运用仿真技术预测疲劳寿命

采用人工神经网络的方法描述了材料在疲劳损伤过程中的性能变化，并将材料的疲劳过程看作一个离散事件，建立了即能反映累积损伤的非线性效应，又能反映材料循环特性的疲劳损伤累积模型．通过将估算结果与实验值的比较，证明该方法有效地提高了寿命估算精度．     

非线性疲劳损伤累积理论研究

为解决两级载荷作用下的材料常在损伤值不为一时破坏的问题，在原有常用疲劳累积理论的基础上，避开等效损伤，并考虑加载顺序、领域潜在损伤和损伤的非线性对材料疲劳寿命的影响，建立了一种非线性疲劳损伤累积模型及其计算公式，并利用两种材料疲劳实验数据，通过该模型预测了它们疲劳寿命，所得结果符合实际，证明了该模型及其计算公式对材料进行寿命预测是可行的．     

一种混凝土材料损伤模型研究

建立一种混凝土材料损伤模型,并将该模型应用于混凝土材料的损伤分析;以连续损伤力学理率为基础,应用Ｊ．Ｌａｍａｉｔｒｅ的“应等效怀”假说,和“利帕托夫强度”理论作为破坏准则,对混凝土材料的Ｐｆｅｉｆｆｅｒ和Ｂａｚａｎｔ试件在直剪和压剪载荷作用下的损伤发展过程进行了数值模拟;与Ｓ．Ｅ．Ｓｗａｒｔｚ和Ｎ．Ｍ．Ｔａｈａ实验结果作了比较,二得较吻合;证明该损伤模型可以用于混凝土材料的抽伤分析研究。     

测定临界破坏损伤变量的扭转实验法

在Ｌｅｍ ａｉｔｒｅ 损伤演变规律基础上,对各向同性硬化材料临界破坏损伤变量进行了研究。利用材料扭转实验的最大扭矩,结合材料单向拉伸的损伤起始应变门槛值与临界破坏应变的比值,推得测定该材料临界破坏损伤变量的扭转实验的一般测定公式．     

煤岩力电耦合模型及其参数计算

电磁辐射技术已经在矿山煤岩动力灾害预报中得到了应用，根据煤岩强度的统计理论和损伤力学理论，建立了受载煤岩的力电耦合模型，推导得到了该模型中参数的确定方法，并结合实验结果对其中的参数进行了计算．结果表明：煤岩材料的破坏是内部代表性体元微损伤累积的结果，电磁辐射可以反映煤岩体的损伤程度，力电耦合模型能够较好地描述煤岩变形破裂过程的电磁辐射规律，参数的拟合相关系数较大说明该方法合理可行．     

非线性损伤材料中Ⅲ型裂纹尖端场

为了研究损伤对裂纹尖端场的影响，在Krajcinovic一维脆性材料损伤模型的基础上，从宏观的唯象角度出发，采用连续损伤力学中的热力学内变量理论，推导出三维空间非线性损伤材料的本构方程，建立了一种非线性应变损伤模型，得出非线性损伤材料皿型裂纹尖端应力、应变和损伤场的解析表达式及其数值计算结果．经过分析得出损伤指数n和损伤变量D对裂尖场的影响较大，应力、应变为有限值，不具有奇异性，从而在理论上解释了实际材料在有限应力下破坏的现象，与工程实际相符．     

用非线性塑性模型标定LY12-CZ薄板的损伤参数

重点研究了薄板材料的非线性Lemaiter—Chaboche塑性损伤模型参数的测试与标定方法．首先，利用大圆弧变截面拉伸试样检测不同塑性损伤状态下材料弹性模量的变化，进而换算得到材料单轴塑性损伤演化曲线，即ω（E）-εP曲线；然后，参照Lemaiter—Chaboche塑性损伤模型中的非线性塑性损伤演化方程，拟定一个相关三参数幂指数函数作为目标函数，并采用了数值迭代-拟合方法确定拟合参数；最后标定出了材料的非线性塑性损伤模型参数．文中还就LY12-CZ薄板材料的损伤与破坏行为进行了实验测试与分析．     

InGaN太阳能电池材料电学与光学性质的辐射研究

研究表明，In1-xGaxN合金材料的能隙能连续地从0．7eV改变到3．4eV，使得该材料有可能成为太阳能全光谱材料系．研究发现这些合金材料的电学特性表现出用高能质子（2MeV）照射比当前常用的太阳能光伏材料如GaAs和CaInP有更高的电阻，因此，给受到强辐射的太阳能电池提供了巨大的应用潜力．实验观察到这种材料对辐照损伤具有不敏感的特征，该特征可用带边局域的平均振荡结合缺陷能给予解释．该缺陷能用In1-xGaxN合金的Fermi能级的稳态能描述．     

