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排序方式: 共有1233条查询结果,搜索用时 15 毫秒
1.
Mariia Svyntkivska Tomasz Makowski Ewa Piorkowska Marek Brzezinski Agata Herc Anna Kowalewska 《Molecules (Basel, Switzerland)》2021,26(5)
Electrospun nonwovens of poly(L-lactide) (PLLA) modified with multiwall carbon nanotubes (MWCNT) and linear ladder-like poly(silsesquioxane) with methoxycarbonyl side groups (LPSQ-COOMe) were obtained. MWCNT and LPSQ-COOMe were added to the polymer solution before the electrospinning. In addition, nonwovens of PLLA grafted to modified MWCNT were electrospun. All modified nonwovens exhibited higher tensile strength than the neat PLA nonwoven. The addition of 10 wt.% of LPSQ-COOMe and 0.1 wt.% of MWCNT to PLLA increased the tensile strength of the nonwovens 2.4 times, improving also the elongation at the maximum stress. 相似文献
2.
混凝土动态劈裂拉伸试验的数值模拟 总被引:4,自引:0,他引:4
采用LS-DYNA有限元编码程序,对混凝土的动态劈裂拉伸试验进行了数值模拟,给出了混凝土试样在不同类型加载情况下应力分布之间的差异,证实了动态劈裂拉伸试验的有效性,提出了改进试验方法的若干结论. 相似文献
3.
Statistical Analysis of the Effect of Mineral Admixtures on the Strength of the Interfacial Transition Zone 总被引:1,自引:0,他引:1
Microscopic evidence indicates that the thickness of the interfacial transition zone (ITZ) between the aggregate and the cement paste is modified when mineral admixtures partially replace portland cement. Unfortunately, there is limited information on the significance of these microscopic modifications to the mechanical properties of the ITZ. This research reports experimental results on the shear and tensile strength of the ITZ as affected by the addition of the following mineral admixtures: silica fume, fly ash, and natural pozzolan. Statistical analysis was used to identify the significant parameters affecting the tensile and shear strength of the ITZ. Experimental results indicate that not only does the incorporation of silica fume and fly ash increase the strength of the ITZ, these mineral admixtures have a greater influence on the strength increase of the ITZ than in the strength increase of the cement paste. 相似文献
4.
由于混凝土材料理化特性的差异,高强混凝土的弯压极限应变明显地小于普通混凝土,依据试验结果分析了高强混凝土的弯压极限应变变化规律,并给出了它的计算公式. 相似文献
5.
P.-A. Eriksson A.-C. Albertsson K. Eriksson J.-A.E. Månson 《Journal of Thermal Analysis and Calorimetry》1998,53(1):19-26
The thermal stability of heat-stabilised polyamide 66 in an oxidative environment is evaluated by DSC. The oxidative stability
of the polyamide decreases as a result of repeated injection moulding. The results also indicate that the presence of glass
fibres in the polyamide has a negative influence on the oxidative stability. Both isothermal and dynamic DSC measurements
seem to be useful tools for assessing the stability of polyamides and there is a relationship between data determined using
both procedures.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
6.
由于Cl^-过量引起混凝土钢筋锈蚀而过早的破坏,已成为世界性问题。混凝土外加剂中微量Cl^-是一个重要指标,准确测定氯离子的含量直接关系到混凝土配比的确定及浇灌后的质量。部颁及行业标准中是采用电化学滴定法和蒸馏法来测定混凝土外加剂的微量Cl^-[1,2],电化学滴定法对测定干扰大。本文采用电感耦合等离子体原子发射光谱法间接测定与微量Cl^-定量反应后剩余的Ag^ 含量,从而换算出Cl^-的含量,经回收验证及比较,证明本法简便、灵敏、快速,切实可行。 相似文献
7.
Calorimetry has been used in the investigations of calcium aluminate materials produced as a binder for aluminate-corundum
composites of high refractoriness. The kinetics and of hydration process was thus characterized and the optimum compositions
of initial binders and cement-corundum refractory filler blends could be selected for further tests. The acceleration of heat
evolution - the shortening of so-called induction period and relatively high heat output in the presence of corundum was observed.
It means the acceleration of hydration process, that is early crystallisation of hydration products and subsequent further
dissolution of initial anhydrous aluminate phases. In the presence of fine grained corundum particles these phenomena should
be attributed to the nucleating effect of fine corundum particles.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
8.
Lamination Design Optimization for Continuous Fiber Reinforced Composites of Variable Thicknesses北大核心CSCD 下载免费PDF全文
由于具备高的比强度、比刚度,利用连续纤维增强复合材料代替传统金属材料以实现结构轻量化正受到设计者们的广泛关注。然而,结构的复杂性给复合材料的铺层设计与优化带来了很大的挑战。针对航空用复合材料铺层设计约束多的问题,通过逐步构建设计变量准确表达结构的铺层信息。基于经典遗传算法框架,结合各设计变量特点,定义了铺层优化算法中的遗传算子,通过引入“修复”策略保证了每一代解都能满足设计约束,分布在可行域区间内。最后利用精英保留策略提高了算法的局部寻优能力,可以降低复杂复合材料结构铺层设计的计算成本。通过解决经典benchmark问题并与已有优化结果的比较,验证了前述铺层优化算法的全局、局部寻优能力,为工程实际中的复合材料铺层设计优化提供了理论支撑。 相似文献
9.
10.