剪切带状分叉的力学条件

在已论证过的应变软化效应对形成剪切带状分叉的作用的基础上,本文研究了:(1)什么受力情况最易激发剪切带(2)采用什么力学模型和参数可以模拟材料中的曲线型带状分叉

表层弥散预应变硬化对薄钢板变形局部化的影响

试验研究了具有一定形貌及粗糙度的激光毛面薄钢板及同材质普通薄钢板的失稳行为。结果表明激光毛面薄钢板变形局部化过程明显滞后于普通板，其表层弥散分布的预应变硬化点在稳定薄板变形、延缓变形局部化过程中起到重要作用

血清一阶导数荧光光谱诊断早期恶性肿瘤

利用Wistar大鼠接种恶性肉瘤模拟人患上癌症。取Wistar大鼠眼静脉血制备血清,并用乙醇简单处理得上层清液,扫描获得其一阶导数荧光光谱,确定上层清液原卟啉发射带(630 nm附近)的峰高,观察到健康Wistar大鼠与癌变大鼠的血清样存在明显差异,10例癌变样假阳性率为0,而20例正常样中仅有1例假阳性达到了恶性肿瘤早期诊断的目的

低碳钢的大应变低周疲劳

对三种低碳钢的不同缺口的轴对称圆柱形试样在大应变循环下的低周疲劳行为进行了研究。以考察失效周次在１００次以内的疲劳断裂行为。结果表明随着被控循环应变幅度的增大，低碳钢的低周疲劳寿命降低，断裂模式则由疲劳解理逐渐向延性韧窝过渡。缺口处的三向应力程度以及起始循环加载的静态损伤都对最终的疲劳失效有重要的影响。建议采用一种广义的循环应变参量上来概括影响这种大应变低周疲劳的诸因素，从而可以采用修正的Ｃｏｆｆｉｎ－Ｍａｎｓｏｎ关系式描述其疲劳行为

Notch 和Wnt信号通路及两者的交叉串话与乳腺癌发生、发展的关系

乳腺癌是全球女性最常见的恶性肿瘤,而且是女性癌症死亡的最主要原因。对于乳腺癌的发病机制,目前尚不清楚。Notch和Wnt信号通路在多细胞生物的生长、发育及肿瘤形成中起着至关重要的作用,两者之间存在着直接或间接的串话。笔者就这2条信号通路在乳腺肿瘤的发生、发展过程中所表现出来的相互协同作用进行综述。国家自然科学基金重大国际(地区)合作研究项目(81320108015

Plane strain asymptotic fields for cracks terminating at the interface between elastic and pressure-sensitive dilatant materials

The plane strain asymptotic fields for cracks terminating at the interface between elastic and pressure-sensitive dilatant material are investigated in this paper. Applying the stress-strain relation for the pressure-sensitive dilatant material, we have obtained an exact asymptotic solution for the plane strain tip fields for two types of cracks, one of which lies in the pressure-sensitive dilatant material and the other in the elastic material and their tips touch both the bimaterial interface. In cases, numerical results show that the singularity and the angular variations of the fields obtained depend on the material hardening exponent n, the pressure sensitivity parameter mu and geometrical parameter lambda

Formation of shear bands in plane sheet

The formation of shear bands in plane sheet is studied, both analytically and experimentally, to enhance the fundamental understanding of this phenomenon and to develop a capability for predicting material failure. The evolution of voids is measured and its interaction with the process of shear banding is examined. The evolving dilatancy in plasticity is shown to have a vital role in analysing the shear-band type of bifurcation, and tremendously reduces the theoretical value of critical stresses. The analyses, referring to both localized and diffuse modes of bifurcation, fairly explain the corresponding observations obtained through testing a dual-phase steer sheet and provide a justification of the constitutive model used

韧性材料的剪切带状分叉

本文从两个位移变量入手分析了平面应变条件下的剪切带状分叉从而放弃了分叉时体积不变的约束。文中论证了分叉时材料将伴随有局部性的体积变化,应变软化,即材料性质的分叉突变。文中还用摄动法近似分析了材料缺陷可能造成的影响