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摘要: 本文从文献[1]中用于分析柱壳动态膨胀断裂过程的损伤度函数出发，将它推广到对一维应变下层裂过程的数值模拟研究。试件材料为LY-12铝，其特性方程取为含粘性的本构方程形式。数值计算结果很好地再现了实测自由面速度ufs随时间t的变化过程，并表现出层裂强度c及层裂面上的临界损伤度c都分别是应变率c'的单调递增函数关系。c~c'的这种变化规律在许多文献中已屡见报道，例如可见文献[2-3]。在105 s-1~106 s-1应变率范围内，c~c'关系可以表示为c'exp(-11.4c)=2 100 s-1，这个式子可以作为一种层裂判据使用。数值计算还给出了层裂片的损伤度剖面，其形状特征与Barbee等对回收试件的细观测量结果在定性上一致。Abstract: In Ref.[1], a damage-level function is proposed for analyzing the dynamic fracture processes of expanding cylindrical shell. In this paper, we extend the model to the case of planar geometry and perform numerical simulation for the dynamic damage processes under uniaxial strain case. The studied material is LY-12 aluminum and a kind of constitutive equation with viscous effect is utilized. The calculated free-surface velocity versue time relation is consistent with the experimental results. The calculated results also indicate that the spall strength c and the critical damage-level at fracture plane, c, are both monotone increase function of strain rate c', respectively. This kind of c~c' relation has been reported in many other articles, for example in Ref.[2-3]. The relation c~c' can be expressed as c'exp(-11.4c)=2 100 s-1 in the strain -rate range from 105 s-1 to 106 s-1. We think this expression could be used as a kind of spall criterion. The damage-level profiles in the spalled layer are also given from the numerical results, and the specific feature of the profiles is qualitatively in accord with that of the micro-photographic results from recovery specimens reported by Barbee, et al.
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Key words:
- spall criterion /
- damage-level function /
- numerical simulation /
- strain rate /
- LY-12 aluminum
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