Results 11 to 20 of about 534,641 (114)
, 1982 某些作者给出的数值结果表明,在单元形状不规则时,八节点和十二节点的四边形等参数单元的刚度变硬。因此,应用不规则单元所得的结果误差很大。计算结果没有由二个或四个六节点三角形组成的四边形所得的结果妤。本文表明,假使四边形单元是九节点单元,拉格朗日多项式作为插值函数,那么不规则单元所得的结果与规则单元所得的结果基本上一致。数值结果表明,九节点等参数单元比八节点 ...
吴永礼
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, 1984 用有限元法计算应力强度因子的各种奇异元中,由八节点或十二节点的四边形等参数单元所派生的奇异元最为简单,因为这种单元就是原有的等参数单元,无须程序变动,只要适当地改变裂纹顶点单元的边中点的坐标,就可使应变具有γ~(-1/2)的奇异性。这种单元是协调单元,满足收敛准则,当有人提出过渡单元概念以后,使计算结果更为精确,因此,这种单元是工程中广泛应用的一种计算应力强度因子的奇异元。与四边形等参数单元相应的一族单元是自然三角形单元。下面证明六节点的二次三角形单元和十节点的三次三角形单元 ...
吴永礼
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, 2021 在圆钢管单层网壳结构中,圆钢管构件在壳体曲面内、外的计算长度不同,造成材料性能无法在两个方向上均得到充分利用。提出以H形钢为杆件形式的单层网壳结构克服了上述不足。首先通过一则算例对比分析了圆钢管和H形钢两种杆件形式在单层网壳曲面内、外的轴心受压稳定性差异,随后为进一步减小单层网壳中杆件弯矩对构件受力的影响,运用力密度法对H形钢单层网壳进行形态优化,并对比了找形前、后单层网壳的静力性能。研究结果表明,H形钢轴心受压稳定应力在壳体曲面内、外可以达到平衡且在曲面外低于同截面面积圆钢管的稳定应力 ...
张玉轩, 巩昊, 闫翔宇, 陈志华
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Effects of Hydrogen on Shear Bands and Cracking in Zr Base Bulk Amorphous Alloy
, 2006 通过充氢和未充氢缺口拉伸试样和三点弯曲试样在SEM下的原位加载,研究了氢对Zr65Al7.5Ni10Cu17．5块体非晶合金形变和开裂过程的影响．结果表明,无论是否有氢,块体非晶的剪切带发展到临界尺寸,剪切裂纹就沿剪切带形核、扩展,它一旦张开就导致快速的断裂．断口边缘观察到的无特征区是剪切带,而不是剪切裂纹断口;剪切断口形貌和拉伸断口形貌没有本质区别．只有当长时间充氢才能形成氢鼓泡,如鼓泡很小或尚未形成,则氢对剪切带以及裂纹的形核、扩展没有明显影响;如存在较大的氢鼓泡 ...
李金许 +4 more
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World Water Policy, Volume 12, Issue 4, November 2026.ABSTRACT This article examines how renewable‐energy expansion is changing water–energy bargaining among Iran, Iraq, and Türkiye in the Tigris–Euphrates basin. Much of the existing literature on transboundary water politics focuses on territorial control, upstream–downstream power asymmetries, legal rules, and hydro‐hegemony but gives less attention to ...
Umud Shokri
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, 2015 利用密度泛函理论系统地研究了单层黑磷的纯弯变形特性,揭示了单层黑磷沿锯齿型方向弯曲时的失稳现象,并与石墨烯和单层二硫化钼的弯曲变形行为进行了比较.在此基础上,从连续介质力学的角度引入等效原子面积,计算了3种材料的弯曲刚度,并且与实测值和经验势的结果很好地符合.结果表明,单层黑磷的弯曲变形体现了明显的各向异性,刚度过大的锯齿型弯曲是导致其失稳区过早出现的力学根源 ...
潘斗兴
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Rare Metals, Volume 45, Issue 10, October 2026.ABSTRACT To improve the strength–toughness balance of IN718, and alleviate the brittleness commonly associated with refractory high‐entropy alloys, this study proposes a novel strategy to fabricate defect‐free IN718/WMoTaNb heterogeneous multiprincipal element alloy coatings via laser‐directed energy deposition.
Zhao Wang +7 more
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Rare Metals, Volume 45, Issue 10, October 2026.ABSTRACT Systematic studies on the fatigue deformation and damage mechanisms of nickel‐based single‐crystal superalloys (Ni‐SXs) under combined thermal and mechanical conditions remain limited, particularly regarding the influence of strain amplitude on the relative contributions of fatigue and oxidation damage.
Liyin Zhang +7 more
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Rare Metals, Volume 45, Issue 10, October 2026.ABSTRACT Developing rapid, precise gas sensors for Listeria monocytogenes (LM) biomarker detection faces challenges due to suboptimal gas‐solid interactions. Herein, we report the rational synthesis of amino‐functionalized mesoporous SiO2 hollow nano‐doughnuts (MS‐2‐NH2‐2) via modification with (3‐aminopropyl) trimethoxysilane (AAPTMS), which enables ...
Xingyu Wang +7 more
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OnomázeinAlthough å§å§ /jiejie/ (“elder sister”) and 妹妹 /meimei/ (“younger sister”) are basic relatives' terms of the nuclear and consanguinity kinship, they mean a big challenge when they are translated into Spanish because of the linguistic and cultural differences and defaults between the Chinese and the Spanish.
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