酚醛树脂-CarboresP结合镁碳材料的性能与应用

研究了环境友好型含碳材料CarboresP在镁碳砖中的应用。采用MT14A镁碳砖生产工艺,改变CarboresP的加入量,对试样180℃处理后的体积密度、高温抗折强度(1400℃),以及1000℃埋炭处理后的显气孔率、耐压强度等指标进行了研究和对比,确定镁碳砖中合适的CarboresP添加量为1%,并且可适量降低金属防氧化剂的加入量;分析了酚醛树脂-CarboresP结合炭的显微结构,表明其为均质炭和非均质石墨化炭的混合结构,这将有助于改善炭化结构的抗氧化性能;采用尖劈试验绘制镁碳砖试样的应力-应变曲线,表明添加CarboresP的镁碳砖的特征长度LCH值得到明显提高,说明它具有很好的韧性和吸收应力的能力;与传统工艺生产的MT14A镁碳砖相比较,采用酚醛树脂-CarboresP“软性结合”工艺生产的MT14A镁碳砖,成型性能及热处理后各项性能指标均得到改善,在国内某40tLF-VD精炼钢包渣线上进行现场使用证明,平均使用寿命比现用渣线镁碳砖提高18.4%。     

聚丙烯腈纤维在水浴牵伸过程中应力-应变曲线的研究

主要考察了聚丙烯腈纤维在水浴牵伸过程中的应力—应变曲线，以及温度、牵伸速率、水分对应力—应变曲线的影响。结果表明：聚丙烯腈纤维在水温为室温(26℃)、30℃～70℃时属于细颈牵伸，在80℃、90℃时是类橡胶牵伸，当水温低于60℃和牵伸速率太快时纤维易产生毛丝。所以在牵伸过程中，水温不能低于60％，牵伸速率要适中，在本实验条件下，200mm／min、500mm／min比较合适，而且在水中牵伸比在空气中牵伸效果好，可获得较大的牵伸率。     

Analysis of non-localized creep induced strains and stresses in notches

A method for the estimation of time-dependent strains and stresses induced in notches has been developed. The aim of the method is to generate a solution for the creep strain and stress at the notch root based on the linear-elastic stress state, the constitutive law, and the material creep model. The proposed solution is an extension of Neuber’s total strain energy density rule for the case of time-independent deformation. The method was derived for both localized and non-localized creep in a notched body. Predictions were compared with finite element data and good agreement was obtained for various geometrical and material configurations in plane stress conditions.     

Compressive stress-strain model for low-calcium fly ash-based geopolymer and heat-cured Portland cement concrete

This research focuses on elucidating the present knowledge gaps in geopolymer concrete's engineering properties, specifically its stress-strain behaviour. Geopolymer concrete (GPC) is an emerging alternative to ordinary Portland cement concrete (OPCC), and is produced via a polycondensation reaction between aluminosilicate source materials and an alkaline solution. As a relatively new material, many engineering properties of geopolymer concrete are still undetermined. In this paper, the compressive strength, modulus of elasticity and stress-strain behaviour of ambient and heat-cured GPC and OPCC have been studied experimentally. A total of 195 geopolymer concrete cylinders and 210 Portland cement concrete cylinders were tested for the above mentioned characteristics. Based on the experimental results, constitutive models describing the complete stress–strain behaviour in uniaxial compression have been developed for the low-calcium fly ash-based geopolymer concrete and the heat-cured Portland cement concrete.     

Extracting compressive stress-strain curve based on stick-slip shear banding process in bulk metallic glasses

Based on the stick-slip process, an effective method to extract the stress-strain curve directly from the crosshead displacement-load raw data in compression of bulk metallic glasses was proposed.The method was tested in two bulk metallic glass samples with different plasticities and shear band morphologies.The extracted stress-strain curves were found to well resemble the stress-strain curve measured by a laser ex-tensometer.In addition, the extracted curve could resolve fine structures of serrated flow much better than that measured by extensometer, thus facilitating the study of shear banding process.Results obtained by this method made the stick-slip dynamics of shear banding valid, and this method could be employed to obtain the real strain of small-sized metallic glass samples where extensometer cannot be applied.     

节理岩体加载实验的计算机模拟

本文介绍了在节理岩体结构模型的基础上，运用有限元方法在计算机上模拟了节理岩体的三轴加载实验，计算出节理岩体的应力应变曲线，为进一步确定节理岩体的力学参数提供了基础。     

Mathematical Modeling of the Stress-Strain State in Rock and Artificial Masses During Slice Chamber Mining of Underpit Reserves in the “Internatsionalnaya” Kimberlite Pipe

The statement and solution algorithm are proposed for the problem on the stress-strain state of a kimberlite body, filling massif, and enclosing rock during slice chamber mining with filling. The equations of nonlinear hereditary viscoelasticity are used as the constitutive relations for saliferous rocks. __________ Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 3, pp. 26–37, May–June, 2005.     

砂岩单轴三轴压缩试验研究

研究了砂岩在饱和、自然、风干三种状态下的单轴抗压强度特性和三轴抗压强度特性。在单轴、三轴压缩试验中得到了应力与纵向应变、横向应变、体应变之间的关系曲线，单轴应力一纵向应变曲线在峰值前可分为3个阶段，三轴应力一纵向应变全过程曲线可分为4个阶段。根据三轴轴向应力和围压绘制丁莫尔圆，采用回归分析得到了强度准则和强度参数C、Φ值，并且分析了含水量对岩石强度的影响，其实验结果能为工程提供参考与借鉴。     

岩石变形和破裂的损伤模型

利用损伤力学的基本观点,以岩石中缺陷呈泊松分布,分析了岩石应力—应变全过程曲线的形成所得到的方程式,可以较好地描述全过程曲线,所需参数也容易实际测出。     

矿岩料层动态粉碎应力－应变曲线的应变率效应分析

用自行研制的矿岩料层动态粉碎性能测试装置，对四种典型矿岩在五种不同应变率下进行实验研究，分析了应变率对应力－应变全过程曲线的影响。结果表明，应变率和应力－应变曲线相敏感，而且应变率效应随岩石物理力学性质和应力－应变曲线的不同发展阶段而改变。不同应变率下的岩石料层动态塑性特性可用Ｃｒｉｓｔｅｓｃｕ提出的拟线性塑性本构方程来描述。