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橡胶类材料大应变时明显硬化的本构分析 被引量:2
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作者 朱艳峰 刘锋 +1 位作者 黄小清 李丽娟 《暨南大学学报(自然科学与医学版)》 CAS CSCD 北大核心 2005年第1期98-99,102,共3页
 对不可压缩各向同性超弹性橡胶类材料引入一种应变能函数来模拟其增强效应.应变能函数中包含了应变不变量,且限制了最大主伸长.对均匀变形的单轴拉伸橡胶类材料进行了计算,实验表明,该函数较好地反映了Mooney-Rivlin型材料的增强效应.
关键词 橡胶类材料 极限伸长 材料硬化 本构分析
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长江三峡巴东县黄土坡前缘斜坡变形数据本构分析预测研究 被引量:1
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作者 王园 唐辉明 王沁 《地球科学(中国地质大学学报)》 EI CSCD 北大核心 1998年第6期635-638,共4页
应用数据本构分析方法,对三峡库区巴东县黄土坡前缘斜坡变形发展趋势进行了分析预测,阐明了数据本构分析预测对斜坡地质灾害的分析。
关键词 斜坡变形 数据本构分析 预测 黄土坡 地质灾害
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地质灾害问题的数据本构分析意义 被引量:1
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作者 王园 王沁 郑祖国 《自然灾害学报》 CSCD 1998年第1期46-52,共7页
本文结合上海市地面沉降和西安市地裂灾害问题,阐述了数据本构分析研究地质灾害问题的方法、步骤及意义。
关键词 地质灾害 数据本构分析 地裂灾害 地面沉降
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斜坡地质灾害成因问题数据本构分析
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作者 王园 唐辉明 +2 位作者 何蕴龙 王沁 郑祖国 《地质灾害与环境保护》 1998年第3期5-9,共5页
应用数据本构分析方法,以三峡库区巴东县黄土坡前缘斜坡变形成因问题为例,探讨数据本构分析方法对斜坡地质灾害成因问题的分析意义,丰富了对该类问题研究的手段。
关键词 斜坡 地质灾害 成因 数据本构分析 滑坡 泥石流
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Mg-4.4Li-2.5Zn-0.46Al-0.74Y合金高温变形流动应力、组织演变与本构分析 被引量:2
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作者 曹富荣 丁鑫 +1 位作者 项超 尚会会 《金属学报》 SCIE EI CAS CSCD 北大核心 2021年第7期860-870,共11页
采用多向锻造与轧制(MDFR)制备了Mg-4.4Li-2.5Zn-0.46Al-0.74Y合金,利用拉伸机、OM和XRD等研究了热拉伸流动应力、组织演变、本构模型与变形机理。结果表明,合金多向锻造晶粒细化机理为机械式剪切破碎与动态再结晶细化。合金在523~573 K... 采用多向锻造与轧制(MDFR)制备了Mg-4.4Li-2.5Zn-0.46Al-0.74Y合金,利用拉伸机、OM和XRD等研究了热拉伸流动应力、组织演变、本构模型与变形机理。结果表明,合金多向锻造晶粒细化机理为机械式剪切破碎与动态再结晶细化。合金在523~573 K时,热变形组织主要发生动态回复与动态再结晶;≥573 K时,热变形组织主要发生晶粒长大;在623 K发生由晶粒长大引起的应变硬化。合金退火组织由α(Mg)、β(Li)、Al_(2)Y、Al_(12)Mg_(17)、LiAl和Mg_(2)Y相组成。本构分析表明,合金应力指数为4.4,变形激活能为120.40 kJ/mol;623 K、1.67×10^(-4)s^(-1)条件下,对应240%延伸率的位错密度和数量与原子扩散计算表明,合金在该条件下的变形机理为晶格扩散控制的位错蠕变。晶粒长大模型确定该条件下的晶粒长大指数q=2,比例因子α’=0.2。 展开更多
关键词 MG-LI合金 热拉伸 显微组织 力学性能 本构分析 变形机理
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高强钢筋热压缩过程的本构分析及有限元模拟 被引量:9
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作者 闫洞旭 方实年 +2 位作者 蒲春雷 丁汉林 朱国辉 《中国冶金》 CAS 北大核心 2021年第3期50-58,共9页
为了研究Nb/V微合金化钢筋的热变形行为,采用Gleeble-3500热模拟机对Nb和Nb/V微合金化的20MnSi钢进行单轴热压缩试验。通过对其不同形变条件(变形温度和应变速率)下的真应力-应变曲线进行分析,建立可以表征20MnSiNb和20MnSiNbV钢应力、... 为了研究Nb/V微合金化钢筋的热变形行为,采用Gleeble-3500热模拟机对Nb和Nb/V微合金化的20MnSi钢进行单轴热压缩试验。通过对其不同形变条件(变形温度和应变速率)下的真应力-应变曲线进行分析,建立可以表征20MnSiNb和20MnSiNbV钢应力、应变、应变速率和温度四者关系的本构方程,并将该本构方程应用于有限元分析软件DEFORM 3D的材料模块中,对试验钢的热压缩过程进行数值模拟。结果表明,2种试验钢的热压缩过程均呈现了明显的动态再结晶特征,Nb或Nb/V微合金化均导致20MnSi钢的热变形激活能增加;有限元模拟表明压缩试样存在应变场和温度场分布不均匀现象,其中试样芯部相对于其他区域始终处于高应变、高应变速率和高形变温度的状态。在实际生产和研究中,对试样不同区域组织和性能的预测可参考模拟结果,分别进行探究。 展开更多
关键词 微合金化 20MNSI钢 热变形 本构分析 有限元模拟
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本构方程特性分析及板料成形中的模具补偿——在英国访问期间研究工作介绍
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作者 李柏林 《学术动态(成都)》 2001年第1期29-30,共2页
本文总结了作者在英国伯明翰(Bimingham)大学访问期间(1999.11.~2000.11.)所做的两项研究工作。(1)利用优化技术中的单调性分析方法对高温蠕变统一本构方程的特性进行了全面的分析,讨论了优化方法的选择条件,并利用进化规划对这一问题... 本文总结了作者在英国伯明翰(Bimingham)大学访问期间(1999.11.~2000.11.)所做的两项研究工作。(1)利用优化技术中的单调性分析方法对高温蠕变统一本构方程的特性进行了全面的分析,讨论了优化方法的选择条件,并利用进化规划对这一问题进行了优化。(2)参加了由英国空中客车公司资助的项目'利用有限元技术的回弹分析和高质量模具曲面描述' 展开更多
关键词 本构方程特性分析 板料成形 模具补偿 高温蠕变 板料回弹
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混凝土在多维应力状态下的损伤本构模型
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作者 吴建营 李杰 《结构工程师》 2003年第z1期1-6,共6页
