混凝土施工中裂缝产生原因分析及防治

裂缝在施工中常见的为温度裂缝、收缩裂缝、沉陷裂缝等，依据混凝土特性及施工工艺方法加以防治的技术要求必须十分规范，施工操作必须严格。     

Invariant Integrals for the Equilibrium Problem for a Plate with a Crack

We consider the equilibrium problem for a plate with a crack. The equilibrium of a plate is described by the biharmonic equation. Stress free boundary conditions are given on the crack faces. We introduce a perturbation of the domain in order to obtain an invariant Cherepanov–Rice-type integral which gives the energy release rate upon the quasistatic growth of a crack. We obtain a formula for the derivative of the energy functional with respect to the perturbation parameter which is useful in forecasting the development of a crack (for example, in study of local stability of a crack). The derivative of the energy functional is representable as an invariant integral along a sufficiently smooth closed contour. We construct some invariant integrals for the particular perturbations of a domain: translation of the whole cut and local translation along the cut.     

用可动节点有限元模型模拟裂纹扩展过程

本文针对裂纹扩展有限元模拟模型存在的问题,提出一种可动节点模型.使裂尖在单元尺度内任意移动,实现了扩展模拟连续性.加进松弛扩展,突出其所占比重,使模拟更加逼真.用弹塑性有限变形杂交元自编模拟裂纹扩展的通用FORTRAN 程序,对含中心裂纹铝板进行模拟,假定材料各向同性并遵守等向强化规律,采用米赛斯屈服准则和Drucker 塑性势流动理论做增量弹塑性静力分析,得到了与实验符合较好的结果.     

基于X射线CT基础上的砂岩破裂模式研究

借助CT机对砂岩破裂过程的实时观测以及结合CT图像和CT数的分析发现：在单轴和三轴压力作用下，砂岩CT数方差变化剧烈的地方发生脆性变化，而方差比较稳定的地方发生塑性变化；当有渗透水流作用时，砂岩应变特性与干砂岩的应变特性有明显差异，峰值强度显著增大，残余强度也明显增加；砂岩在单轴干燥状态下发生脆性破坏，而在有渗透压力和围压的情况下发生塑性破坏。通过CT技术可以方便地计算出砂岩的实时孔隙率。     

半平面压电体的Green函数及其应用

本文研究半平面压电体在线力、电荷和位错作用下的弹性场和电场，即Green函数．基于各向异性弹性力学中的Stroh方法和解析延拓理论，推导了Green函数的封闭形式的解．作为解的应用，分析了含半无限裂纹的无限大压电介质的机电耦合场，给出了应力和电位移强度因子的解析表达式．     

Penny-shaped crack in a piezoelectric cylinder under electro-mechanical loads

Summary The fracture behavior of a penny-shaped crack in a axisymmetrical piezoelectric ceramic cylinder of finite radius under mechanical and electrical loads is analyzed under electric continuous boundary conditions on the crack surface. The potential theory and Hankel transform are used to obtain a system of dual integral equations, which is then expressed as a Fredholm integral equation. Singular mechanical and electrical fields and field intensity factors of mode I are obtained. The numerical values of various field intensity factors for PZT-6B piezoelectric ceramics are graphically shown for a uniform load and a ring-shaped load, respectively. The effects of the radius of the cylinder on the field intensity factors are investigated. This work was supported by the Korea Research Foundation Grant (KRF-2001-041-E00057).     

产业用纤维材料的耐候性和耐热性研究

本文对我国常用的几种产业用纤维材料的耐候性和热老化性能进行了测试分析。随着室外老化和仪器老化时间的增加,纤维材料强度和断裂伸长率降低;同时,纤维因受气候条件的侵蚀而表面下陷,出现斑点、凹坑和裂纹.仪器老化能较好地模拟室外自然老化试验,且数据稳定,试验周期短。两者的强度保持率随着老化时间均按指数规律 Y=ae~(bx)降低,试验常数 a 和 b 决定于纤维品种,规格和气候老化条件等参数。在经130℃热老化处理后,常用几种产业用纤维的强伸性能均发生不同程度的恶化;但在80℃条件下,性能变化较小。     

水玻璃结合不烧铝镁砖龟裂的分析探讨

根据实验室研究和工业试验,水玻璃结合不烧铝镁砖龟裂与水玻璃摸数、波美度、泥料颗粒组成、废砖反复加入量、干燥时间等因素有关。最佳工艺参数为n=2.45～2.65,B=47～50Be,泥料粒度应控制大于3mm和小于或等于0.088mm部分均占36％左右,干燥时间为16h,废砖不宜集中使用。     

反平面动态扩展裂纹问题的研究

应用复变函数论，对反平面动态扩展裂纹问题进行了研究。通过自相似函数的方法可以获得若干问题的解析解。应用该法可以迅速地将所论问题转化为Riemann-Hilbert问题，并可以相当简单地得到问题的闭合解。通过叠加原理利用这些解，就可以求得任意复杂问题的解。     

Fatigue crack propagation and related failure in modified,andhydride-cured epoxy resins

The fatigue crack propagation (FCP) of neat and modified, anhydridecured epoxy resin (EP) was studied in tensile-tensile mode at ambient temperature. As modifiers, liquid carboxyl-terminated acrylonitrile-butadiene (CTBN) and silicon rubber (SI) dispersions were used. The latter modifier in a defined particle size distribution was produced by a special latex technology, whereas the former developed in situ in the EP by phase separation during curing. The dispersion-type morphologies of the EPs were characterized by using polished sections and viewing them in a scanning electron microscope (SEM). The resulting frequency distribution curves were compared with those analyzed from fatigue fracture surfaces. Probable failure mechanisms were also studied by SEM-fractography.Both modifiers improved the resistance to FCP by shifting the curves to higher stress intensity factor ranges (K) in relation to the reference curve determined for the neat EP-matrix. The failure mechanisms, summarized also schematically, differed basically for the various modifiers. According to this, rubber-induced cavitation and shear yielding of the matrix seemed to be dominant for CTBN, which did not affect the principal crack plane. In contrast to this, crack bifurcation, branching and, hence, a forced deviation in the fatigue crack path induced by debonded SI-particles in the EP-matrix were concluded for the SI modifier. The common use of both modifiers yielded a positive synergistic effect due to the superposition of the above failure mechanisms.Dedicated to the 60th birthday of Prof. H. H. Kausch