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对薄层单元的基本假设和简化进行了探讨并得到如下结论：薄层单元的本构方程可 通过横观各向同性体本构方程采用合理简化得到;薄层单元受拉开裂的本构关系可 采用分布裂缝模型模拟开裂简化得到;薄层单元采用的基本假 设能在一定程度上保证计算精度及简化计算.     

基于区间参数摄动法的三维弹塑性区间有限元探讨

首次探讨了弹塑性问题的区间分析,推导了三维弹塑性问题的区间参数摄动法有限元计算公式,研制了相应的弹塑性区间有限元程序,通过算例分析得到结论:(1)采用增量法对弹塑性问题进行区间分析时,增量位移离差随着增量位移均值的增大而增大.(2)单元高斯点应力没有达到屈服极限之前,高斯点的应力离差很小;当单元高斯点应力达到屈服极限之后,高斯点应力离差逐渐增大.(3)是否考虑塑性矩阵的应力分量为弹塑性参数的隐函数,对应力高差计算的影响较小.     

氧化镁在不同养护条件下水化产物的形貌分析

The morphologies of brucite formed from MgO hydration under different curing conditions were studied. The results showed that there were relations between the morphologies of brucite and its forming conditions. The size of brucite crystals increased with the curing time, and they were fiber-shaped at lower curing temperature and stick-shaped at higher temperature. When MgO was cured in paste with 10 percent cement, the crystal of brucite was fiber-shaped, while cured in paste with 95 percent cement, the crystal was hexaflaggy-shaped, which aggregated and produced some micro-cracks in paste when the curing temperature was increased. At 180 ℃ autoclaving temperature of MgO, the brucite was regular hexaflaggy-shaped crystal; for 216 ℃, it was less irregular. When the paste mixed with 50 percent fly ash, the crystal of brucite was needle-shaped and distributed more evenly, so decreased the deformation and crack of the concrete.     

不同应力分量下广义开尔文模型粘性系数探讨

对不同应力分量下的广义开尔文模型应力应变关系进行了研究,推导了在不同应力分量下的广义开尔文模型的粘性应变增量计算式;通过对这些粘性应变增量计算式的比较分析,得到结论:对于线性粘弹性模型,当应力张量引起粘性变形的规律与应力偏量和球应力分别引起粘性变形的规律相同时,它们的系数满足关系式Ek/ηk=Gsk/ηsk=Kmk/ηmk;否则,这个关系式不成立.现有文献采用应力张量表示的粘性变形有限元计算式隐含假定了球应力与应力偏量产生的粘性变形规律相同.对于复杂的工程材料而言,这种假定并不总是合适的.这在工程问题粘性分析时值得注意.