宾汉流体阻力近似解公式精度的优化提高

针对前苏联学求解宾汉流体布金汉方程的阻力近似解公式，其与精确解最大偏差为6．7％，首次通过数学分析和三维优化计算，改变公式中的参数，使偏差大幅度降低．偏差是参数和核心流相对半径r^-O的函数，用极限判定了在r^-O闭区间内的连续性和间断点，为降低偏差提供了依据．绘制了偏差三维变化图，应用切片平面解决了多峰曲面的极值问题．最终优化出的参数使公式的最大偏差为2．6％，比6．7％降低了4．1％，优化后的公式，在管道输送阻力计算中更有实用价值．     

Creeping flow past and within a permeable spheroid

Flow past and within an isolated permeable spheroid directed along its axis of symmetry is studied. The flow velocity field is solved using the Stokes creeping flow equations governing the fluid motion outside the spheroid, and the Darcy equation within the spheroid. Expressions for the hydrodynamic resistance experienced by oblate and prolate spheroids are derived and analyzed. The limiting cases of permeable circular disks and elongated rods are examined. It is shown that the spheroid’s resistance varies significantly with its aspect ratio and permeability, expressed via the Brinkman parameter.     

动载下韧性撕裂在三种管线钢材中传播阻力的研究

阐述了用实验确定在常温及静载和动载条件下韧性撕裂在三种管线钢材中传播时的断裂比能值。实验中采用了销钉加载双面开槽的双悬脊梁(DCB)试件。应用能量平衡法对实验结果进行了分析。考察了加载速率和试件厚度对撕裂韧性的影响。结果表明,管线钢材对韧性撕裂传播的阻力在动载条件下增大,对较薄的试件及应变率敏感性较高的材料其增大更为明显。对于纯剪切断裂的传播来说,撕裂韧性一般随试件厚度的增大而增加。     

Effect of inflation pressure on motion resistance ratio of a high-lug agricultural tyre

A single wheel tyre facility at University Putra Malaysia (UPM) was used to check the validity of Wismer–Luth and Brixius equations in predicting the motion resistance ratio of a high-lug agricultural tyre and to investigate the effect of inflation pressure. A Bridgestone 5-12, 4 ply, lug M was tested on sandy-clay-loam soil. The experiments were conducted by running the tyre in towing mode. Three inflation pressures (i.e., 166, 193 and 221 kPa) were investigated and wheel numerics ranging between 0 and 70. The analysis of covariance (ANCOVA) revealed that both inflation pressure and wheel numeric have significant effects on tyre motion resistance ratio. Regression analysis was also conducted to determine the closeness of fit for Wismer–Luth’s and Brixius’ equations in predicting the motion resistance ratio of the tested tyre. Finally, three new logarithmic models for tyre motion resistance were formulated. The advantage of reducing tyre inflation pressure from 221 (nominal pressure) to 193 kPa on the motion resistance ratio of the high-lug agricultural tyre was pronounced. However, the tyre’s motion resistance ratio deteriorated with further reduction in tyre inflation pressure from 221 (nominal pressure) to 166 kPa.     

轴线平行圆柱体滚动接触时的轴向移动阻力

应用摩擦学中的预位移原理，求解轴线平行的两粗糙圆柱体滚动接触时的轴向移动阻力，分析了轴移速比、法向接触载荷、圆柱体表面粗糙层参数对轴向移动阻力的影响，并给出了计算轴向移动阻力的简化公式．     

用电阻量测方法研究蠕变状态下的金属损伤

本文建议一种量测蠕变下金属损伤的方法。与其它方法相比,这个方法可用于进行在蠕变试验过程中的损伤测量,而无需使试件卸载或冷却。用此方法对试验数据进行加工就可得到在蠕变过程中的试验损伤曲线。对这些曲线的分析导致结论:材料破坏时的损伤是所加应力的递减函数。这一结论是以前所得理论结果的试验验证。     

Elastic contact stiffness and contact resistance for the Weierstrass profile

The Weierstrass series comprises a system of superposed self-affine sine waves that can be used to define a simple idealization of a two-dimensional fractal rough surface profile. The load-compliance relation for the contact of this profile with a rigid plane is here estimated using Westergaard's solution for the contact of a single sine wave with a plane and various approximations concerning the interaction of the different terms in the series. These approximations are compared with a numerical solution for the contact of the profile defined by the first few terms of the series. Once the load-compliance relation is established, the electrical contact resistance can be determined, using an analogy between the conduction and incremental elastic contact problems. The results show that these simple estimates give quite good predictions of the relations between load, compliance and contact resistance. They also confirm that these relations are largely determined by the coarse scale features of the surface profile, in contrast to the predictions of classical asperity model theories.     

金属基耐磨铸造表面复合材料的现状及其今后研究工作的主攻方向

为了推动国内在金属基耐磨铸造表面复合材料领域的基础理论研究和应用的发展，对这类复合材料的制造工艺、耐磨性能和影响其质量的有关因素进行了综合介绍与评述。目前，金属基耐磨铸造表面复合材料的发展方兴未艾，尽管其制造工艺的研究，特别是对于它的摩擦学性能和影响其质量的因素之研究报道都还不多，然而毕竟已经取得了不少成果，这为它的进一步发展奠定了基础。通过对几个方面已经成功应用和可望投入应用之实例的简明阐述，展现了金属基耐磨铸造表面复合材料良好的实用前景，并就其今后的研究工作提出了几个值得重视的主攻方向。应当特别还强调指出的是，在对这类复合材料深入进行基础理论研究的同时，还必须大力开展其在工程上的应用研究，以不断拓展它的适用范围。     

用内埋电阻丝检测复合材料层压板损伤的可行性研究

本文利用低速冲击装置冲击四周简支复合材料板试样，用以模拟低速低能量冲击而造成的分层损伤；用中心钻孔复合材料板试样用以模拟因高速冲击而造成穿透性损伤。探讨利用内埋康铜电阻丝阵列构成检测网络实现对复合材料中损伤位置和损伤程度检测。这种方法可利用较成熟的电测技术，装置简单，具有良好的工程应用前景     

Interface thermal resistance and thermal conductivity in composites – an abrupt junction thermal diode model

An abrupt junction diode model is proposed to study the interface thermal resistance and thermal conductivity of composite. We have demonstrated that the structure of thermal diode greatly influences the heat flow and hence it is possible to regulate the heat flow via the geometry of the diode. The composite materials can significantly reduce the thermal conductivity compared to an equivalent single material. By tuning the mass ratio of oscillator of right segment to that of oscillator of left segment of the composite, _MR/_ML$M_{\mathrm{R}}/M_{\mathrm{L}}$, crossover between negative differential thermal resistance and positive differential thermal resistance as well as figure of merit for composite material can be tuned. It is also seen that the composite will work as a better thermal insulating material than its pure constituent materials.