基于三维裂纹尖端应力场的应力强度因子计算方法

发布时间：2018-03-10 07:23

本文选题：三维裂纹　切入点：裂纹尖端应力场　出处：《航空动力学报》2016年06期 　论文类型：期刊论文

【摘要】：提出一种基于无限大体裂纹尖端弹性应力场理论解的前几项多项式函数,对实际裂纹体弹性应力场有限元解进行拟合来计算应力强度因子的方法.该方法在计算应力强度因子时不需要预先假设裂纹尖端的应力应变状态,应力强度因子计算结果更符合三维裂纹体裂纹尖端实际的应力应变状态.首先基于二维无限大板中心穿透裂纹应力场理论解验证了方法的有效性,探讨了拟合确定应力强度因子需要的多项式应力函数的项数.然后分别以二维大板中心穿透裂纹、三维大体内埋圆裂纹和三维有限厚板中心穿透裂纹的应力强度因子计算为例,通过与无限大板和无限大体应力强度因子理论解以及基于位移外推法和1/4节点张开位移法的应力强度因子有限元解的对比分析,验证了该方法的有效性和合理性.研究表明该方法能够合理反映三维裂纹体裂纹尖端的实际应力应变状态,计算得到的应力强度因子数值更合理.
[Abstract]:A first polynomial function based on the theoretical solution of elastic stress field at the tip of an infinite crack is proposed. The stress intensity factor is calculated by fitting the finite element solution of the elastic stress field of the actual crack body, which does not require the presupposition of the stress and strain state at the crack tip in the calculation of the stress intensity factor. The calculated results of stress intensity factor are more consistent with the actual stress and strain state at the crack tip of a three-dimensional cracked body. Firstly, the validity of the method is verified based on the theoretical solution of the stress field of a two-dimensional infinite plate with a central penetrating crack. The term number of polynomial stress function for fitting stress intensity factor is discussed, and then the calculation of stress intensity factor for two dimensional large plate center penetrating crack, three dimensional large body buried circle crack and three dimensional finite thickness plate center penetrating crack is taken as an example. The finite element solution of stress intensity factor based on displacement extrapolation method and 1/4 node opening displacement method is compared with the theoretical solution of infinite plate and infinite general stress intensity factor, and the finite element solution of stress intensity factor based on displacement extrapolation method and 1/4 node opening displacement method. The validity and rationality of the method are verified. The results show that the method can reasonably reflect the actual stress-strain state at the crack tip of a three-dimensional cracked body, and the calculated values of the stress intensity factor are more reasonable.
【作者单位】：南京航空航天大学能源与动力学院江苏省航空动力系统重点实验室;南京航空航天大学机械结构力学及控制国家重点实验室;
【分类号】：V231.91

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