复合型疲劳裂纹的扩展

1.引言实际工程中,对于结构部件的寿命需要作出理论上的估计,因此部件在疲劳载荷作用下裂纹的扩展是一个重要的研究课题。一个疲劳裂纹的扩展将取决于部件所用材料的性质、几何形状以及受载情况等等因素,也就是说需要用断裂力学的理论来解决结构部件的设计与分析。过去一般对于疲劳裂纹的扩展主要基于P.C.Paris公式,即     

复合型断裂应变准则

根据裂纹通常沿径向扩展这一基本事实和文献[1]的思想,以垂直于径向的平面上的主应变ε_1为参量,在等能量密度面上(全复合型脆断情形)或在等形变能密度面上(全复合型小范围屈服情形)提出:1)ε_1的最大值方向为裂纹分枝扩展方向;2)当lim2r~(1/2)(ε_1)_(max)达到临界值时,裂纹就起始扩展(全复合型脆断情形);3)当2r_ρ(ε_1)_(max)达到临界值时,裂纹就开始扩展(全复合型小范围屈服情形).1.全复合型脆断平面穿透裂纹在Ⅰ、Ⅱ、Ⅲ型全复合加载下,裂纹尖端位移场为     

ON THE CORRECTION BY MCCLINTOCK AND IRWIN

In the case of quasi-brittle fracture,at the crack tip there is a small plastic regionwhose affection cannot be neglected.There fore the lnear elastic asympototu fields must becorrected.In 1965 F.A.McClintock and G.R.Irwin Presented a correction which sincethen has been adopted extensively.Here in this paper.n must be pointed out that suchcorrection is wrong.A correct result is given.     

二维升力体的非线性振动

本文给出了二维升力体非线性振动的解析解答。     

K-S模型中孤子解及尺寸效应

本文给出φ⁴方程的另一个非拓扑性孤子型解,并且在K-S模型中,讨论其尺寸效应及其有关的问题。 关键词：     

On the correction by McClintock and Irwin

In the case of quasi-brittle fracture, at the crack tip there is a small plastic region whose affection cannot be neglected. Therefore the linear elastic asympototic fields must be corrected. In 1965 F. A. McClintock and G. R. Irwin presented a correction which since then has been adopted extensively. Here in this paper, it must be pointed out that such correction is wrong. A correct result is given.Communicated by Chien Wei-zang.     

Nonlinear oscillation of a two-dimensional lift body

It is very difficult to obtain an exact analytical solution to a nonlinear ordinary differential equation, so till now analytical solutions are rare in this area. The author has obtained the exact analytical solutions of this type of nonlinear oscillations. In this paper as an example, the exact analytical solution of nonlinear oscillation of a two-dimen-sional lift body, which has attracted the attention of research workers for a long time, is given.     

方程u_(tt)-cu_(xx)+au+bu~3=0的解析解答

本文给出了方程u_(tt)-cu_(xx)+au+bu~3=0的一个解析解系.     

NONLINEAR OSCILLATION OF A TWO-DIMENSIONAL LIFT BODY

It is very difficult to obtain an exact analytical solution to a nonlinear ordinarydifferential equation,so till now analytical solutions are rare in this area.The author hasobtained the exact analytical solutions of this type of nonlinear oscillations.In this paper asan example,the exact analytical solution of nonlinear oscillation of a two-dimen-sional liftbody,which has attracted the attention of research workers for a long time,is given.     

关于McClintock和Irwin修正

在准脆断情形中,裂纹尖端存在一个微小塑性区.这一塑性区虽然微小.但其影响又不能忽略,因此需要对原有的线弹性渐近场进行校正.F.A.McClintock和G.R.Irwin[1]于1965年提出了一个修正理论,并被广泛引用至今.本文指出这一修正结果是错误的,并给出了正确的修正结果.