双裂纹裂尖拘束效应的表征研究

A Study on the Characterization of Crack Tip Constraint Effect from Double Cracks

为了更清晰地理解双裂纹裂尖的拘束效应,并对双裂纹裂尖拘束进行表征,本文以均质平板中非共线平行双裂纹为研究对象,对双裂纹在不同水平距离s和垂直距离h下的裂尖应力应变场进行了考察.进一步,基于统一拘束参数A_(p),通过和合并后单裂纹裂尖拘束的对比,对双裂纹裂尖拘束进行了表征.结果表明:双裂纹与合并后单裂纹裂尖的应力应变无论从分布还是大小均呈现较大的不同,若还是按照之前计算单裂纹裂尖拘束的办法仅基于双裂纹某个裂尖的应力或应变场计算双裂纹的拘束,将会得到不准确的结果.合并后单裂纹的拘束为0.10~0.30 A_总.该研究有助于理解双裂纹裂尖的拘束效应,为双裂纹裂尖拘束的表征提供了新的思路.

To gain a deeper understanding of the constraint effect from double crack tips and accurately characterize it,this study focuses on non-collinear parallel double cracks in a homogeneous plate.It examines the stress and strain fields associated with these double cracks,employing the ABAQUS finite element analysis software.Particular attention is paid to their behaviors at various horizontal distances(s)and vertical distances(h).Additionally,by leveraging the unified constraint parameter A_p,the constraints of double crack tips are compared with those of coalesced single crack tips.The findings reveal significant differences in the distributions and magnitudes of stress and strain at double crack tips compared to coalesced single crack counterparts.The conventional method of calculating the constraints from double cracks based on the stress or strain field at a crack tip,as done for single cracks,would lead to inaccurate results.Comparison of A_(total),A_(inside),and A_(outside)with A_(single)shows that considering both inside and outside crack tip strain fields aligns the variation trend of A_(total)more closely with A_(single),with a remarkably narrow fluctuation.The constraint magnitude for coalesced single cracks ranges from 0.10 to 0.30 of the total strain field(A_(total)).This approach demonstrates a degree of universality,unaffected by whether the double cracks coalesce or not.It can be directly applied to quantify the constraints imposed by double cracks,regardless of their coalescing status.This study offers valuable insights into the constraint effect of double crack tips and presents a novel method for characterizing the constraints associated with double cracks.In summary,this novel approach offers a more comprehensive and accurate understanding of the complex constraints from double cracks,providing scientific support for evaluating structural integrity with double and multiple cracks.