已有的混凝土平面应力有限元分析均是利用单轴应力-应变本构关系,其中经验系数的选取带有相当的主观色彩,因此十分有必要建立混凝土在多轴应力特别是二维应力状态下的本构关系并直接应用于非线性分析.基于连续损伤力学的理论框架,作者... 已有的混凝土平面应力有限元分析均是利用单轴应力-应变本构关系,其中经验系数的选取带有相当的主观色彩,因此十分有必要建立混凝土在多轴应力特别是二维应力状态下的本构关系并直接应用于非线性分析.基于连续损伤力学的理论框架,作者建立了理论上较为完备、应用较为简单的确定性混凝土拉剪弹塑性损伤本构模型.模型数值模拟和已有试验结果的对比表明,本文建议模型能够很好的描述双轴应力条件下混凝土材料的弹性区域包络线以及强度包络线,同时应力-应变全过程结果和Kupfer (Kupfer et al.1969)的试验结果吻合良好,能够很好的模拟混凝土双轴受压强度的提高和双轴拉压应力状态下的"拉压软化效应",这对混凝土结构的非线性分析是非常重要的. 展开更多
关键词 本构关系 连续损伤力学 损伤本构模型 非线性分析
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Ni-Cr-Mo-B特厚板钢的热压缩变形行为 被引量:6
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作者 高志玉 潘涛 +2 位作者 王卓 刘国权 苏航 《材料热处理学报》 EI CAS CSCD 北大核心 2015年第9期148-155,共8页
利用Gleeble-3800热模拟试验机,研究了Ni-Cr-Mo-B特厚板钢在900~1150℃、应变速率为0.01~10 s-1、试样工程应变量为70%的热压缩变形行为。基于实验数据,使用回归分析的方法建立了Ni-Cr-Mo-B钢的双曲正弦Arrhenius型本构方程。采用应变... 利用Gleeble-3800热模拟试验机,研究了Ni-Cr-Mo-B特厚板钢在900~1150℃、应变速率为0.01~10 s-1、试样工程应变量为70%的热压缩变形行为。基于实验数据,使用回归分析的方法建立了Ni-Cr-Mo-B钢的双曲正弦Arrhenius型本构方程。采用应变硬化速率与应力关系曲线、实验流变曲线准确的确定了表征动态再结晶行为的重要特征参数:临界应力/应变、峰值应力/应变和稳态应力/应变。结果表明:Ni-Cr-Mo-B钢的热变形激活能(Q)为351074 J·mol-1;随着变形温度升高及应变速率减小,即Zener-Hollomon参数(Z)减小,各特征参数减小,有利于动态再结晶发生;临界应力与峰值应力比为0.89,临界应变与峰值应变之比为0.44。此外,基于Z参数,确定了Ni-Cr-Mo-B钢动态再结晶特征参数的数学预测模型。 展开更多
关键词 特厚板钢 本构分析 动态再结晶 应变硬化速率 特征参数
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EMPIRICAL STUDY ON CAPITAL STRUCTURE OF LISTED COMPANIES IN CHINESE STOCK MARKET 被引量:1
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作者 郝丽萍 谭庆美 《Transactions of Tianjin University》 EI CAS 2001年第3期172-177,共6页
Capital structure decision is an important issue of corporate finance.Theories show that,the corporate debt ratio is determined by many factors.This study conducts empirical work on capital structure theories,focusing... Capital structure decision is an important issue of corporate finance.Theories show that,the corporate debt ratio is determined by many factors.This study conducts empirical work on capital structure theories,focusing on the corporate data of Chinese listed companies,by considering the intrinsic characteristics,utilizing the principal factor analysis and the ridge regression method.Our results suggest that a firms debt ratio has a positive relationship with its size,profitability and operating risk and has a negative relationship with its growth and non debt tax shield,while the long term leverage has a positive relationship with its collateral value of assets. 展开更多
关键词 capital structure empirical study factor analysis ridge regression
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Analysis of microscopic pore structures of rocks before and after water absorption 被引量:6
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作者 Li Dejian Wang Guilian +5 位作者 Han Liqiang Liu Peiyu He Manchao Yang Guoxing Tai Qimin Chen Cheng 《Mining Science and Technology》 EI CAS 2011年第2期287-293,共7页
Hydrophilic characteristics of rocks are affected by their microscopic pore structures,which clearly change after water absorption.Water absorption tests and scanning electron microscopic(SEM) experiments on rock sa... Hydrophilic characteristics of rocks are affected by their microscopic pore structures,which clearly change after water absorption.Water absorption tests and scanning electron microscopic(SEM) experiments on rock samples,located at a site in Tibet,China,were carried out Changes of rock pore structures before and after water absorption were studied with the distribution of pore sizes and fractal characteristics of pores.The