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71.
对于水泥砂浆的抗弹性能研究,目前很少考虑靶体所处的应力状态,为此基于自研的真三轴静载混凝土侵彻实验装置和水泥砂浆抗弹性能实验结果,讨论了水泥砂浆在不同应力状态下的开坑深度和开坑阻力。应用侵彻深度的经验公式和基于HJC模型的有限元数值计算方法,对比分析了水泥砂浆侵彻实验,结果表明,对于低速冲击过程,采用UMIST公式和HJC模型的数值分析对开坑深度的预测较为有效。应力状态对开坑深度有明显的影响,即随着侧限增加,水泥砂浆的三轴强度提高,弹丸的开坑深度减小。应用基于HJC模型的数值分析方法,研究了弹丸开坑过程中弹体内的加速度波形和y轴支撑杆上的波形,结果表明:弹丸开坑过程对两种波形都有影响,其中y轴支撑杆上的波形可以更好地反映开坑过程。虽然数值模拟结果与实验波形的趋势基本一致,但是应力幅值有一定的差异,说明基于HJC模型的数值分析对开坑阻力的计算能力尚待提高。 相似文献
72.
In this paper we study the theoretical properties of multigrid algorithm for discretization of the Poisson equation in 2D using a mortar element method under the assumption that the triangulations on every subdomain are uniform. We prove the convergence of the W-cycle with a sufficiently large number of smoothing steps. The 相似文献
73.
This paper proposes a mortar finite element method for solvingthe two-dimensional second-order elliptic problem with jumpsin coefficients across the interface between two subregions.Non-matching finite element grids are allowed on the interface,so independent triangulations can be used in different subregions.Explicitly realizable mortar conditions are introduced to couplethe individual discretizations. The same optimal L2-norm andenergy-norm error estimates as for regular problems are achievedwhen the interface is of arbitrary shape but smooth, thoughthe regularity of the true solution is low in the whole physicaldomain. 相似文献
74.
水基聚合物在混凝土中的应用 总被引:4,自引:0,他引:4
随着人们对材料结构与性能关系的深入认识,越来越多的水基聚合物被广泛用于混凝土行业中。本文主要介绍了水基聚合物在混凝土外加剂,主要是混凝土减水剂、引气剂、增粘剂、减缩剂中的应用情况,以及在聚合物混凝土中的应用现状,以期引导更多的化学和材料工作者投入到混凝土材料的研究中来,促进砼技术的快速发展。 相似文献
75.
J. P. Gonçalves R. D. Toledo Filho E. M. R. Fairbairn 《Journal of Thermal Analysis and Calorimetry》2008,94(2):511-516
This paper reports an experimental study on the magnesium sulphate resistance of mortar specimens incorporating 0, 10 and
20% of metakaolin (MK). The evidence of the attack was evaluated through the content of calcium hydroxide (portlandite) and
formation of magnesium hydroxide (brucite) by thermal analysis (thermogravimetric and derivative thermogravimetric analysis).
The mechanical degradation of the mortar specimens was evaluated through splitting tensile tests after 200 days of exposition
to the magnesium solution. The addition of metakaolin resulted in a reduction in the content of calcium hydroxide and in a
smaller formation of brucite in comparison with reference mixture. A tensile strength loss of about 7% was observed for the
metakaolin mortars submitted to the magnesium solution attack for 200 days. 相似文献
76.
L. V. Maslovskaya O. M. Maslovskaya 《Computational Mathematics and Mathematical Physics》2009,49(4):657-671
Nitsche’s mortar method for matching grids in the Hermann-Miyoshi mixed scheme for the biharmonic equation is considered. A two-parameter mortar problem is constructed and analyzed. Existence and uniqueness theorems are proved under certain constraints on the parameters. The norm of the difference between the solutions to the mortar and original problems is estimated. The convergence rates are the same as in the Hermann-Miyoshi scheme on matching grids. 相似文献
77.
78.
Determination of carbonation profiles in non-hydraulic lime mortars using thermogravimetric analysis
The carbonation profile of material taken at various depths in a lime mortar specimen has been determined at different times from manufacture using a novel, high-speed thermogravimetric analysis (TGA) method. While conventional phenolphthalein staining suggests a sharp boundary between carbonated and non-carbonated regions, the new TGA technique shows that up to 15% (w/w) of portlandite remains uncarbonated at the exterior of the mortar and that the extent of carbonation declines linearly over up to 15 mm into the interior. The technique demonstrates the possibility of identifying the presence of Liesegang patterns by measuring variations in the concentration of Ca(OH)2 through the depth profile. 相似文献
79.
本文讨论了mortar型旋转Q_1元的多重网格方法.证明了W循环的多重网格法是最优的,即收敛率与网格尺寸及层数无关.同时给出了一种可变的V循环多重网格算法,得到了一个条件数一致有界的预条件子.最后,数值试验验证了我们的理论结果. 相似文献
80.
Under dynamic loading, the constitutive relation of the cement mortar will be significantly affected by the transversal inertial effect of specimens with large diameters. In this paper, one-dimensional theoretical analysis is carried out to determine the transversal inertial effect on the relaxation/retardation time of the cement mortar under the harmonic wave. Relaxation time or retardation time is obtained by means of the wave velocity, attenuation coefficient and the frequency of the harmonic wave. Thus, the transversal inertial effect on the relaxation time from Maxwell model, as well as on retardation time from Voigt model is analyzed. The results show that the transversal inertial effect may lead to the increase of the relaxation time, but induce the decrease of the retardation time. Those should be taken into account when eliminating the transversal inertial effect in applications. 相似文献