Ni－Ti合金中基体柱状晶的取向分布规律

柱状晶的生长都具有一定的取向,形状记忆效应与柱状晶的生长取向有着非常直接的关系。我们利用Ｘ射线衍射仪可测出Ｎｉ－Ｔｉ合金柱状晶生长取向「１００」Ｂ２随着衍射角θ＾′的变化规律,从而对利用和推广形状记忆合金有着极为现实的意义。     

脉冲偏压对铝合金上TiN膜生长的影响

为了研究在铝合金上硬质膜的性能,促进硬质TiN膜在铝合金构件上的应用,利用电弧离子镀在7075铝合金上沉积TiN膜层,并通过改变脉冲偏压幅值研究其对薄膜生长过程的影响.结果表明,生长的TiN膜具有柱状特征,在无偏压或低偏压时,柱状特征明显,但随着负偏压值的增大,柱状特征变得不明显,膜层中Ti和N的原子比率增加,由无偏压、低偏压时近似为1.0增加到-200V偏压时的1.2.在0～-200V偏压范围内,沉积膜的平均生长速率由1.5μm/h增加到11.3μm/h.随着负偏压的增加,TiN膜的(111)方向的择优取向越来越明显,而(200)方向强度越来越小.沉积膜呈柱状生长,具有明显的择优取向,其程度受脉冲偏压影响.     

叠层橡胶支座竖向刚度退化对隔震结构的影响

隔震结构在地震作用下,叠层橡胶支座竖向刚度随剪切变形增加而不断退化,对整体隔震结构产生的影响尚不明确.为此,通过ABAQUS建立不同层数、层高、柱距的隔震框架结构,支座本构采用修正的双弹簧模型结果.通过ABAQUS用户单元子程序UEL,采用FORTRAN语言编写了能够考虑支座竖向刚度退化的支座单元程序;输入实际罕遇地震波,对结构进行弹塑性动力时程分析,研究支座竖向刚度退化对结构地震响应的影响.结果表明:支座竖向刚度退化对结构柱底剪力、轴力、弯矩及梁弯矩有一定影响,地震响应放大系数结果为1.1～1.3;支座竖向刚度退化对支座剪切变形及上部结构层间位移影响较小.研究结果可为今后进行罕遇地震作用下隔震结构的计算分析提供重要依据.     

晶析法除BF4-的研究

在氟硼酸废水治理研究中,探讨了常规钾盐沉淀法从低质量浓度BF4-废水中回收BF4-的可行性,在常规钾盐沉淀法回收BF4-条件研究基础之上,提出采用晶析法回收废水中的BF4-,使BF4-回收率>73%(绝对回收率理论值为76.9%).研究了晶种加入量、反应时间、pH等对BF4-回收率的影响,解决了KBF4分离难的问题.     

球型容器接管外拐角表面裂纹疲劳形状扩展数值计算方法

运用新型计算机数值计算方法对球型容器接管外拐角表面裂纹疲劳扩展形状和特性作了模拟跟踪研究 ,并与实验进行了比较 .结果表明接管外拐角表面裂纹的疲劳扩展同内拐角有一定的差异 ,并指出常规假定裂纹形状方法中的不足之处     

The hot compressive deformation behavior of the metal matrix composites with the large whisker orientation

Metal matrix composites are often subjected to ahot compressive plastic forming.During the thermome-chanical process the reinforcements are misaligned fromthe loading axis and rotate toward a more stable posi-tion.Meanwhile,the strain softening can be observedduring the hot compression of the metal matrix compos-ites reinforced with discontinuous reinforcements suchas the randomly oriented whiskers[1-3],the whiskersparallel to the applied loading[4-5]and the whiskerstilted away from the applie…     

Finite element simulation of influences of grain interaction on rolling textures of fcc metals

1INTRODUCTIONCrystallographic texture is an i mportant pa-rameter that describes the properties of materials,which can be developed at various stages in ther-mo-mechanical processing of polycrystalline met-als.Manyinvestigations have been done about thetexture prediction of polycrystalline materials ac-cording to the deformation conditions.The classi-cal si mulation of the deformation textures of poly-crystals may be mainly classified into Sachs andTaylor type models.A lot of researches …     

