饱和脆性岩石在反平面剪切条件下的应变局部化分析

对反平面剪切条件下饱和脆性岩石中单个剪切带的空间发展进行了分析。将饱和岩石视为固液两相介质, 用小扰动方法进行稳定性分析。固相视为弹塑性介质,是应变、应变率和孔隙水压力或应力历史的函数,而液体满足达西定律。考虑惯性效应和相间作用,假设固相是可压的。研究结果表明,如果比例加载路径与局部化方向的夹角为π/2,则变形是稳定的,这相当于中性加载:夹角大于π／2的情况相当于弹性卸载:而夹角小于π／2的情况相当于加载,且当夹角等于0°时,失稳发展最快。扰动频率α正值的条件是要求孔压软化效应超过应变硬化效应。在两种极端情况下——长波和短波,饱和脆性岩石总是稳定的。

Experimental Study of the Earthquake Recurrence Period and the Trend of Post-Seismic Development

In order to study the earthquake recurrence and the characteristics of earthquake series, rupture tests of rock samples and plexiglass samples were made. On rock samples, a number of acoustic emission (AE) and strain measuring points were deployed; the load was one side direct shear. The variation characteristics of AE and strain at different detecting points around the extra large fracture were observed and studied. On plexiglass samples, a series of inclined cracks were prefabricated by a small-scale compressive testing machine. The samples were then loaded on a shockproof platen, when the samples were loaded, the stress intensity factor (SIF) was determined by the laser interferometric technique and shadow optical method of caustics. The fracture conditions such as material toughness around the extra large fracture were also studied. From those experimental results and the theory of fracture mechanics, the earthquake recurrence period and the trend of post-seismic development were studied.

Study on Mechanical Properties of Nanocrystal Surface Layer of an Aluminum Alloy

The nanocrystal surface layer of an aluminum alloy induced by High Speed Shot Peening (HSSP) was investigated in this paper. The results of nanoindentation experiment show that the elastic modulus and the hardness of nanocrystal surface layer increased,by 8% and 20%, respectively. The elastic modulus and the hardness appear to be independent of the distance from nanocrystalized surface and the process time.

Damage evolution, localization and failure of solids subjected to impact loading

In order to reveal the underlying mesoscopic mechanism governing the experimentally observed failure in solids subjected to impact loading, this paper presents a model of statistical microdamage evolution to macroscopic failure, in particular to spallation. Based on statistical microdamage mechanics and experimental measurement of nucleation and growth of microcracks in an Al alloy subjected to plate impact loading, the evolution law of damage and the dynamical function of damage are obtained. Then, a lower bound to damage localization can be derived. It is found that the damage evolution beyond the threshold of damage localization is extremely fast. So, damage localization can serve as a precursor to failure. This is supported by experimental observations. On the other hand, the prediction of failure becomes more accurate, when the dynamic function of damage is fitted with longer experimental observations. We also looked at the failure in creep with the same idea. Still, damage localization is a nice precursor to failure in creep rupture.

基于Profibus的激光加载热疲劳实验控制系统

采用激光作为活塞热疲劳模拟实验的热源.为模拟活塞上表面的温度波动,设计了基于Profibus的实验控制系统,对激光器的开启、关闭及输出功率进行控制.实验结果表明,该系统实现了活塞热疲劳实验的设计要求,具有实验周期短、可靠性高等优点.

压力热回收锅炉的结构和技术要点

压力热回收锅炉是整体煤气联合循环（ＩＧＣ）电站的主要设备之一，在国内还是一项新兴技术。文中介绍压力热回收锅炉的结构特点和运行特性，并结合我国实际情况较为详细地介绍压力热回收锅炉的研究内容，对它的发展趋势作简要说明，为我国开展和引进ＩＧＣＣ示范电站提供有益的分析。

A Quantitative Analysis of the Effect of Laser Transformation Hardening on Crack Driving Force in Steels

A mechanical model of a laser transformation hardening specimen with a crack in the middle of the hardened layer is developed to quantify the effects of the residual stress and hardness gradient on crack driving force in terms of J-integral. It is assumed

Experimental investigation of the shear strength of a unidirectional carbon/aluminum composite under dynamic torsional loading

In this paper, the dynamic shear strength of a unidirectional C/A356.0 composite and A356.0 alloy, respectively, are measured with a split Hopkinson torsional bar (SHTB) technique. The results indicate that the carbon fibers make very little contribution to the enhancement of the shear strength of the matrix material. The microscopic inspections on the fracture surface of the composite show a multi-scale zigzag feature. This implies that there is a complicated shear failure mechanism in the unidirectional carbon/aluminum composite.

