查询词典 microvoid

This project studies the scale-dependent deformation behavior of the metal matrix composite, the void nucleation and void growth mechanisms at the micron/submicron scale. The main results are:(1) In prophase, growth and coalescence of the void embedded in the graded matrix are analyzed in detailed;(2) Based on the infinite solid model containing a micro-void, coupling effects of the void shape and the void size on the void growth are studied carefully, the results show that it seems to exist a critical equivalent void radius, which is associated with the material length. When radius of a microvoid is close to or smaller than the critical void radius, the micro-void growth rate is essentially eliminated;(3) The coupling effects of the particle shape and size on the mesoscopic stress fields within the particle and matrix are also investigated by introducing the conception of inclusion/matrix interfacial energy. The results show that the stress concentration factors within the particle and on the matrix/particle interface are also strongly size-dependent,so the void nucleation mechanism is size-dependent.(4) By employing a specific orthogonal curve coordinate frame and a 'kernel function' conception, a 'unified method'solving the spheriodal and spherical void problems is suggested; by this unified method, size-dependent plastic potentials of the porous materials containing the spheriodal or spherical voids are obtained, which extend the traditional Gurson model for the spherical void and GLD model for the spheriodal voids to the micron scale.(5) Based on the RVE model containing the spheriodal or spherical particles, the influences of the particle shape and size on the size-dependent mechanical behavior of metal matrix composite are studied.

中文摘要：本项目对金属基复合材料在微细观尺度下的尺度相关变形行为、孔洞形核及长大的机理和模型进行了研究，取得了如下主要结果：1）在前期研究中，探讨了基体的梯度分布对孔洞长大和聚合的影响；2）基于含孔洞的无限大体模型，探讨了孔洞形状和孔洞尺寸对其长大的耦合作用，结果表明：可能存在一个与材料特征长度相关的临界孔洞尺寸，当椭球孔洞的等效半径小于临界孔洞半径时，孔洞的长大受到明显抑制；3）通过引入基体/夹杂界面能的概念，分析了夹杂尺寸、夹杂形状对材料细观应力场的耦合影响，结果表明：颗粒内部和界面上的应力集中因子强烈地依赖于夹杂的尺寸和形状，因此，孔洞的形核机理是尺寸相关的；4）采用一种特殊的正交曲线坐标系和引入"核函数"的概念，"统一"地得到了含椭球和球形孔洞的材料的尺寸相关塑性势，它将传统的Gurson球形孔洞模型和GLD椭球孔洞模型推广到微尺度范围；5）基于含椭球和球形夹杂的体胞模型，初步研究了夹杂形状、夹杂尺寸对金属基复合材料尺寸相关力学行为的影响。

The gel dynamics experiments showed that the gel formation law was similar with the other polymer systems, which wasrelated with dense surface under the soft coagulating condition and the thickening gel; the square of gel thickness was linear with coagulation time. The qualitative analysis of the surface puckers of fibers spun from wet spinning and dry-jet wet spinning was made. The positions where the die swell appeared were not the same and the die swell appeared at the air gap where the fiber would markedly been elongated and vary little in the coagulant, thus the surface of fiber spun from dry-jet wet spinning was more smooth. The radial component concentration gradient was responsible for the radial structure of PAN fiber spun from dry-jet wet spinning. The thicker surface with microvoid structure of

对湿纺和干湿纺进行比较表层沟槽的产生进行定性分析，原因在于孔口胀大区域出现在不同位置，在干湿纺中，溶液的孔口胀大出现在空气层，并在该区完成大部分形变，进入凝固浴后形变很小，纤维表面较为光滑；干湿纺PAN纤维径向结构存在差异，这与丝条内组分由于双扩散进行导致径向上存在浓度差异直接相关；凝固强度较大的体系，可以获得厚度较大且孔结构尺寸较小的皮层；含较少缠结的PAN原液在纤维成形后截面很圆整，但原液缠结浓度增大时成形后圆整度下降；PAN纤维成形是一个远离平衡的过程，凝固作用缓和的体系可以使成形过程靠近平衡，可获得更大尺寸的孔洞结构；原液中少量的非溶剂添加剂显著改变纤维径向结构，可获得孔洞尺寸更小和更为均一的径向结构，这与径向浓度差异的减小、分相时间的集中相关；PAN原液的成形纤维表面依赖于凝固强度；由AFM对相近凝固条件下成形的PAN膜进下

It was found experimentally that HIC happens via nonacid nucleation and then quasi-cleavage along {111} planes when C〓 is higher. Otherwise, in the case of lower C〓, hydrogen enhances ductile fracture via hydrogen-enhancing microvoid nucleation, growth and connection.

对预充氢的310钢薄膜进行TEM原位拉伸表明，当氢浓度较高时，氢致断裂通过空洞形核，然后沿{111}面准解理扩展的方式进行；当氢浓度较低时，氢促进纳米空洞形核、长大和连通，进而导致韧断。

SEM analysis finds that the fractures are intercrystalline plus quasi-cleavage fractures under quasi-motionless state;with the increase of stress intensity factor,fractureschange from transcrystalline quasieleavage fractutes to microvoid-coalescence dimple plus cleavage frac-tures,The increase of fracture toughHess of 8090Al-Li alloy under high stress intensity factor is associ-ated with the deformation mechanism and the change of precipitation Free Zone of grain boundary.

扫描电镜分析发现，准静态下的断裂为沿晶和准解理混合断口；随着应力强度因于的增加，断裂从准解理断裂过渡到准解理和显微空穴聚集的韧窝断裂舶混合断口。高应力强度因于率下断裂韧度的提高与其变形机制和晶界无沉淀区的变化有关。

With increasing the hydrogen content, HIC appears firstly as ductile cracking by microvoid coalescence, then embrittled cracking by microvoid coalescence and finally by low energy rapid cleavage brittle cracking.

随氢含量的增加，相继表现出微孔聚合式韧性开裂、脆化的微孔聚合式开裂和低能解理式脆性开裂。

Neither the killing of Mr Zarqawi nor any breakthrough on the political front will stop the insurgency and the fratricidal murders in their tracks.

在对危险的南部地区访问时，他斥责什叶派民兵领导人对中央集权的挑衅行为。

In fact,I've got him on the satellite mobile right now.

实际上 我们已接通卫星可视电话了