Modeling uniaxial tensile deformation of polycrystalline AI using CPFEM

The crystal plasticity finite element modeling （CPFEM） is realized in commercial finite element code ABAQUS with UMAT subroutine on the basis of the crystal plasticity theory of rate dependent polycrystal constitutive relations in the mesoscopic scale. The initial orientations obtained by electron backscatter diffraction （EBSD） are directly input into the CPFEM to simulate the mechanical response of polycrystalline 1050 pure Al in uniaxial tensile deformation. Two polycrystal models and two tensile strain rates were used in the simulations. The stress-strain curves of tensile deformation were analyzed. The predictions and the corresponding experiment result show reasonable agreement and slight deviation with experiments. The flow true stress of strain rate 0.01 s^-1 is higher than that of strain rate 0.001 s^-1. At the strain less than 0.05, the stress saturated rate of the experiment is higher than the simulated results. However, the stress saturated rate of the experiment becomes gentler than the corresponding simulated predictions at the strain over 0.05. Also, necking was simulated by the two models, but the necking strain is not well predicted. Tensile textures at strain 0.25 were predicted at the low strain rate of 0.001 s^-1. The predictions are in good accord with the experimental results. 2008 University of Science and Technology Beijing. All rights reserved.     

Modeling uniaxial tensile deformation of polycrystalline Al using CPFEM

The crystal plasticity finite element modeling (CPFEM) is realized in commercial finite element code ABAQUS with UMAT subroutine on the basis of the crystal plasticity theory of rate dependent polycrystal constitutive relations in the mesosocpic scale. The initial orientations obtained by electron backscatter diffraction (EBSD) are directly input into the CPFEM to simulate the mechanical response of polycrystalline 1050 pure AI in uniaxial tensile deformation. Two polycrystal models and two tensile strain rates were used in the simulations. The stress-swain curves of tensile deformation were analyzed. The predictions and the corre-sponding experiment result show reasonable agreement and slight deviation with experiments. The flow true stress of strain rate 0.01 s-1 is higher than that of strain rate 0.001 s-1. At the strain less than 0.05, the stress saturated rate of the experiment is higher than the simulated results. However, the stress saturated rate of the experiment becomes gentler than the corresponding simulated predictions at the strain over 0.05. Also, necking was simulated by the two models, but the necking strain is not well predicted. Tensile textures at swain 0.25 were predicted at the low strain rate of 0.001 s-1. The predictions are in good accord with the experimental results.     

裂纹对悬臂梁力学响应影响的扩展有限元模拟

扩展有限元继承了传统有限元的优点,在求解以裂纹扩展等为代表的一类不连续力学问题时具有明显的优势.主要探讨了含裂纹单元的积分域剖分,应用Fortran语言开发了相应的程序代码.以悬臂梁结构为例探讨了裂纹以及裂纹扩展对其力学响应的影响,数值结果表明了程序开发的正确性.     

Influence of substrate metals on the crystal growth of AlN films

AlN films were deposited by reactive radio frequency (RF) sputtering on various bottom electrodes,such as Al,Ti,Mo,Au/Ti,and Pt/Ti.The effects of substrate metals on the orientation of AlN thin films were investigated.The results of X-ray diffraction,atomic force microscopy,and field emission scanning electron microscopy show that the orientation of AlN films depends on the kinds of substrate metals evidently.The differences of AlN films deposited on various metal electrodes are attributed to the difference...     

化学计量比和铜离子对Fe:LiNbO3晶体光学性能的影响

以K2O作助溶剂,采用顶部籽晶溶液生长法生长近化学计量比Cu:Fe:LiNbO3晶体.测试了晶体的红外光谱,吸收光谱和抗光损伤能力.由红外光谱OH-吸收峰位置,确定Cu:Fe:LiN-bO3晶体是近化学计量比.吸收光谱显示出Cu:Fe:LiNbO3晶体的吸收边相对LiNbO3晶体发生红移.其抗光损伤能力比Fe:LiNbO3晶体提高一个数量级.对红外光谱OH-吸收峰移动机理,吸收光谱吸收边移动机理和抗光损伤增强机理进行讨论.通过二波耦合光路测试并计算了近化学计量比Cu:Fe:LiNbO3晶体的衍射效率、响应时间、擦除时间、灵敏度和动态范围.近化学计量比掺杂LiN-bO3晶体的光学性能优于Fe:LiNbO3晶体.     