内旋流流经床中气泡运动规律研究

利用摄机相研究了内旋流流化床固相流场及气泡特性，表明：非均匀布风是形成内旋流的关键最佳高风区，低风区流化倍率为初始流化速度的６倍和１.５倍；随着气泡的上升，其体积不断增大；…

Simulation of Free-Surface Flow in a Tank Using the Navier-Stokes Model and Unstructured Finite Volume Method

Modelling free-surface flow has very important applications in many engineering areas such as oil transportation and offshore structures. Current research focuses on the modelling of free surface flow in a tank by solving the Navier-Stokes equation. An unstructured finite volume method is used to discretize the governing equations. The free surface is tracked by dynamically adapting the mesh and making it always surface conforming. A mesh-smoothing scheme based on the spring analogy is also implemented to ensure mesh quality throughout the computaiton. Studies are performed on the sloshing response of a liquid in an elastic container subjected to various excitation frequencies. Further investigations are also carried out on the critical frequency that leads to large deformation of the tank walls. Another numerical simulation involves the free-surface flow past as submerged obstacle placed in the tank to show the flow separation and vortices. All these cases demonstrate the capability of this numerical method in modelling complicated practical problems.

高寒草甸地区陆面过程耦合模式与辐射研究

论述了陆气相互作用的研究意义与现状。在原有研究工作基础上，针对中国科学院高寒草甸站地区陆气水热传输过程，提出了一个多层陆面过程耦合模式，特别给出了导水率的计算模型和修正后的根系吸水模式，对植物内部湍流交换的物理过程作了深入研究。还介绍了当地的气候概况和，野外观测情况，利用本模式对中国科学院高寒草甸站地区陆气水热交换过程进行了数值模拟，模拟结果与实测值吻合较好，证明该模式成功地模拟了陆气相互作用过程，可为当地合理利用水热资源提供科学依据，为了解植被在陆气相互作用的影响，本文又进行了敏感性数值试验。

Experimental Studies of the Material Properties of the Forewing of Cicada (Homoptera, Cicadidae)

Detailed investigations on the structural and mechanical properties of the forewing of the cicada were carried out. Measurement of the structures of the wings showed that the thickness of the membrane of each cell and the diameter of each vein were non-uniform in both the longitudinal and transverse directions, and their means were approximately 12.2 and 133.3 mum, respectively. However, the aspect ratios of the wings and the bodies were quite uniform and were approximately equal to 2.98 and 2.13, respectively. Based on the measured thickness, mass and area of the membranes of the cells, the mean density and the mean area density of the wing were approximately 2.3 g cm(-3) and 2.8 x 10(-3) g cm(-2), respectively. In addition, the diameters of the veins of the wings, including the diameters of the holes in the vein of the leading edge, were examined. The mechanical properties of the wing were investigated separately by nanoindentation and tensile testing. The results indicated that the mean Young's modulus, hardness and yield stress of the membranes of the wings were approximately 3.7 Gpa, 0.2 Gpa and 29 Mpa, respectively, and the mean Young's modulus and strength of the veins along the direction of the venation of wings were approximately 1.9 Gpa and 52 Mpa, respectively. Finally, the relevant results were briefly analyzed and discussed, providing a guideline to the biomimetic design of the aerofoil materials of micro air vehicles.

生物分子在Ni纳米膜表面吸附的力学特性:分子动力学模拟

采用COMPASS力场,通过分子动力学模拟,研究了Ni纳米薄膜的弹性模量的尺寸效应,以及生物分子吸附在Ni表面对其力学性能的影响.计算结果表明,随着厚度的增大,吸附强度也在增强;Ni纳米薄膜的弹性模量随着膜厚的减小而减小.氨基酸在Ni表面的吸附能够提高其弹性模量1～2 GPa,并且表明分子的取向是重要的影响因素.