results show that surface porosities,fractal dimensions of pores and the complexity of pore structures increased because the number of new small pores produced increased or the original macropore flow channels were expanded after rocks absorbed water.There were points of inflection on their water absorption curves.After water absorption of other rocks,surface porosities and fractal dimensions of pores and complexity of pore structures decreased as the original pore flow channels became filled.Water absorption curves did not change.Surface porosity and the pore fractal dimensions of rocks have good linear relationships before and after water absorption. 展开更多
关键词 Hydrophilic characteristics Pore structures Pore size distribution Pore fractal characteristics
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蠕变模型及其应用 被引量:2
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作者 李东平 《石油化工设计》 CAS 2018年第3期5-7,12,共4页
结合石油化工装置设计中常遇到的高温工况,对此工况下金属蠕变的数学、力学模型及其应用进行了讨论。给出了材料的蠕变曲线,对Maxwell模型、Kelvin模型和Maxwell-kelvin模型进行了研究,给出了高温蠕变管道的应力分析方法和评判标准。
关键词 蠕变极限持久强度和塑性本构关系应力分析
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Parameter fitting of constitutive model and FEM analysis of solder joint thermal cycle reliability for lead-free solder Sn-3.5Ag 被引量:1
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作者 周萍 胡炳亭 +1 位作者 周孑民 杨莺 《Journal of Central South University》 SCIE EI CAS 2009年第3期339-343,共5页
The experimental tests of tensile for lead-flee solder Sn-3.5Ag were performed for the general work temperatures range from 11 to 90 ℃ and strain rate range from 5 × 10^-5 to 2 × 10^-2s^-1, and its stress--... The experimental tests of tensile for lead-flee solder Sn-3.5Ag were performed for the general work temperatures range from 11 to 90 ℃ and strain rate range from 5 × 10^-5 to 2 × 10^-2s^-1, and its stress--strain curves were compared to those of solder Sn-37Pb. The parameters in Anand model for solder Sn-3.5Ag were fitted based on experimental data and nonlinear fitting method, and its validity was checked by means of experimental data. Furthermore, the Anand model was used in the FEM analysis to evaluate solder joint thermal cycle reliability. The results show that solder Sn-3.5Ag has a better creep resistance than solder Sn-37Pb. The maximum stress is located at the upper right comer of the outmost solder joint from the symmetric center, and thermal fatigue life is predicted to be 3.796 × 10^4 cycles under the calculated conditions. 展开更多
关键词 lead free solder Sn-3.5Ag alloy Sn-37Pb alloy constitutive model TENSILE FEM analysis thermal cycle reliability
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2099 Al-Li合金热变形本构模型(英文) 被引量:8
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作者 张飞 沈健 +1 位作者 闫晓东 孙建林 《稀有金属材料与工程》 SCIE EI CAS CSCD 北大核心 2014年第6期1312-1318,共7页
采用高温等温压缩试验并利用修正后的流变曲线,研究了2099Al-Li合金在变形温度为300~500℃,应变速率为O.001~10s^-1,变形量(真应变)为0.7条件下的流变行为。结果表明:可用包含Z参数的双曲正弦形式来表征变形温度和应变速率对2... 采用高温等温压缩试验并利用修正后的流变曲线,研究了2099Al-Li合金在变形温度为300~500℃,应变速率为O.001~10s^-1,变形量(真应变)为0.7条件下的流变行为。结果表明:可用包含Z参数的双曲正弦形式来表征变形温度和应变速率对2099Al—Li合金热变形行为的影响;将应变作为影响因素,求解了不同应变量下的材料常数,并构建了考虑应变的本构模型;统计分析结果表明,除了在变形温度为300℃,应变速率为10S。之外,该模型能够很好的预测2099Al-Li合金高温流变行为。 展开更多
关键词 2099 AL-LI合金 本构分析 补偿应变 流变应力预测
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Stability analysis of slope in strain-softening soils using local arc-length solution scheme 被引量:3
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作者 WANG Xiang-rong RONG Qi-guo +1 位作者 SUN Shu-li WANG Hui 《Journal of Mountain Science》 SCIE CSCD 2017年第1期175-187,共13页
