弹塑性双材料界面裂纹尖端场一阶项分析

详细分析了弹塑性材料与弹性材料或另一硬化指数ｎ不同的弹塑性材料固结时，界面裂纹尖端场渐近展开中一阶项的力学意义，给出由Ｊ积分和应力三轴度Ｑ两个参数共同确定应力和位移分布的条件。     

混杂纤维水泥基复合材料断裂分析

基于纤维水泥基材料的桥联法则（桥联应力-裂纹张开位移关系）和K叠加原理,建立了混杂纤维水泥基复合材料的桥联裂缝模型,并针对三点受弯梁建立了简化的断裂分析模型．桥联裂缝模型能够描述混杂纤维水泥基复合材料断裂全过程的裂缝扩展规律,灵活地分析不同纤维对断裂韧度的贡献,并可以计算混杂纤维水泥基复合材料裂纹尖端应力强度因子、断裂韧度和临界缝长．     

含异侧偏置裂纹试件的冲击断裂试验

利用新型数字激光动态焦散线试验系统,分析了含异侧偏置裂纹有机玻璃(PMMA)试件破坏的时程特性和裂纹尖端扩展过程中的应力奇异性变化。得出该加载条件下试件的断裂韧度约为1.16 MN/m_3/2,异侧偏置裂纹间距对试件冲击断裂韧度没有明显影响。一定范围内,异侧偏置裂纹间距越大,裂纹扩展的对称性越明显。贯穿主裂纹的扩展路径上存在一个明显的应力变化转折点,此处裂纹尖端的应力集中程度加强,试件由以拉伸破坏为主过渡为拉伸、剪切复合破坏。次裂纹尖端发生明显应力释放的同时,主裂纹尖端的应力集中明显加强。裂纹扩展过程中,裂纹尖端的动态应力强度因子表现出明显的震荡变化,主裂纹相对于次裂纹裂尖奇异性更强。     

应力对混凝土断裂参数测定有效性的影响

对于线弹性材料,裂缝尖端平行于裂缝方向的T应力会影响裂缝的扩展方向和起裂断裂韧度,然而在混凝土类准脆性材料的断裂韧度测试中,无论是起裂断裂韧度还是失稳断裂韧度,T应力的影响却少有研究.以混凝土Ⅰ型断裂韧度测试常用的三点弯曲梁、楔入劈拉试件为对象,计算了裂缝尖端的T应力大小,并分析了其对裂缝扩展方向和断裂韧度的影响.分析计算结果表明:这些常用试件裂缝尖端的T应力相比于裂缝尖端控制因素应力强度因子K很小,不会影响裂缝扩展方向,保证了混凝土断裂失稳前一直处于Ⅰ型裂缝状态;另外,T应力对起裂断裂韧度和失稳断裂韧度的数值也不会产生影响,说明常用试件进行的混凝土断裂韧度确定方法是可靠有效的.     

非均质焊接接头的裂纹尖端拘束与J积分应用的可行性

采用弹塑性大变形有限元方法，分析了平面应力状太民下非均质焊接接头中以应力三轴度表征的裂纹尖端拘束。结果表明，接头中裂纹尖端拘束不能满足ＨＲＲ场要求而显示出与接头区配、裂纹长度和裂纹模型有关的复杂演化规律。因此，在焊接接头直接应用Ｊ积分作为断裂参量存有问。     

骨料最大粒径对混凝土双K断裂参数的影响

将线弹性断裂理论与虚拟裂缝模型相合,利用契入劈拉试件在实验中测得的最大荷载Ｐｍａｘ及对应的裂缝口开位移ｕｍｃ、断裂能Ｇｒ等参数得到了混凝土裂缝亚临界扩展量△ａｃ的解析解,据此计算了尺寸为４５０ｍｍ＊４５０ｍｍ＊４５０ｍｍ４组不同骨料最大粒径混凝土试件的起裂断裂韧度Ｋ＾ｉｎｉ Ｉｃ失稳断裂韧度Ｋ＾ｕｍ Ｉｃ（即双Ｋ断裂参数）及临界裂缝尖端张开位移ｕＩｃ、结果表明,Ｋ＾ｉｎｉ Ｉｃ、Ｋ＾ｕｎＩｃ随骨料     

橡胶增韧环氧树脂增韧机理的断裂力学研究

测量了 ＣＴＢＮ增韧环氧树脂的ＪＲ阻力曲线，利用理想弹塑性平面应变Ｉ型定常扩展裂纹的局部解及塑性介质中孔洞演化的Ｒｉｃｅ－Ｔｒａｃｅｙ方程，近似计算了裂纹尖端附近的孔洞化塑性体膨胀和残余应变能密度。通过对增韧机制的力学分析．得到定常扩展裂纹与起裂状态时的断裂韧性差值与 ＣＴＢＮ体积分数及材料断裂应变的关系式，它对环氧基材料的增韧设计有一定的指导意义。     

静载作用下含中心裂纹锈蚀钢板断裂性能退化机理与退化规律

以带中心裂纹的锈蚀钢板为研究对象,运用断裂力学的理论和参量,对锈蚀钢板断裂性能的退化机理与退化规律进行研究,建立了锈蚀钢材残余断裂韧度退化的经验模型.结果表明,锈蚀会导致应力强度因子的幅值增加,增大裂纹尖端应力场和位移场的强度,加速既有裂纹的扩展.对于未锈蚀模型和均匀锈蚀模型,裂纹尖端应力强度因子在厚度方向上从模型内部到模型表面逐渐减小;对于点蚀模型,裂纹尖端应力强度因子在厚度方向上从模型内部到表面锈坑底部逐渐增大.锈蚀还会影响J积分-荷载曲线,使J积分值更快达到其临界值,导致钢板断裂提前发生.断裂韧度退化的经验模型结果与断裂试验结果较为符合.     

T应力对岩石断裂韧度及扩展路径的影响

为了准确预测岩石类材料复合断裂韧度及裂纹扩展路径,提出结合T应力的修正最大周向应力断裂判据.该修正最大周向应力断裂判据是采用双参数模型(应力强度因子K和T应力)来描述岩石断裂的行为,对岩石类材料复合断裂进行理论计算和实验.结果表明:软岩半圆盘实验所得断裂韧度与传统最大周向应力断裂判据预测结果有较大误差,而修正最大周向应力断裂判据预测结果和实验结果相吻合;当T应力为正并且超过某一定值时,裂纹的扩展路径将发生偏折;T应力对脆性材料断裂试件的断裂韧度和裂纹扩展路径有影响.     

激光散斑法对冻土微裂形貌和发展过程的研究

将激光散斑法用于冻土材料，得出了裂纹尖端存在一个微裂纹损伤区（或称为断裂过程区）的结论，通过对裂纹尖端一系列散斑图的逐点分析，绘出了微裂纹区随载荷增加而发展的形貌及其全过程。测定了裂纹嘴张开位移的临界值δｃ，从而为冻土材料的宏微观力学行为研究及弹塑性断裂韧度测试分析提供了有效的途径。     

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