材料工业的环境成本评估体系探索

通过分析材料产业的环境形势和推广材料环境协调性技术所碰到的问题，主张利用经济手段促使有益于环境的技术变成市场需求．针对材料产业的环境问题，剖析了生命周期评价环境损伤计量功能，论证了生命周期评价损伤计量功能对环境损伤计价的支持能力．提出应建立可操作的地区环境损伤计价方法，建立相关标准规则将环境损失转化为货币价值形式纳入会计系统，并构建绿色税制的思路．     

混凝土材料损伤的数值模拟

本文采用各向同性损伤模型，利用有限单元法对混凝土材料损伤破坏发展过程进行了数值模拟，着重分析了裂缝尖端及附近，试件中心的应力、位移、损伤值的发展变化，力图掌握其损伤发展及裂纹萌生的规律及其产生的相关力学因素、数值计算结果与Ｓ．Ｅ．ＳＷＡＲＴＺ和Ｎ．Ｍ．ＴＡＨＡ的实验结果作了比较，二者比较吻合，初步表明了各向同性损伤模型的有效性和有限元法在研究脆性材料损伤破坏这一领域的实用性。     

基于轴向振型差变化率的空间刚架结构损伤研究

通过结构动态特性参数对损伤位置和损伤程度的敏感性分析,提出以轴向振型差变化率为标示量的空间刚架损伤识别方法。应用ANSYS建立了空间刚架结构无损伤和有损伤的有限元模型,选取轴向振型差变化率作为损伤标示量进行结构损伤识别。结果表明：一阶轴向振型差变化率不但能很好地对单一或多个损伤的损伤位置进行识别,而且可以初步识别损伤程度。将此方法应用到实验刚架模型中,实现了对刚架损伤位置的识别。轴向振型差变化率具有敏感性高、回避空间振动方向性、减少工作量等优点,是一种较理想的空间刚架损伤标示量。     

高重频皮秒脉冲激光对多晶硅的损伤特性研究

为研究高重频皮秒脉冲激光对多晶硅的损伤特性,用不同重复频率的皮秒脉冲激光辐照多晶硅,用扫描电子显微镜对激光辐照后多晶硅的损伤形貌进行检测。探究了高重频皮秒脉冲激光与多晶硅相互作用的机理,得到了不同辐照时间和重频的皮秒激光对多晶硅的损伤规律。研究表明:多晶硅的损伤阈值随着皮秒激光重频的增加逐渐降低,当激光重频大于5k Hz时,多晶硅的损伤阈值达到一个"饱和"值,损伤阈值几乎不再随着重频的增加而发生变化。研究结果对低脉冲能量高重复频率激光加工具有借鉴意义。     

基于三向振型变化率的空间刚架结构损伤识别

选取振型变化率作为标示量,对空间刚架进行结构损伤识别。应用ANSYS建立了空间刚架结构无损伤和有损伤的有限元模型,对空间刚架空间三向振型变化率进行计算。分析结果表明：一阶振型变化率能很好地对损伤位置进行识别,也能根据一阶振型变化率对损伤程度进行初步判断,为探索通过振型变化率识别空间刚架的结构损伤提供了一种可行的方法。     

考虑空穴多级形核的损伤材料内时本构关系

本文提出了多级形核的损伤模型,建立了无形核损伤变量与无形核损伤能释放率、形核损伤变量与形核损伤能释放率之间的损伤发展的内蕴时间演变关系。     

Damage evolution and dynamic response of cement asphalt mortar layer of slab track under vehicle dynamic load

The damage evolution and dynamic performance of a cement asphalt (CA) mortar layer of slab track subjected to vehicle dynamic load is investigated in this paper. Initially, a statistical damage constitutive model for the CA mortar layer is developed using continuous damage mechanics and probability theory. In this model, the strength of the CA mortar elements is treated as a random variable, which follows the Weibull distribution. The inclusion of strain rate dependence affords considering its influence on the damage development and the transition between viscosity and elasticity. Comparisons with experimental data support the reliability of the model. A three-dimensional finite element (FE) model of a slab track is then created with the commercial software ABAQUS, where the devised model for the CA mortar is implemented as a user-defined material subroutine. Finally, a vertical vehicle model is coupled with the FE model of the slab track, through the wheel-rail contact forces, based on the nonlinear Hertzian contact theory. The evolution of the damage and of the dynamic performance of the CA mortar layer with various initial damage is investigated under the train and track interaction. The analysis indicates that the proposed model is capable of predicting the damage evolution of the CA mortar layer exposed to vehicle dynamic load. The dynamic compressive strain, the strain rate, and the induced damage increase significantly with an increase in the initial damage, whereas the dynamic compressive stress exhibits a sharp decrease with the increasing initial damage. Also, it is found that the strain rate dependence significantly influences the damage evolution and the dynamic behavior of the CA mortar layer.     