Soils with strain-softening behavior — manifesting as a reduction of strength with increasing plastic strain — are commonly found in the natural environment. For slopes in these soils,a progressive failure mechanism... Soils with strain-softening behavior — manifesting as a reduction of strength with increasing plastic strain — are commonly found in the natural environment. For slopes in these soils,a progressive failure mechanism can occur due to a reduction of strength with increasing strain. Finite element method based numerical approaches have been widely performed for simulating such failure mechanism,owning to their ability for tracing the formation and development of the localized shear strain. However,the reliability of the currently used approaches are often affected by poor convergence or significant mesh-dependency,and their applicability is limited by the use of complicated soil models. This paper aims to overcome these limitations by developing a finite element approach using a local arc-length controlled iterative algorithm as the solution strategy. In the proposed finite element approach,the soils are simulated with an elastoplastic constitutive model in conjunction with the Mohr-Coulomb yield function. The strain-softening behavior is represented by a piece-wise linearrelationship between the Mohr-Coulomb strength parameters and the deviatoric plastic strain. To assess the reliability of the proposed finite element approach,comparisons of the numerical solutions obtained by different finite element methods and meshes with various qualities are presented. Moreover,a landslide triggered by excavation in a real expressway construction project is analyzed by the presented finite element approach to demonstrate its applicability for practical engineering problems. 展开更多
关键词 Strain-softening Progressive failure Slope stability Local arc-length scheme Numerical simulation
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Managerial Compensation Program and Capital Structure: An Empirical Study of Brazilian Companies
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作者 Maria Aparecida Gouvea Jose Roberto F. Savoia Michele N. Juca Ligia N. C. Fonseca 《Journal of Modern Accounting and Auditing》 2012年第2期147-160,共14页
The agency theory indicates the existence of costs as a way to mitigate conflicts between shareholders and managers, including: managerial compensation program, acquisition of shares by managers, monitoring of execut... The agency theory indicates the existence of costs as a way to mitigate conflicts between shareholders and managers, including: managerial compensation program, acquisition of shares by managers, monitoring of executives, and controlling shareholders. This study aims to determine the relevance of some variables related to compensation programs and of other determinants of the corporate debt level. It has considered a sample of 89 firms, which were analyzed through logistic regression (cross section). The model created has indicated a level of predictive assertiveness of approximately 87%. 展开更多
关键词 managerial compensation programs agency conflicts logistic regression
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Capital Structure and Natural Rate of Unemployment: An Empirical analysis
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作者 Liu hui 《International English Education Research》 2014年第10期47-50,共4页
