低应变法在基桩垂直度检测中的仿真研究

通过将倾斜基桩中传播的应力波分解为纵波和弯曲波,基于应力波传播理论,对倾斜基桩桩顶不同拾震点信号特征与倾斜方向、倾斜角度的关系进行了数值仿真研究,并对仿真研究的结论与实体模型实验进行了比对,为基桩垂直度的检测提出了一种新途径。     

超高层建筑转换梁节点“L型”角钢连接器的应用

泰山基业（财富中心）工程在建筑标高100 m处设置转换层，型钢梁多向相交、钢筋纵横贯穿。通过分析、对比转换梁腰筋与型钢梁的连接方式，确定采用“L型”角钢连接器的方式，可以保证转换梁腰筋与型钢梁的连接质量。     

弯剪复合载荷作用下复合材料层合板屈曲的强度校核方法

基于复合材料各向异性板的大挠度方程，采用Ritz法和最小势能原理推导出了正交各向异性复合材料层合板在面内弯曲载荷作用下临界屈曲弯矩的解析解；给出了面内弯剪复合载荷作用下复合材料层合板屈曲的强度校核方法，并将本文方法所得结果与用有限元法（FEM）所得结果进行了比较。结果表明，本文方法与有限元方法相吻合，并且形式简洁，便于工程应用。     

推力矢量燃气舵特性的机理分析

为了研究燃气舵气动特性的形成机理,采用N-S方程模拟了推力矢量燃气舵表面压力分布,得到了不同舵偏角下燃气舵周围压力的变化曲线,分析了燃气舵表面不同位置压力的大小.结果表明,舵偏角的变化对燃气舵背风面的压力影响不大;随着舵偏角的增大,燃气舵迎风面的压力变化很大;在升力贡献方面,靠近根部区域大于梢部,最大厚度处上游区域大于下游.     

微射流驱动弯曲测试法测量微结构的弹性模量

提出了一种新颖的用于测量微结构力学性能的弯曲测试法——微射流驱动的弯曲测试法(microjet-driving microbending test method,JDBT)。该方法利用气体微射流连续冲击微结构,使之发生弯曲变形,通过获取结构的尺寸参数和形变位移,并代入结构的变形公式,从而反解出材料的力学性能参量。利用动量定理推导了微射流作用力公式,对某型号石英摆片式加速度计的敏感结构进行了理论建模,并用COMSOL MULTIPHYSICS有限元软件对理论公式进行了修正,接着通过JDBT实验得到了不同流量下的结构位移,最后将结构尺寸和结构形变位移代入修正后的理论公式,从而得到了石英玻璃的弹性模量约为71GPa,比纳米压痕仪测试的结果要小14%左右,与文献中提到的结果吻合较好。     

Misalignment-Induced Bending in Pin-Loaded Tensile-Creep Specimens

In this paper, we have examined the possibility that elastic bending induced by load misalignment can affect creep measurements on pin-loaded tension specimens of silicon nitride (Si₃N₄). We have shown that elastic bending at room temperature can be as great as 42% of the axial strain when clean pins were used but was reduced to ∼3% when lubricated pins were used. Creep tests at the same applied stress and temperature were conducted on two groups of Si₃N₄ test specimens: one group used clean pins, and the other group used lubricated pins. By measuring the shapes of the specimens before and after the creep tests, we have determined that the loading holes were slightly misaligned before the creep tests and that small amounts of bending were induced by the creep tests. Bending occurred both in the gauge section of the specimen and in the transition region between the gauge section and the heads of the specimen (the latter phenomenon is defined as hinge bending). Our study indicated that the secondary creep rate, the hinge bending, and the bending of the gauge section was not dependent on pin lubrication, because the results from the clean and lubricated groups were statistically indistinguishable. Hinge bending was dependent on initial misalignment of the loading holes, whereas bending of the gauge section was independent of such factors.     

滚转对用CCD组合测量弹目相对方位的影响

针对减旋机构的滚转角偏差会影响利用CCD组合测量弹目相对方位的精度,建立了描述转角偏差与弹目相对方位测量误差关系的数学模型,进行了仿真和试验,分析了仿真和试验结果.结果表明,转角偏差对弹目相对方位的测量精度影响较大,减旋机构的旋转控制精度是决定转角偏差大小的主要因素,转角偏差不宜超过5°.     

Influence of heat treatment conditions on bending characteristics of 6063 aluminum alloy sheets

Bending deformation behaviors of solution treated (ST), natural aged (NA) and T6 tempered 6063 aluminum alloy sheets were studied by three-point bending tests. The changes of bending force, interior angle, bending radius and sheet thickness in the fillet region were analyzed by experimental measurements and numerical simulations. The results showed that the bending characteristics were strongly dependent on the heat treatment conditions. The T6 alloy sheets were bent more sharply and local plastic deformation occurred severely in the fillet region. However, the ST and NA alloy sheets exhibited relatively uniform bending deformation and large bending radius. The bending force of T6 alloy was the highest, followed by the NA alloy and that of the ST alloy was minimum. After unloading, as compared with the ST and NA alloys, the springback of T6 alloys was markedly larger. The aging time showed a positive sensitivity on the springback and non-uniform bending deformability. The bending characteristics are attributed to the combined effects of yield strength, yield ratio and coefficient of neutral layer.     

Quasi-isotropic bending responses of metallic sandwich plates with bi-directionally corrugated cores

In order to reduce anisotropic behaviors of sandwich plates with open channel cores under the bending load, bi-directionally corrugated cores were introduced. Bi-directionally corrugated core has two additional design parameters related with a corrugation pass than uni-directionally corrugated core, so that its properties with respect to core orientations can be controlled. Sandwich plate with bi-directionally corrugated core is designed optimally so that beam buckling of face sheets is reduced drastically and anisotropic buckling behavior in the face sheets is minimized. The cores fabricated by a sectional forming process were bonded with face sheets by adhesive bonding. Three-point bending experiments were carried out with respect to core orientations. It has been shown from the experiments that sandwich plates with bi-directionally corrugated cores exhibit quasi-isotopic bending behaviors and structural performances in sandwich plates.     

Investigation of nanofluid bubble characteristics under non-equilibrium conditions

We report experimental and theoretical investigations of the bubble characteristics during the oscillatory growth period for several nanofluids. The nanoparticles were found to affect liquid–gas and solid surface tensions, which modulated the bubble contact angle, radius of triple line, bubble volume and the dynamics of bubble growth. To increase the accuracy of the Young–Laplace equation predictions during the bubble growth in the oscillatory period, a new method multi-section bubble (MSB) approach was developed. In this method, the bubble was divided into n sections (i.e., n = 1:N) and the Young–Laplace equation was solved for each section individually. As N increases, within each section the effects of inertia force and viscosity become reduced comparing to that of the liquid-gas surface tension. Unlike the conventional Young–Laplace approach (i.e., N = 1), the new approach is able to predict the bubble characteristics reliably in the following cases: (a) the oscillatory period when bubble is fluctuating; (b) the departure period when bubble is stretched upward, right before departure; and (c) the high shear stress condition when gas velocity is relatively high.