爆轰驱动带有附加质量的筒壳大变形动力学分析

依据大变形理论，考虑到筒壳和动能杆的冲击接触并视动能杆为附加质量，求解了内爆炸载荷下具有附加质量的筒壳径向膨胀的动力学响应。给出了瞬态的速度场分布及筒壳断裂时杆和壳体的速度，计算结果与实验结果吻合。

椭偏光学显微成像系统中的图像采集及处理技术

针对椭偏光学显微成像系统及其成像(简称“椭偏成像”)特点，提出了扩展图像量化等级法、快速采样-时间积分法和多采样点平均法以改善椭偏成像质量和样品表面定量分析的可靠性，并给出理论分析及实验结果。这些图像采集和图像处理技术在椭偏光学显微成像系统中行之有效，同时也适用于类似的图像处理系统。

泥石流反粒径分布的一种定性解释

假设泥石流中的粗颗粒（如石块等）以跳跃的方式前进，通过分析单个颗粒在定常充分发展的流场中的运动，给出了单一起跳速度下以及具有一定分布的起跳速度下，颗粒数密度随高度的分布，并给出了起跳粒径有分布时颗粒的平均粒径随高度的分布，定性地解释了泥石流中的反粒径分布现象。

Impact response and failure mechanisms of ultrahigh modulus polyethylene fiber composites and polyethylene fiber-carbon fiber hybrid composites

The impact response and failure mechanisms of ultrahigh modulus polyethylene (UHMPE) fiber composites and UHMPE fiber-carbon fiber hybrid composites have been investigated. Charpy impact, drop weight impact and high strain rate impact experiments have been performed in order to study the impact resistance, notch sensitivity, strain rate sensitivity and hybrid effects. Results obtained from dynamic and quasi-static measurements have been compared. Because of the ductility of UHMPE fibers, the impact energy absorption of UHMPE fiber composites is very high, thereby leading to excellent damage tolerance. By hybridizing with UHMPE fibers, the impact properties of carbon fiber composites can be greatly improved. The impact and shock failure mechanisms of these composites are discussed.

Measurement of Mechanical Properties of MEMS Materials

微电子机械系统（MEMS）技术的迅速崛起,推动了所用材料微尺度力学性能测试技术的发展.首先按作用方式将实验分成压痕/划痕、弯曲、拉伸、扭转四大类,系统介绍检测MEMS材料微尺度力学性能的微型试样、测试方法及其实验结果.测试材料主要有硅、氧化硅、氮化硅和一些金属.实验结果主要包括基本的力学性能参数如弹性模量、残余应力、屈服强度、断裂强度和疲劳强度等.最后,简要分析了未来的发展需求.

探求高效裂解生产乙烯的新途径

乙烯是裂解反应过程中的中间产物,其收率随反应时间变化.在最佳反应时间,收率最高.裂解反应温度愈高,峰值收率愈高,最佳反应时间则愈短.当前通用的竖管裂解炉难以满足大幅度提高乙烯收率并降低生产成本的要求.评述了几种激波加热方法的优缺点.简要描述了我们目前正在研究中的反向射流混合加热方法.

A New Finite Element Method for Strain Gradient Theories and Applications to Fracture Analyses

A new compatible finite element method for strain gradient theories is presented. In the new finite element method, pure displacement derivatives are taken as the fundamental variables. The new numerical method is successfully used to analyze the simple strain gradient problems – the fundamental fracture problems. Through comparing the numerical solutions with the existed exact solutions, the effectiveness of the new finite element method is tested and confirmed. Additionally, an application of the Zienkiewicz–Taylor C1 finite element method to the strain gradient problem is discussed. By using the new finite element method, plane-strain mode I and mode II crack tip fields are calculated based on a constitutive law which is a simple generalization of the conventional J2 deformation plasticity theory to include strain gradient effects. Three new constitutive parameters enter to characterize the scale over which strain gradient effects become important. During the analysis the general compressible version of Fleck–Hutchinson strain gradient plasticity is adopted. Crack tip solutions, the traction distributions along the plane ahead of the crack tip are calculated. The solutions display the considerable elevation of traction within the zone near the crack tip.

Partition Energy Absorption of Axially Crushed Aluminum Foam-Filled Hat Sections

The "interaction effect" between aluminum foam and metal column that takes place when foam-filled hat sections (top-hats and double-hats) are axially crushed was investigated in this paper. Based on experimental examination, numerical simulation and analytical models, a systemic approach was developed to partition the energy absorption quantitatively into the foam filler component and the hat section component, and the relative contribution of each component to the overall interaction effect was therefore evaluated. Careful observation of the collapse profile found that the crushed foam filler could be further divided into two main energy-dissipation regions: densified region and extremely densified region. The volume reduction and volumetric strain of each region were empirically estimated. An analytical model pertinent to the collapse profile was thereafter proposed to find the more precise relationship between the volume reduction and volumetric strain of the foam filler. Combined the superfolding element model for hat sections with the current model according to the coupled method, each component energy absorption was subsequently derived, and the influence of some controlling factors was discussed. According to the finite element analysis and the theoretical modeling, when filled with foam, energy absorption was found to be increased both in the hat section and the foam filler, whereas the latter contributes predominantly to the interaction effect. The formation of the extremely densified region in the foam filler accounts for this effect.

