Abstract The influence of five different types of morphological imperfection – curved cell wall, corrugation, cell shape irregularity, missing cell walls and non-uniform distribution of cell wall thickness – on steady state creep of closed-cell aluminum foams is systematically studied under uniaxial compressive loading. A refined theoretical model is developed to predict the steady state creep rate of idealized tetrakaidecahedral (TKD) closed-cell foams. Based upon the TKD model, finite element modeling is also carried out. The presence of imperfections usually leads to significant increase in steady state creep rate. The creep rate increases linearly with the degree of cell shape irregularity and the curvature of curved cell walls, while increases as a power law function of the area fraction of missing cell walls and the dispersion degree of non-uniform distributed cell wall thickness. The combined effect of three different random defects—cell shape irregularity, missing cell walls and non-uniform distribution of cell wall thickness—causes more drastic increase in creep rate than any single or dual imperfections. Interactions among the three are small and can be neglected. Finally, an empirical formula of steady state creep rate is proposed to give a good prediction for closed-cell foams with random imperfections.

中文翻译：

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闭孔泡沫铝的蠕变：缺陷和预测建模的影响

摘要 系统研究了五种不同类型的形态缺陷——弯曲泡壁、波纹、泡孔形状不规则、缺孔壁和泡孔壁厚度分布不均——对闭孔泡沫铝在单轴压缩下稳态蠕变的影响。加载。开发了一种改进的理论模型来预测理想化四面体 (TKD) 闭孔泡沫的稳态蠕变速率。在TKD模型的基础上，还进行了有限元建模。缺陷的存在通常会导致稳态蠕变速率显着增加。蠕变速率随着细胞形状不规则程度和弯曲细胞壁的曲率线性增加，而随着缺失细胞壁面积分数和非均匀分布细胞壁厚度的分散程度的幂律函数而增加。三种不同的随机缺陷——细胞形状不规则、细胞壁缺失和细胞壁厚度分布不均——的综合影响导致蠕变速率的增加比任何单一或双重缺陷都大。三者之间的相互作用很小，可以忽略不计。最后，提出了稳态蠕变速率的经验公式，以对具有随机缺陷的闭孔泡沫进行良好的预测。缺少细胞壁和细胞壁厚度分布不均匀——比任何单一或双重缺陷导致蠕变速率的急剧增加。三者之间的相互作用很小，可以忽略不计。最后，提出了稳态蠕变速率的经验公式，以对具有随机缺陷的闭孔泡沫进行良好的预测。缺少细胞壁和细胞壁厚度分布不均匀——比任何单一或双重缺陷导致蠕变速率的急剧增加。三者之间的相互作用很小，可以忽略不计。最后，提出了稳态蠕变速率的经验公式，以对具有随机缺陷的闭孔泡沫进行良好的预测。