NiAl弥散增韧Al2O3复相陶瓷

以金属间化合物NiAl为弥散增韧相,制备了氧化铝复相陶瓷,深入探讨了其性能及增韧效果与显微结构之间的关系.结果表明1 600℃下真空烧结所制备的Al2O3复相陶瓷(φ(NiAl)=20%)断裂韧性为K1C=8.2 Mpa·m1/2,比单体系氧化铝陶瓷(K1C=4.84 Mpa·m1/2)提高了约68%.     

Sialon陶瓷的研究进展

简要论述了Ｓｉａｌｏｎ陶瓷的结构和性质,介绍了目前国内外Ｓｉａｌｏｎ陶瓷的研究概况,系统阐述α’－Ｓｉａｌｏｎ陶次必Ｓｉａｌｏｎ复相陶瓷的研究进展。     

复合材料圆孔应力的正交各向异性光弹性分析

本文根据 Sampson 提出的应力—光学定律,对正交各向异性复合材料带有圆孔的有限宽板进行了分析研究,得到了复合材料带有圆孔板孔边的应力分布状态.本文的实验结果与正交各向异性受拉带孔无限和有限宽板的两种关于圆孔孔边应力分布状态的理论解符合较好.     

纳米材料在陶瓷领域的应用

介绍了纳米材料对陶瓷材料的力学性能(如强度与韧性、超塑性、烧结性能)的影响;简要概述了纳米单相陶瓷和复相陶瓷的制备方法;综述了近年来纳米材料在陶瓷材料研究中的进展情况,并对纳米材料对陶瓷材料存在的问题及应用前景进行了展望.     

巨型变压器油箱的光弹性实验应力分析

本文利用光弹性实验的直观、适于选型等特点,为巨型钳夹式变压器油箱的箱耳选型。由于箱耳与油箱纵向侧壁框架连成一体,故取油箱的侧壁框架和箱耳为一体来进行研究。但侧壁框架是由薄壁槽形截面杆件组成,其几何相似模型制做困难,本实验将侧壁框架设计成矩形截面的变态模型,模型设计公式根据相似理论导出;模型箱耳与实物完全相似,由此模型所测得的箱耳的应力分布是符合实际情况的。通过光弹性实验最终为钳夹式变压器油箱选出了合理形状。     

复合相层电陶瓷的阻抗谱研究

用低频交流阻抗分析法对相复合导电化的陶瓷的导电机构进行了研究，结果表明，导电通路虽由导电相粒子连接而成，但导电相粒子间的接触电阻也电构成样品电阻的重要部分，它随温度上升而下降，使样品呈半年体性。     

正交异性光弹性实验应用分析的矩阵理论

应力-光定律是光弹性实验应力分析的基本理论,从正交异性光弹性的物理机制出发,运用矩阵理论,建立了正交异性光弹性应力-光定律,讨论了正交异性光弹性试验方法。     

光弹性实验中研究应力集中的两个问题

首先简单介绍了光测弹性力学的发展情况及光弹性实验，然后就光弹性实验中的应力集中问题进行了详细的分析和讨论，得出了应力集中点最大应力确定的方法和求应力集中模拟问题尤其是非相似模拟求应力集中问题的方法。     

Tribological Properties of PVA-H Composites Reinforced by Nano-HA Particles

The friction and wear behaviors of tribological mechanical components were studied on a four-ball tester under dry conditions, and the wear mechanism was analyzed by observed worn surface using a scanning electron microscope （SEM）. It was found that the friction and wear properties were improved by the addition ofnano HA particles. The composite containing 1 wt% nano HA had the optimum friction coefficient. It is also found that the addition of nano HA increases the wear resistance of oure PVA-H and PVA-H composites.     

Characterization of EBPVD micro-layer composites and simulation of its internal stress state

Based on the basic operating principal and the technology characteristic of electron beam physical vapor deposition(EBPVD) technique, EBPVD was used to prepare the micro-layer composites. The effect on the substrate preheating temperature was taken into accounts and the finite element analysis package ANSYS was used to simulate the internal stress field and the potential displacement changing tendency. The results show that one of the most important quality factors on the judgment of micro-layer composites is the adhesion between the substrate and the deposition layers as well as among the different deposition layers. Besides the existance of temperature gradient through the thickness of layers, the main reason for the internal stress in micro-layer composites is the mismatch of various properties of the layer and the substrate of different thermal expansions and crystal lattice types. With the increase of substrate preheating temperature, the inter-laminar shear stress also takes on a tendency of increase but the axial residual stress decrease.     

Fabrication of Ceramic Composites by Directed Metal Oxidation

To explain the growth mechanism of Al2O3/Al Lanxide composites , the dynamics of the directed oxidation of Al-Mg-Si alloys are analyzed. The experimental methods to produce Lanxide composites by directed oxidation of metal melts at high temperatures are presented. The effect of the processing factors on the microstructures and properties of Al2O3/ Al composites and enforced Al2O3/Al composites is also analyzed. Compared with sintering ceramic composites, the advantages of Lanxide process and Lanxide materials are as following : it is a near net shaped process ; the process is very simple ; the microstructures and properties of Lanxide materials can be adjusted ; and this process can be used to infiltrate ceramic fiber or particle preforms.     