用地质统计学计算土层相关尺度

随机场理论可以用来模拟土工参数的空间变异性，而地质统计学也借助于随机场理论对自然资源进行估计、模拟和评价，很明显随机场理论是两类应用的共同理论基础，因而借助于发展较成熟的地质统计学理论估算土层相关尺度应是一条有效的途径。本文论述了该方法的理论基础，认为求取变差函数与求相关函数是等价的，建立并证明了八类理论变差函数与其相应的相关距离之间的解析关系，介绍了具体的计算步骤：计算实验变差函数、选择合适的理论变差函数模型、最优拟合实验变差函数、计算相关距离，以实例说明了实际步骤以及结果的有效性和实用性。

Effects Analysis on the Mechanical Properties of Nanocrystalline Materials

Nanocrystalline materials are characterized by a typical grain size from 1 to 100nm. In order to study the nanocrystalline properties of nanocrystalline materials, we chose nanocrystalline coppers as the research object. The uniaxial tensile deformation of computer produced nanocrystalline coppers is simulated by using molecular dynamics with Finnis-Sinclair potential. The mean grain size of simulated nanocrystalline coppers is varied within the 5.38 to 1.79 nm range. The strength, Young's modulus and stress-strain are strongly depended on the grain size and nanocrystalline structure. The simulated nanocrystalline coppers show a reverse Hall-Petch effect.

液层厚度对浮力-热毛细对流面型的影响

将Michelson光学干涉测量系统与图像处理技术相结合,发展形成一种实时诊断热毛细对流和浮力对流流体表面形貌的实验测量系统.采用光学干涉测量方法研究了两端带有温差的矩形池内薄层流体的对流、表面变形、以及表面波的基本问题.应用Fourier变换方法对实验结果进行计算和分析,得到了流体表面变形和表面波的定量的实验结果.实验结果表明了在浮力-热毛细对流的发展过程中,首先出现流体的表面变形,之后在该变形的基础上,叠加了一个表面波的信息,该表面变形和表面波与流体的温度梯度、表面张力、以及浮力有直接的关系;表面波隐藏在表面变形内.

Fourth order accurate compact scheme with group velocity control (GVC)

For solving complex flow field with multi-scale structure higher order accurate schemes are preferred. Among high order schemes the compact schemes have higher resolving efficiency. When the compact and upwind compact schemes are used to solve aerodynamic problems there are numerical oscillations near the shocks. The reason of oscillation production is because of non-uniform group velocity of wave packets in numerical solutions. For improvement of resolution of the shock a parameter function is introduced in compact scheme to control the group velocity. The newly developed method is simple. It has higher accuracy and less stencil of grid points.

工程地质力学及其应用中的若干问题

工程地质力学是以工程为目的研究地质体变形破坏规律的科学。地质体具有非连续、非均匀、流-固耦合以及未知的初始状态的特性，工程地质力学的关键科学问题包括如何判断地质体的当前状态、描述地质体的力学特性以及分析地质体由连续到非连续的演化过程。工程地质力学研究应当以地学为基础、力学为手段、工程为目的，迫切需要解决的工程问题包括探测地质体的几何和力学特性，给出地质体稳定性的分析方法、地质工程设计依据以及地质灾害的预测预报方法。无论是模型实验还是模拟实验的结果能否回答工程问题取决于对地质条件的认知程度，但是，实验研究可以作为验证数值模拟结果的有力工具；地质调查和现场测量是工程地质力学必不可少的组成部分，地质体的力学分类体现了地学的基础作用，可实现地质环境描述定量化。针对工程需求建立力学模型可主要考虑含结构面岩体、土石混合体以及地质中裂隙流和岩土体的相互作用；实验室岩块实验的试样尺寸应作为地质体多尺度计算模型中的基本尺度。工程地质力学的主要研究内容应当包括给出关键的力学测量参数、研究获得这些参数的方法及相关的仪器：在提出和完善力学模型的同时，应更加注重新的计算方法的验证以及工程应用研究。

Conjugate Model for Heat and Mass Transfer of Porous Wall in the High Temperature Gas Flow

Heat and mass transfer of a porous permeable wall in a high temperature gas dynamical flow is considered. Numerical simulation is conducted on the ground of the conjugate mathematical model which includes filtration and heat transfer equations in a porous body and boundary layer equations on its surface. Such an approach enables one to take into account complex interaction between heat and mass transfer in the gasdynamical flow and in the structure subjected to this flow. The main attention is given to the impact of the intraporous heat transfer intensity on the transpiration cooling efficiency.

摄动有限差分方法研究进展

摄动有限差分(PFD)方法,既离散微商项也离散非微商项(包括微商系数)，在微商用直接差分近似的前提下提高差分格式的精度和分辨率。PFD方法包括局部线化微分方程的摄动精确数 值解(PENS)方法和摄动数值解(PNS)方法以及考虑非线性近似的摄动高精度差分(PHD)方法。论述了这些方法的基本思想、具体技巧、若干方程(对流扩散方程、对流扩散反应方程、双 曲方程、抛物方程和KdV方程)的PENS、PNS和PHD格式，它们的性质及数值实验。并与有关的数值方法作了必要的比较。最后提出值得进一步研究的一些课题。