Golden Ratio-Based and Tapered Diptera Inspired Wings： Their Design and Fabrication Using Standard MEMS Technology

This work presents our understanding of insect wings, and the design and micromachining of artificial wings with golden ratio-based and tapered veins. The geometric anisotwpy of Leading Edge Veins （LEVs） selected by Diptera has a function able to evade impact. As a Diptera example, the elliptic hollow-LEVs of cranefly wings are mechanically and aerodynamically significant. In this paper, an artificial wing was designed to be a fractal structure by mimicking cranefly wings and incorporating cross-veins and discal cell. Standard technologies of Microelectromechanical Systems （MEMS） were employed to materialize the design using the selected material. One SU-8 wing sample, light and stiffenough to be comparable to fresh cranefly wings, was presented. The as-prepared SU-8 wings are faithful to real wings not only in weight and vein pattern, but also in flexural stiffness and mass distribution. Thus our method renders possible mimickine with good lidelity of natural wings with complex geometry and morphology.

测定纱线弯曲刚度的实验方法

为了研究织机上的打纬和织物形成过程,本文提出了以频闪摄影测定纱线弯曲刚度的实验方法,并运用该方法对不同纱线的弯曲刚度进行了测定。

大面开槽钢纤维粉煤灰双免砖的抗折性能研究

在粉煤灰免烧免蒸砖大面带凹槽的基础上,通过在砖体内掺加钢纤维的方法,研究大面开槽钢纤维粉煤灰双免砖的抗折性能。试验比较了4种不同类型的粉煤灰双免砖,结果表明:凹槽的存在,不仅削减了砖块的截面高度还使得凹槽处产生了应力集中效应,砖体的抗折强度较标准砖降低了31.43%;而在带凹槽的砖体内掺加体积含量为0.6%的钢纤维后,较之于标准砖其抗压强度提高不明显,但抗折强度提高了32.50%,折压比为标准砖的1.25倍。证明了钢纤维的掺入不仅能有效降低凹槽处的应力集中效应,还能较大幅度提高砖体的抗折性能及折压比。

弹性矩形板的一般精确解

本文讨论了弹性矩形板(Reissner板和Kirchhoff板)的一般精确解。选择三角级数和多项式组成的挠曲函数。它满足板的控制微分方程以及给定的边界条件,从而得到不同边界条件(自由,简支,固定)问题的精确解。文中包括一个悬臂矩形薄板的数值例题。

预应力混杂纤维板增强混凝土梁的抗弯试验研究

通过对不同模量碳纤维和玄武岩纤维混杂成的纤维板增强钢筋混凝土梁(C/BFRP混凝土复合梁)试验,研究不同混杂参数及预应力对复合梁受弯性能的影响,并对复合梁的承载能力、刚度、挠度及延性进行讨论。试验结果表明,预应力C/BFRP能有效提高钢筋混凝土梁的受弯承载能力,延缓梁裂缝的出现,提高梁的延性,同时复合梁屈服后有较高的二次刚度。