The model based on Marxism economics such as capital structure ,capital deposit and capital cycles measure directly natural rate of the unemployment. The natural rate of unemployment is decided by the capital per work... The model based on Marxism economics such as capital structure ,capital deposit and capital cycles measure directly natural rate of the unemployment. The natural rate of unemployment is decided by the capital per worker, capital structure and average wage. According to the model the natural rate of the unemployment is empirical from 1991 to 2009.the result shows that the ascendant trend is very obvious. At last, according to the model, adjusting economic structure and regulating income distribution can reduce natural rate of unemployment. 展开更多
关键词 Natural rate of unemployment capital structure capital per worker
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Self-Dealing Among Convergence and Path-Dependency Opportunities: An Empirical Analysis of Regulatory From Six European Countries
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作者 Rosa Vinciguerra Nadia Cipullo 《Journal of Modern Accounting and Auditing》 2014年第6期629-651,共23页
Self-dealing refers to all kinds of transactions and operations diverting value from a company to corporate controllers. In order to tackle self-dealing, academics and regulators have emphasised the legal tools. Howev... Self-dealing refers to all kinds of transactions and operations diverting value from a company to corporate controllers. In order to tackle self-dealing, academics and regulators have emphasised the legal tools. However, there is a divergence between those supporting the existence of a benchmark model towards which to converge (convergence hypothesis) and those underscoring the importance of socio-economic factors on the efficacy of governance rules (path-dependency view). The aim of this paper is to join in the convergence vs. path-dependency debate by focusing on the efficiency of mandatory rules and investigating their effectiveness. Considering the current market integration, the traditional cost-benefit analysis has been extended in order to embrace costs specifically associated to the issue of domestic rules in a global scenario. This analysis supports the convergence view and encourages at least a partial and gradual adjustment of national legislations towards the prevailing Anglo-Saxon model. In order to test this hypothesis, an examination of the self-dealing regulatory (on conflict of interests and self-dealing) adopted in some Western (Germany, Italy, and the United Kingdom (UK)) and Eastern (Czech Republic, Hungary, and Poland) European countries has been conducted. 展开更多
关键词 self-dealing Europe transition economies International Accounting Standards (IAS) 24
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弥散强化6XXX铝合金热变形行为研究 被引量:3
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作者 王孝国 张孝元 +2 位作者 孙瑞娟 王斌 王嘉伟 《特种铸造及有色合金》 CAS 北大核心 2021年第9期1114-1118,共5页
对均匀化态含Mn/Cr弥散强化6XXX铝合金(WQ合金)在不同变形温度和应变速率下进行轴向热压缩试验。应用双曲正弦本构方程求得合金材料参数和激活能;基于动态材料模型获得变形合金热加工图;根据热加工图确定安全加工窗口,优化变形参数;WQ... 对均匀化态含Mn/Cr弥散强化6XXX铝合金(WQ合金)在不同变形温度和应变速率下进行轴向热压缩试验。应用双曲正弦本构方程求得合金材料参数和激活能;基于动态材料模型获得变形合金热加工图;根据热加工图确定安全加工窗口,优化变形参数;WQ合金安全加工区域动态软化机制主要为动态回复,亚晶旋转和(亚)晶界迁移受阻于α弥散相;加工失稳区微观组织存在裂纹,主要与微孔形成和第二相开裂、脱相有关。 展开更多
关键词 6XXX铝合金 热变形 本构分析 热加工图 α弥散相
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