a case study based on published measured data. Subsequently, the scouring effects of four MWFs with different wall arrangements and inflow angles, including the flow field analysis and scour pit and depth, were investigated thoroughly. It was found that the maximum scour depth of MWFs with an inflow angle of 0° was smaller than that of those with an inflow angle of 45°, regardless of the wall arrangement. Meanwhile, changing the inflow angle significantly affects the scour characteristics of MWFs arranged in parallel. In practical engineering, MWFs arranged in parallel are preferred considering the need for scouring resistance. However, a comparative analysis should be performed to consider comprehensively whether to adopt the form of a round wall arrangement when the inflow angle is not 0° or the inflow direction is changeable.

关键词: multi-wall foundation     current-induced scour     bridge foundation     large-eddy simulation     numerical analysis    

Modeling of large-deflection links for compliant mechanisms

Zhonglei FENG, Yueqing YU, Wenjing WANG,

《机械工程前沿(英文)》 2010年 第5卷 第3期   页码 294-301 doi: 10.1007/s11465-010-0019-8

摘要: The traditional pseudo-rigid-body model (PRBM) has one degree of freedom (DOF) and performs a good simulation to the tip locus of flexible links for compliant mechanisms on the basis of a parametric approximation method. In this study, a new approach of a two-DOF PRBM is proposed to simulate both the tip locus and tip deflection angle of large-deflection links for compliant mechanisms on the basis of the angular deflection approximation technique. A linear regression for the spring stiffness coefficient of the 2R PRBM using the optimization technique is presented. The advantage of the new model is well illustrated through a numerical comparison between the 1R and the 2R PRBM.

关键词: compliant mechanism     pseudo-rigid-body model (PRBM)     large-deflection link     angular deflection approximation    

Topicmodeling for large-scale text data

Xi-ming LI,Ji-hong OUYANG

《信息与电子工程前沿(英文)》 2015年 第16卷 第6期   页码 457-465 doi: 10.1631/FITEE.1400352

摘要: This paper develops a novel online algorithm, namely moving average stochastic variational inference (MASVI), which applies the results obtained by previous iterations to smooth out noisy natural gradients. We analyze the convergence property of the proposed algorithm and conduct a set of experiments on two large-scale collections that contain millions of documents. Experimental results indicate that in contrast to algorithms named ‘stochastic variational inference’ and ‘SGRLD’, our algorithm achieves a faster convergence rate and better performance.

关键词: Latent Dirichlet allocation (LDA)     Topic modeling     Online learning     Moving average    

Modeling of dynamic response of poroelastic soil layers under wave loading

Mehmet Bar?? Can üLKER

《结构与土木工程前沿(英文)》 2014年 第8卷 第1期   页码 1-18 doi: 10.1007/s11709-014-0233-2

摘要: In this paper, the dynamic response of saturated and layered soils under harmonic waves is modeled using the finite element method. The numerical results are then verified by corresponding analytical solutions which are also developed by the author. The equations governing the dynamics of porous media are written in their fully dynamic form and possible simplifications are introduced based on the presence of inertial terms associated with solid and fluid phases. The response variations are presented in terms of pore water pressure and shear stress distributions within the layers. It is determined that a set of non-dimensional parameters and their respective ratios as a result of layering play a major role in the dynamic response.

关键词: dynamic response of soils     coupled flow-deformation     finite elements     analytical solution     harmonic waves    

Piezoelectric inertial robot for operating in small pipelines based on stick-slip mechanism: modeling

《机械工程前沿(英文)》 2022年 第17卷 第3期 doi: 10.1007/s11465-022-0697-z

摘要: Small pipes exist in industrial and biomedical fields, and require microrobots with high operational precision and large load capacity to inspect or perform functional tasks. A piezoelectric inertial pipeline robot using a “stick-slip” mechanism was proposed to address this requirement. In this study, the driving principle of the proposed robot was analyzed, and the strategy of the design scheme was presented. A dynamics model of the stick-slip system was established by combining the dynamics model of the driving foot system and the LuGre friction model, and the simulation analysis of the effect of system parameters on the operating trajectory was performed. An experimental system was established to examine the output characteristics of the proposed robot. Experimental results show that the proposed pipeline robot with inertial stick-slip mechanism has a great load capacity of carrying 4.6 times (70 g) its own mass and high positioning accuracy. The speed of the pipeline robot can reach up to 3.5 mm/s (3 mm/s) in the forward (backward) direction, with a minimum step distance of 4 μm. Its potential application for fine operation in the pipe is exhibited by a demonstration of contactless transport.

关键词: pipeline robot     piezoelectric     inertial drive     stick-slip     large load capacity     dynamics model     small pipeline    

Key point selection in large-scale FBG temperature sensors for thermal error modeling of heavy-duty CNC

Jianmin HU, Zude ZHOU, Quan LIU, Ping LOU, Junwei YAN, Ruiya LI

《机械工程前沿(英文)》 2019年 第14卷 第4期   页码 442-451 doi: 10.1007/s11465-019-0543-0

摘要: Thermal error is one of the main factors that influence the machining accuracy of computer numerical control (CNC) machine tools. It is usually reduced by thermal error compensation. Temperature field monitoring and key temperature measurement point (TMP) selection are the bases of thermal error modeling and compensation for CNC machine tools. Compared with small- and medium-sized CNC machine tools, heavy-duty CNC machine tools require the use of more temperature sensors to measure their temperature comprehensively because of their larger size and more complex heat sources. However, the presence of many TMPs counteracts the movement of CNC machine tools due to sensor cables, and too many temperature variables may adversely influence thermal error modeling. Novel temperature sensors based on fiber Bragg grating (FBG) are developed in this study. A total of 128 FBG temperature sensors that are connected in series through a thin optical fiber are mounted on a heavy-duty CNC machine tool to monitor its temperature field. Key TMPs are selected using these large-scale FBG temperature sensors by using the density-based spatial clustering of applications with noise algorithm to reduce the calculation workload and avoid problems in the coupling of TMPs for thermal error modeling. Back propagation neural network thermal error prediction models are established to verify the performance of the proposed TMP selection method. Results show that the number of TMPs is reduced from 128 to 5, and the developed model demonstrates good prediction effects and strong robustness under different working conditions of the heavy-duty CNC machine tool.