Influence of substrate metals on the crystal growth of AIN films

AIN films were deposited by reactive radio frequency (RF) sputtering on various bottom electrodes, such as Al, Ti, Mo, Au/Ti, and Pt/Ti. The effects of substrate metals on the orientation of A1N thin films were investigated. The results of X-ray diffraction, atomic force microscopy, and field emission scanning electron microscopy show that the orientation of A1N films depends on the kinds of substrate metals evidently. The differences of A1N films deposited on various metal electrodes are attributed to the differences in lattice mismatch and thermal expansion coefficient between the A1N material and substrate metals. The A1N film deposited on the Pt/Ti electrode reveals highly the c-axis orientation with well-textured columnar structure. The positive role of the Pt/Ti electrode in achieving the high-quality A1N films and high-performance film bulk acoustic resonator (FBAR) may be attributed to the smaller lattice mismatch as well as the similarity of thermal expansion coefficient between the deposited A1N material and the Pt/Ti electrode substrate.     

Effect of interface kinetics on the eutectic growth

Eutectic alloy is widely used as structural and/or functional materials. The first mathematical model for the eutectic growth was established by Jackson and Hunt (JH)[1]. Assuming that crystals grow at low velocities, the lamellar spacing is much smaller than the solute diffusion distance, and the liquid composition at the solid-liquid interface is approximately the same as the equilibrium eutectic composition. They gave a relation- ship between the undercooling at the interface ?T and the e…     

N~ 注入Ag薄膜晶体生长机制的研究

采用离子注入方法在两种取向不同的 Na Cl衬底上制备 Ag单晶薄膜 ,研究离子注入引起晶粒长大、形成单晶体的过程 ,探讨离子注入 Ag薄膜晶体生长的机制     

光子晶体光纤的色散特性分析

利用矢量有限元法对零色散点在825nm的大空气孔光子晶体光纤进行模拟计算，在考虑石英基质的材料色散前提下，得到光纤的色散曲线．与实验数据对比，证明该计算方法的准确．同时调节光纤包层的空气孔分布及其占空比，得到不同光纤的色散特性曲线，发现增大包层空气孔直径或空气孔占空比可以使零色散点向短波长方向移动，通过改变包层空气孔分布可灵活设计色散位移光纤．     

非对称岩体削弱工程对矿体崩落影响的研究

本文根据国内某矿情况确定了岩体的力学参数与载荷条件,选用三维弹性有限元研究了非对称岩体削弱工程对矿体崩落进程的影响,提出了矿体的破坏机理和判据,以及合理布置岩体削弱工程的一系列原则。     

钢筋混凝土非线性有限元单元疏密对计算结果的影响

利用非线性有限元方法，对钢筋混凝土构件进行计算时，单元划分是必不可少的工作。本文通过对矩形截面钢筋混凝土受弯构件单元疏密的研究，分析了疏密度Ｃ对计算结果的影响。     

Influence of original microstructure on the transformation behavior and mechanical properties of ultra-high-strength TRIP-aided steel

The transformation behavior and tensile properties of an ultra-high-strength transformation-induced plasticity (TRIP) steel (0.2C–2.0Si–1.8Mn) were investigated by different heat treatments for automob...     

球面加载法在舰船舱室爆炸破坏环境中的应用

在研究空中爆炸及舰船密闭舱室爆炸时,提出了球面加载法对现有有限元程序进行改进,计算结果表明:球面加载法能有效改善现有有限元软件在计算冲击波在流场中衰减过快的弊端,且采用球面加载法得到的流场冲击波压力与理论值吻合良好.在此基础上,采用球面加载法对某舰密闭舱室遭受反舰导弹攻击发生爆炸时的破坏环境进行了计算,给出了密闭舱室爆炸时舰船的破坏环境.研究结果对开展相关的研究具有一定的参考价值.