By means of controlling the macrocopic stress triaxiality of the cell,the FE simulation analyses have been carried on the coalescencemechanism of voids with different shape. The results show: (1)nearing and transeveral growth of neighboring voids are two kinds ofbasic mechanism of void coalescence , and they have different effects underdifferent stress triaxiality level, and there is an obviouser transferbetween the two kinds of mechanism when stress triaxiality R is1.25 or so. (2) the critical void volume fraction fC isn't a materialconstant , so it can't be used as material failure criterion. (3) thevoid shape is an important microscopic structure parameter which caneffect void coalescence clearly when stress triaxiality level is lower,but the void coalescence isn't too sensitive to its shape under higherstress traixiality lever. Based on these, in the present paper, theauthors present a new effective energy criterionMWV=(W0V)C. Compared with otherold model, the new model can response the comprehensive use of shapework and volume work to the void coalescence, and this new model hasobvious physical background. The calculations show also that it candescribe reasonably the transveral coalescence of neighboring voids indifferent triaxial stress fields.%通过体胞分析方法,对不同形状孔洞在从光滑试样到裂纹试样的三轴应力场中的聚合机理进行了较精确的有限元分析,计算结果表明:(1)孔洞的相互靠近和横向扩展是导致相邻孔洞发生内颈缩聚合的两种基本机制,在应力三维度R等于1.25附近,这两种机制发生较明显的变化;(2)单纯以孔洞体积分数fC概念为基础的材料破坏参数一般敏感于应力三维度,不能很好地预报不同三轴应力场中材料的破坏.在此基础上,提出了描述孔洞聚合的有效能量MWV,建立了一个新的具有明确物理意义,不敏感于应力三维度的孔洞聚合判据MW=(W0V)C,与现有准则比较,该准则能反映材料破坏对形状改变和体积改变的综合抗力,并能更好地刻画不同三轴应力场中孔洞的横向聚合.
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