关键词: thermal error     heavy-duty CNC machine tools     FBG     key TMPs     prediction model    

基于Agent的军用大型复杂系统建模与仿真

李宏刚,吕辉,刘兴堂

《中国工程科学》 2004年 第6卷 第8期   页码 40-44

摘要:

大型复杂系统是21世纪的核心技术之一,而军用复杂系统是各发达国家优先考虑的发展对象。在此背景下,简述了Agent的组成和原理,并对Agent用于军用复杂系统的建模过程进行了深入细致的分析,给出了复杂系统仿真模型和仿真结果,对仿真结果进行了分析。

关键词: 复杂系统     Agent     建模与仿真    

大直径盾构侧穿地铁站的变形预测与实测结果分析

张继清,索晓明

《中国工程科学》 2010年 第12卷 第12期   页码 18-22

摘要:

通过数值计算方法对北京地下直径线侧穿地铁2号线某车站的结构变形进行预测,并将预测值与实测值进行对比和差异性原因分析,以期对类似工程预测变形、指定控制指标有一定指导作用。

关键词: 大直径盾构     地铁车站     变形预测     监测     数值分析    

大而复杂形变区域中的精确三维形变反演——基于偏移的相位解缠和改进的多孔径SAR干涉测量集成技术在2016年熊本地震中的应用 Article

Won-Kyung Baek, Hyung-Sup Jung

《工程(英文)》 2020年 第6卷 第8期   页码 927-935 doi: 10.1016/j.eng.2020.06.012

摘要:

常规合成孔径雷达(synthetic aperture radar, SAR)干涉测量(InSAR)已成功用于精确测量雷达视线(line-of-sight, LOS)方向上的表面形变,而多孔径SAR干涉技术(multiple-aperture SAR interferometry, MAI)可以用于精确测量沿轨迹(along-track, AT)方向的表面形变。InSAR和MAI方法的集成可以精确测量干涉对中的二维(two-dimensional, 2D)形变;最近,升降轨联合解算使得人们可以观测到精确的三维(three-dimensional, 3D)形变。精确的3D形变测量已用于更好地了解地质事件,如地震和火山喷发。与2016年熊本地震有关的地表形变在断层线附近较大且复杂,因此精确的3D形变反演尚未展开。本研究的目的是:①通过对基于偏移的相位解缠和改进的多孔径SAR干涉图进行集成,在大而复杂的形变区域中进行精确3D形变反演的可行性测试;②观测与2016年熊本地震有关的甚至包含断层线附近的3D形变场。3D形变反演使用了两组升轨对和一组高级陆地观测卫星2(Advanced Land Observing Satellite-2, ALOS-2)相控阵型L波段合成孔径雷达2(Phased Array-type L-band Synthetic Aperture Radar-2, PALSAR-2)降轨干涉对。11个原位全球定位系统(global positioning system, GPS)测站的观测被用于验证3D形变的测量精度。3D形变测量在东、北和垂直方向上分别达到大约2.96 cm、3.75 cm和2.86 cm的精度。结果表明,即使在形变大而复杂的情况下,通过集成改进方法来测量精确的3D形变仍具有可行性。

关键词: 合成孔径雷达(SAR)     常规SAR干涉测量(InSAR)     多孔径SAR干涉技术(MAI)     ALOS-2 PALSAR-2     三维形变反演     2016年熊本地震    

标题 作者 时间 类型 操作

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

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

Hypoplastic constitutive modeling of wetting deformation of weathered rockfill materials

Erich BAUER, Zhongzhi FU, Sihong LIU,

期刊论文

Formation mechanism and modeling of surface waviness in incremental sheet forming

期刊论文

Finite element modeling of counter-roller spinning for large-sized aluminum alloy cylindrical parts

Dawei ZHANG, Fan LI, Shuaipeng LI, Shengdun ZHAO

期刊论文

Numerical modeling of current-induced scour around multi-wall foundation using large-eddy simulation

期刊论文

Modeling of large-deflection links for compliant mechanisms

Zhonglei FENG, Yueqing YU, Wenjing WANG,

期刊论文

Topicmodeling for large-scale text data

Xi-ming LI,Ji-hong OUYANG

期刊论文

Modeling of dynamic response of poroelastic soil layers under wave loading

Mehmet Bar?? Can üLKER

期刊论文

Piezoelectric inertial robot for operating in small pipelines based on stick-slip mechanism: modeling

期刊论文

Key point selection in large-scale FBG temperature sensors for thermal error modeling of heavy-duty CNC

Jianmin HU, Zude ZHOU, Quan LIU, Ping LOU, Junwei YAN, Ruiya LI

期刊论文

基于Agent的军用大型复杂系统建模与仿真

李宏刚,吕辉,刘兴堂

期刊论文

大直径盾构侧穿地铁站的变形预测与实测结果分析

张继清,索晓明

期刊论文

大而复杂形变区域中的精确三维形变反演——基于偏移的相位解缠和改进的多孔径SAR干涉测量集成技术在2016年熊本地震中的应用

Won-Kyung Baek, Hyung-Sup Jung

期刊论文