Dynamic Mechanical Characteristics and Damage Evolution Model of Granite

By using the technique of the split Hopkinson pressure bar (SHPB),impact tests at different stress wavelengths(0.8-2.0 m) and strain rates (20-120 s-1) were conducted to study the dynamic mechanical properties and damage accumulation evolution law of granite.Test results show that the dynamic compressive strength and strain rate of granite have a significantly exponential correlation;the relationship between peak strain and strain rate is approximately linear,and the increase of wavelengths generally makes the level of peak strain uplift.The multiple-impacts test at a low strain rate indicates that at the same wavelength,the cumulative damage of granite shows an exponential increasing form with the increase of strain rate;when keeping the increase of strain rate constant and increasing the stress wavelength,the damage accumulation effect of granite is intensified and still shows an exponential increasing form;under the effect of multiple impacts,the damage development trend of granite is similar overall,but the increase rate is accelerating.Therefore the damage evolution model was established on the basis of the exponential function while the physical meaning of parameters in the model was determined.The model can reflect the effect of the wave parameters and multiple impacts.The validity of the model and the physical meaning of the parameters were verified by the test,which further offer a reference for correlational research and engineering application for the granite.     

Water absorption and chloride ion penetrability of concrete damaged by freeze-thawing and loading

In order to investigate water and chloride ion transport in damaged concrete, three types of concrete were prepared, freeze-thawing (F-T) cycling and compressive loading were adopted to induce damage to concrete. Ultrasonic pulse velocity technique was used for evaluating the damage degree of concrete, and the defects of damaged concrete were also detected by X-CT. Water absorption and chloride ion penetrability were used for describing the transport properties of damaged concrete. Effects of damage degree on the water absorption rate and chloride ion penetrability were investigated in detail and the relationships were also established. The results show that the water absorption of concrete makes various responses to damage degree due to the difference of concrete type and damage method. For same concrete with similar damage degree, the water absorption rate of F-T damaged concrete is usually larger than that of concrete damaged by loading. The chloride ion penetrability of damaged concrete increases linearly with increasing damage degree, which is more sensitive to damage degree if the original penetrability of sound concrete is higher.     

不同倾角节理岩体损伤演化特征分析

为研究节理倾角对岩体损伤的影响规律,运用损伤力学理论建立考虑节理与荷载共同作用的岩体损伤演化模型及损伤本构模型;通过单弱面理论对模型试验进行验证,同时探讨节理岩体损伤演化特征.结果表明:单弱面理论结果与试验结果较为吻合,模型试验能较好地表征含单一结构面的岩体在荷载作用下的力学特征及损伤演化规律;当节理倾角从0增大到90°过程中,初始节理损伤先增后减,在倾角为60°时至最大值,总体呈倒"U"型分布规律;不同倾角节理岩体总损伤演化规律基本一致,均呈"S"型分布规律,先缓慢增加,而后快速增加,最后再缓慢增加其值趋于1;节理倾角只影响总损伤率数值大小不影响其演化规律,总损伤率随应变增加呈正态分布;总损伤率受控于节理面分布规律,当节理倾角从0增大至90°的过程中,总损伤率先减小后增大.     

易漏盐岩地层固井多功能水泥浆体系研究及应用

中原油田易漏盐岩地层油井的套损现象呈增长趋势。分析套损原因认为，固井过程中的水泥浆低返、高脆性水泥环的射孔破裂和水泥石变形能力差与之有关。采用以F27A防漏增韧剂为主的多功能水泥浆体系有望解决易漏盐岩地层固井作业中相关技术难题。室内研究和模拟射孔试验表明：该体系具有防漏、增韧、低滤失和零析水特性，水泥浆的其它工程性能也满足施工的技术要求，5个不同区块12口井的固井优质率达到66．7％。多功能水泥浆体系的应用，将有助于降低射孔段和盐岩段的套损率。