【目的】研究初始缺口大小对裂纹起裂的影响。【方法】采用晶体相场(phase-field-crystaUPFC)模型研究单轴拉伸应力作用下,材料裂纹起裂的动态演化过程,并结合自由能分析裂纹起裂与扩展过程中,不同缺口尺寸对裂纹起裂的影响。【结果】沿:c方向施加恒应变,初始缺口:y方向尺寸较小时,改变缺口:c方向尺寸,缺口并不起裂;当3;方向尺寸达到一定值时,初始缺口会起裂。当:V方向尺寸接近起裂临界值时,:c方向尺寸的增大会延缓缺口的起裂。当:r方向尺寸改变量较小时,裂纹并不起裂,当增大到x方向尺寸临界值时,缺口开始起裂并扩展。【结论】在应力大小一定的情况下,缺口起裂与应力作用方向垂直的缺口尺寸密切相关,只有与应变作用方向垂直的尺寸达到临界值,缺口才会发生起裂。
【Objective】T o study the effect of initial crack size o n crack initiation.【Methods】T h ed y n a m i c of process crack propagation un d e r the uni-axial tension deformation in single crystalsis simulated b y the p h a s e-field-crystal(P F C)m o d e l.T h e free energy is used to analyze the influenceof different initial crack size o n the crack initiation in the process of crack initiation a n dcrack propagation.[R e s u l t s l W h e n the initial crack of y direction size is smaller,there is no initiationof crack un d e r the uniaxial tension in the x axis?although the notch size in x directionc h a n g e s,w h e n the y direction size reaches a certain value?the initial cracks will e x p a n d.T h etime of crack initiation is delayed with the increase of x direction size.W h e n the initial crack ofx direction size changes less?there is no initiation of crack?a n d the initial cracks will e x p a n dw h e n the x direction size reaches a certain value.【Conclusioit】T h e initiation of crack is closelyrelated to the crack size of vertical stress direction.T h e crack extension occurs?if only the sizeof notch reaches a certain value.