Void Growth in Glassy Polymers: Effect of Yield Properties on Hydrostatic Expansion
Void Growth in Glassy Polymers: Effect of Yield Properties on Hydrostatic Expansion
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玻璃状聚合物中的空洞增长：屈服特性对静水膨胀的影响
DOI：
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发表时间：
1997
期刊：
影响因子：
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通讯作者：
V. Giessen
中科院分区：
文献类型：
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作者：
A. Steenbrink;V. Giessen
用简单的球对称模型研究了塑性变形玻璃聚合物中的空洞生长。这种类型的空穴生长发生在空化的聚合物-橡胶共混物中，并且在较小的范围内发生在裂纹萌生期间。该研究提供了静水加载条件下弹粘塑性空隙生长所需应力的近似值。本构模型考虑了速率和温度相关的屈服、屈服后的本征应变软化以及大变形时分子取向导致的后续硬化等特征。研究了这些特征对孔隙膨胀和应力分布的单独影响。由于大多数玻璃状聚合物在屈服时具有较大的应变，因此即使在宏观屈服时，弹性效应也起着重要作用。因此，对最大应力的预测明显低于基于刚塑性行为的预测，特别是对于低空隙体积分数。
Void growth in plastically deforming glassy polymers is investigated by means of a simple spherical symmetric model. This type of void growth occurs in cavitated polymer-rubber blends and, at a smaller scale, during craze initiation. The study serves to provide approximate values for the stresses required for elastic-viscoplastic void growth under hydrostatic loading conditions. The constitutive model accounts for features such as rate and temperature dependent yield, intrinsic strain softening after yield, and subsequent hardening due to molecular alignment at large deformations. The separate effects of these features on void expansion and the stress distribution are studied. Due to the relatively large strain at yield for most glassy polymers, elastic effects play an important role even at macroscopic yield. Therefore, predictions of the maximum stress are significantly lower than those based on rigid-plastic behaviour, especially for low void volume fractions.