基于Weibull分布的石砌体单轴受压损伤本构模型

石砌体的本构模型是石砌体力学计算和有限元数值模拟的重要基础和前提条件。为了深入研究石砌体单轴受压下的本构关系,基于损伤力学理论,应用双参数Weibull分布函数反映损伤变量,根据石砌体单轴受压应力-应变全过程曲线的特征条件确定其参数,推导并建立了石砌体单轴受压损伤本构模型,将已有试验数据验证本构模型的正确性,并将本构模型与典型的砌体本构模型进行对比分析,最后应用本构模型对已有石砌体拱桥试验进行有限元分析以验证本构模型的适用性。结果表明：所建模型与已有石砌体单轴受压试验结果吻合良好;所建模型验证了石砌体损伤演化的一般规律,符合典型的砌体本构模型的一般趋势;所建模型可应用于石砌体结构有限元分析计算,适用性良好。     

砂土速率相关黏性特性的有限元分析

根据复杂加载条件下饱和砂土排水平面应变压缩试验,分析了砂土的速率相关的黏性特性.试验发现砂土存在显著的加载速率效应、蠕变变形和应力松弛,并且在应变速率突变、蠕变或应力松弛之后,以新的应变速率重新加载时呈现出高刚度行为.针对砂土的变形强度特性提出了一种非线性有限元计算方法,砂土本构关系采用了三要素弹黏塑性本构模型.将有限元计算结果与试验结果进行比较,表明建议的有限元计算方法不仅可以较为精确地模拟砂土的平均应力-应变关系,同时也可以模拟包含变应变速率加载、蠕变加载、应力松弛加载的全过程黏塑特性.     

基于SPH方法的LY12-CZ铝合金平板鸟撞模型

为了得到更准确的飞机鸟撞分析模型,基于显式有限元分析程序PAM-CRASH建立了LY12-CZ铝合金平板的鸟撞数值模型.采用Johnson-Cook方程表述LY12-CZ材料的本构.LY12-CZ铝合金在4种不同应变率下的应力-应变曲线通过电子万能试验机和分离式霍普金森拉杆(SHTB)拉伸试验获得,对曲线进行拟合得到Johnson-Cook方程中的4个常数.基于光滑粒子流体动力学(SPH)方法建立了鸟体模型,引入Monaghan EOS方程来描述鸟体材料.针对所建立的鸟撞数值计算模型,开展相对应的鸟撞试验,获得测试点的应变,并将数值计算结果和试验结果进行对比.结果表明:计算应变与试验测得的应变吻合较好,验证了鸟体、铝合金本构模型以及鸟体高速冲击计算分析模型的合理性、可靠性.     

岩体拉破坏非线性分析有限元程序的编制及其算例

根据岩体拉破坏的本构关系建立了岩体拉破坏非线性分析的有限元程序,并用简单的算例证明了该有限元模型的合理性和程序编制的正确性·把该程序嵌入到一般的岩体弹性及弹塑性分析有限元程序中,较好地反映了岩体受拉应力作用的变形特征·     

不排水条件下全风化花岗岩残积土工程特性与本构模型

通过土工试验对不排水剪切条件下的饱和松散砂质土的工程特性进行了探讨 ,发现其在剪切时的应力 -应变关系呈现出加工软化特性 ,土体超过峰值强度后最终达到了变形的稳定状态 .基于稳定状态概念 ,将临界土力学理论与非线性应力 -应变关系相结合 ,建立了非线性应力 -应变 -临界状态本构模型 .采用香港钻石山地区全风化花岗岩残积土的不排水三轴试验结果 ,确定了有关模型参数 ,验证了所建议本构模型的合理性     

基于综合结构势的黄土结构性非线性本构模型研究

非线性本构模型由于其原理简单,计算方便,所以是当前工程界普遍采用的本构模型之一;但是当其应用到黄土区域工程计算时,由于结构性的存在,使得采用非饱和本构模型模拟出的结果与实际存在一定的差距。为了解决上述存在的问题,以黄土为研究对象,基于综合结构势的思想,首先分析了三轴压缩应力作用下的黄土的结构性宏观应力应变特性及其综合结构势的变化规律;进一步将综合结构势引入引入现有的非线性本构模型,建立了考虑结构性的黄土的非线性本构模型;最后通过与试验数据的对比分析,验证了该模型的合理性及预测结果的准确性。     

基于纤维模型的FRP约束混凝土圆柱本构模型研究

在OpenSees平台上采用纤维模型模拟FRP约束混凝土圆柱的受力性能时需要开发相应的本构模型.基于Jiang和Teng提出的分析型骨架本构模型,将不同峰值应力、应变计算公式的计算结果与试验结果进行比较,选择了更为精确的计算公式,并将其引入该骨架模型.该模型还考虑了箍筋对核心混凝土的约束作用,采用FRP极限环向抗拉应变折减系数得出FRP片材在环向受拉破坏时的极限拉应变.根据是否考虑钢筋的疲劳采用两种不同钢筋本构关系对试件进行模拟.采用该模型不但可以得到构件的轴向应力应变关系,还可以计算横向应变与轴向应力的关系,模拟结果与试验结果吻合较好.     

一种非共轴应变硬化本构模型数值应用及离心机试验验证

在土体的剪切变形过程中,当主应力方向产生旋转时,主应变增量方向与主应力方向之间存在显著的非共轴现象.同时,机动摩擦角、膨胀角随着累积塑性偏应变的增长而增加,土体具有应变硬化的特点.传统的弹塑性本构模型不能够反映上述现象对地基承载力特性的影响.为了能够对地基承载力问题进行合理的分析,建立了一种非共轴应变硬化模型,并将该模型运用到有限元计算中.通过与三轴试验和离心机模型试验结果进行对比,对该模型在数值应用中的合理性进行了验证.研究结果表明,该模型能够对不同围压下的应力-应变关系进行预测.对浅基础承载力问题进行研究时,非共轴应变硬化模型的计算结果比传统弹塑性本构模型更加接近于离心机试验结果,验证了该模型的数值应用合理性.     

Chaboche率相关本构模型的数值积分算法

为验证Chaboche率相关本构模型对循环塑性行为的描述能力,研究了有限元计算中本构关系的数值积分过程和Newton-Baphson迭代算法.编写了ABAQUS材料用户子程序UMAT,在此基础上对316不锈钢材料在600℃下的循环特性进行了有限元数值模拟.结果表明:该模型对材料率相关性、对称拉压循环特性及棘轮效应的描述...     

金属材料循环加载本构关系有限元模型的二次开发

金属材料多轴循环本构关系与加载路径强烈相关,只有建立路径相关的金属弹塑性本构关系模型,才能对复杂的多轴循环载荷下的机械零部件进行准确的应力应变分析和疲劳寿命预测。基于增量理论,建立金属材料弹塑性本构关系的有限元模型,并利用Ansys有限元软件下的UPFs对Ansys单元本构关系进行了二次开发。最后对二次开发的单元本构关系模型与Ansys自身材料库模型进行了算例对比,开发的单元本构关系模型计算结果准确可靠,可以进行金属材料循环加载下的应力应变分析。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with