WC颗粒增强高锰钢基表面复合材料组织和硬度的研究

研究了采用V-EPC铸渗方法制备WC颗粒增强高锰钢基表面复合材料时,合金粉末中EPS珠粒的加入量对形成的铸渗复合层组织和硬度的影响．试验结果表明,复合层的质量随着EPS珠粒的加入量增加而得到改善,复合层的硬度由表及里呈现先增后降的趋势．EPS珠粒加入量为14％（体积分数）时得到的组织最致密,缺陷最少;超过14％时,随着EPS珠粒加入量的继续增加,复合层组织中缺陷的数量又开始增多．     

纺织结构复合材料增强纤维的应力与模量分析

采用弹性力学方法，根据加捻纱线的工艺特点，考虑了纱线的拉伸和扭转特性，导出了纱线的力──应变关系，进而得出纺织复合材料中纱线模量的一般表达式。     

纳米氧化铝颗粒增强铜-碳基复合材料的磨损性能

用MA技术制备了C体积分数为10%的Cu-C固溶体粉体,用溶胶-凝胶(sol-gel)烧结技术制备了平均尺寸为12 nm的γ-Al2O3颗粒和用SPS方法制备了纳米Al2O3颗粒增强Cu-C固溶体基复合材料。采用X射线衍射仪对MA粉体、干凝胶和煅烧粉体进行了物相分析;通过JSM-5500LV型扫描电镜对磨损表面形貌进行观察分析并分析其磨损机制;使用MG-2000型高温摩擦磨损试验机对制备的复合材料进行了干摩擦实验并测定其磨损量。结果表明:纳米氧化铝颗粒体积分数及磨损载荷对复合材料摩擦磨损特性有显著影响,纳米氧化铝的体积分数从0%增加到2%,Cu基复合材料的磨损量从6.2 mg降到2.1 mg。     

Influences of interphase on dynamic effective properties of composites reinforced by dispersed spherical particles

The influences of interphase on dynamic effective properties of composites reinforced by randomly dispersed spherical particles were studied. A thin homogeneous elastic interphase with different shear and bulk moduli, located between the reinforced particle and the host matrix, was introduced to model the interfacial bonding state. The effects of such an interphase on the coherent plane waves were studied numerically. Numerical simulations were carried out for SiC-Al composites with four typical cases of interphase. It was found that the property of interphase has significant influences on the effective propagation constants of coherent waves and the dynamic effective elastic moduli of the composites. The influences on the coherent longitudinal wave and the coherent shear waves were different and dependent upon the frequency range. Moreover, several imperfect interface models, i.e., the spring model, mass model, and spring-mass model, were studied numerically and compared with the interphase model. It was found that the spring model is a more suitable model than the mass model for the light and weak interphase whereas the mass model is a more suitable model than the spring model for the heavy and strong interphase.     

基于内力分配法的组合梁徐变应力重分布实用计算

为了获得组合梁徐变应力重分布的计算公式,以一个单轴对称并受到弯矩和轴力作用的组合梁截面为研究对象,建立混凝土徐变的微分本构关系,采用内力分配法得到组合梁弯矩和轴力重分布的微分方程组。为了避免求该方程组的精确解所需复杂的数学计算,通过有效的简化获得方程组的实用近似解,并通过算例进行精确性验证。计算结果表明：方程组的近似解与精确解的误差非常小,能达到合理的计算精度;混凝土徐变对组合梁长期应力影响显著,计算时应得到足够的重视。文中采用的内力分配法适用性较广,无论是何种荷载形式,不管结构是静定还是超静定,只要内力能换算成作用在组合梁截面中和轴处的弯矩和轴力,都可以使用该方法。     

Special hybrid stress element for stress analyses around circular cutouts in laminated composites

A 3-dimensional hybrid stress element with a traction-free cylindrical surface based on a modified complementary energy principle has been derived for efficient and accurate analysis of stress concentration around circular cutouts in thin to thick laminated composites. New expressions of six stress components are developed by using three stress-functions in cylindrical co-ordinates, so that the homogeneous equilibrium equations, the interlayer surface transverse-stresses and the traction-free boundary condition on the cylindrical surface are satisfied exactly, while the interelement traction continuity has been relaxed via the Lagrange multiplier method. Transverse-shear deformation effects are incorporated in each layer with displacement continuity enforced along interlayer surface. Selected examples are used to demonstrate the efficiency and accuracy of the present special element.     

碳纳米管增强钛基复合材料的界面应力分布

为了了解工业领域中综合性能优异的金属基复合材料,采用结构分析软件ANSYS建立了有限元模型,研究了复合材料界面应力场的分布情况.结果表明,在受压载荷作用下,钛基复合材料发生屈服现象的可能性较小,但碳纳米管的顶部界面边缘处出现了明显的应力集中现象,导致此处发生断裂破坏的可能性相对较大.在拉伸载荷作用下,钛基复合材料的应力分布比较均匀,且未出现明显的应力集中现象,因而复合材料发生屈服、断裂破坏的可能性较小.当碳纳米管的相位角为15°时,复合材料发生界面脱离和基体开裂的可能性相对较小.