平面应变下的主应力比对微孔洞损伤演化行为的影响

通过有限元计算,分析平面应变下的主应力比对微孔洞损伤演化行为的影响.计算结果表明,三向应力度q相同时,不同的主应力比2σ/1σ会引起不同的孔洞长大和聚合行为,从而使开裂路径和断裂时的应变不同.当2σ/1σ>1时,最大主应力为2σ,由孔洞长大和聚合所决定的开裂路径倾向于同2σ方向垂直.当2σ/1σ<1时,最大主应力为σ1,开裂路径倾向于同1σ方向垂直.随主应力比2σ/1σ的增加,孔洞面积分数fa随主应变1ε1的增加速率变大,断裂时的主应变(1ε1)f降低.因此在分析应力状态对材料的损伤断裂行为的影响及建立相应的力学模型时,不仅要考虑三向应力度σm/eσ,而且要考虑不同主应力比2σ/1σ的影响.     

有限元计算应力模拟实验光弹性等差条纹图

提出用有限元计算应力模拟光弹性等差条纹图像的方法，介绍了由计算应力计算图像显示点应力的算法。通过主应力差与光弹性等差条纹的关系获得了模拟条纹图。模拟条纹图的灰度值可由数字图像卡快速全场显示，实现了计算应力的光弹性应力等差条纹图的模拟。所提出的新思路为计算结果与实验结果进行全场定量比较提供了新的途径。     

有限元计算应力模拟实验光弹性等差条纹图

提出用有限元计算应力模拟光弹性等差条纹图像的方法，介绍了由计算应力计算图像显示点应力的算法．通过主应力差与光弹性等差条纹的关系获得了模拟条纹图．模拟条纹图的灰度值可由数字图像卡快速全场显示，实现了计算应力的光弹性应力等差条纹图的模拟．所提出的新思路为计算结果与实验结果进行全场定量比较提供了新的途径     

三向非等压应力场下围岩主应力差与塑性区分布关系研究

首先,以弹性理论为基础推导出考虑巷道轴向应力影响的主应力差解析式,通过变化水平侧压比、轴向侧压比研究完全弹性条件时不同应力场下主应力差分布形态演化规律。其次,推导出考虑轴向应力作用的围岩塑性区近似解,研究不同应力环境下围岩的塑性区形态演化规律。最后,对比分析主应力差及塑性区形态特征,研究二者分布形态的对应关系,并通过数值模拟验证理论分析的正确性。研究结果表明：在弹性理论下,三向应力场条件的主应力差值分布会呈现圆形、椭圆形、蝶形3种形态的演化规律;在考虑巷道塑性破坏的情况下,主应力差值在σx、σz较小一侧形成峰值壳,在较大一侧形成卸压壳。在不同水平侧压比及轴向侧压比情况下,围岩塑性区形态会呈现圆形—椭圆形、椭圆形—蝶形、蝶形恶性扩展3个阶段的演化过程。巷道主应力差的分布形态在一定程度上可以反映塑性区形态,主应力差和塑性区在相同应力条件下的形态特征具有逐一对应关系,且二者形态在很大程度上由水平侧压比决定,轴向侧压比对塑性区形态影响较小。160206回风巷在偏转式主应力差集中区形成非对称异化特征。本文基于分析及现场破坏情况提出的联合协同支护技术在现场应用效果较好。     

原岩应力分布状态在地下巷道设计中的应用

地下巷道开挖后，其周围应力产生重新分布，形成二次应力状态，产生应力集中。利用二次应力函数σ＝ｆ（σ０），推导出空间二次应力函数的表达式。通过实例计算，研究了不同原岩应力状态下巷道断面上应力椭圆形状和二次应力的大小，进而得出巷道的走向与最大主应力的关系。     

冷拔管时拔制力计算的研究

建立近似的力平衡条件、近似的塑性条件,应用边界条件联解上述方程,得到空拔时应力状态系数σ拉/σ_s,以便计算空拔管时各道次的拔制力。     

基于Hoek-Brown准则点安全系数的边坡稳定性分析

为了采用Hoek-Brown准则分析边坡各部位的稳定程度,通过理论分析,推导Hoek-Brown参数表征的点安全系数(Fp)函数;利用FLAC3D软件建立边坡数值计算模型,编制相应Hoek-Brown点安全系数程序,分析材料参数和应力变化的影响.研究结果表明:采用自编程序计算的Fp≤1区域与采用FLAC3D软件计算的塑性区分布范围大致相同,并且点安全系数的判定标准能够表征各单元的破坏程度,优于塑性区判定标准;随着单元损伤程度的加大,点安全系数Fp逐渐减小;随着地质强度指标GSI增大,Fp逐渐增大,两者之间的关系符合3次多项式分布;Fp随完整岩石的单轴压缩强度σci的增大而增大;最大主应力σ1增大引起Fp逐渐减小,两者表现出显著的双曲线分布规律;Fp随最小主应力σ3的增大而增大,这与工程实际情况相符.     

关于光塑性研究中的若干基本问题

本文综合阐述和讨论了关于光塑性中的若干基本问题，并根据已有的应力－光学 定律．探讨和建议了光塑性应力分析计算的基本方法．     

粗粒料广义塑性模型对不同应力路径适应性研究

结合两种不同岩性的粗粒料在等σ1、等σ3、等p以及等应力比应力路径下的大型三轴试验和侧限压缩试验成果,研究了粗粒料广义塑性模型对不同应力路径的适应性.结果表明:广义塑性模型很好地反映了粗粒料变形的应力路径相关性.同时根据Roadford坝坝料的三轴试验结果得到的模型参数,对大坝进行了有限元数值模拟,计算得到的大坝填筑后的变形与实际监测结果吻合较好.表明广义塑性模型也能较好地反映土石坝施工期应力路径对坝体变形的影响.     

叶片有限元分析中弹塑性过渡区应力奇异产生原因及解决方法

采用弹塑性有限元法、借助大型商业有限元软件对汽轮机叶片进行应力分析时,弹塑性过渡区应力的计算值有时会高于塑性区应力的计算值,即会产生应力奇异现象。为分析产生这一现象的原因,以8节点六面体单元为例,研究了有限元法计算应力的过程,并在理想弹塑性的条件下,采用有限元法和解析法计算了弹塑性过渡区单元节点应力。研究发现,有限元法通常采用高斯积分点应力值外推插值法得到单元节点应力,当单元一部分位于弹性区、另一部分位于塑性区时,这种外插算法会导致节点应力计算值高于结构的实际应力,甚至超出理想弹塑性材料的屈服极限,从而造成应力奇异。研究表明,在叶片弹塑性的有限元分析中,采用相邻高斯积分点应力加权平均的方法计算单元节点应力,可有效避免弹塑性过渡区应力产生奇异的现象。     

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.     

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     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

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     

Journal of Donghua University ( English Edition) Contents of Volume 31

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