Defect-mediated creep of structured materials
Defect-mediated creep of structured materials
复制标题
结构材料的缺陷介导蠕变
DOI：
10.1209/epl/i2001-00305-x
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发表时间：
2001
期刊：
影响因子：
--
通讯作者：
C. Ober
中科院分区：
文献类型：
--
作者：
R. Colby;L. Nentwich;Scott R. Clingman;C. Ober
低应力蠕变实验表明，液晶聚合物是一种粘弹性固体，其模量为100达因/cm ~ 2，屈服应力为50达因/cm ~ 2。近晶和向列晶在非常低的应力水平下都是粘弹性固体，其模量与它们的缺陷织构有关。在应力水平略高于屈服应力时，存在一个屈服区，其中变形速率和缺陷间距在所施加的应力中为幂律。我们利用很久以前奥罗万关于晶体中线缺陷运动的思想来理解这些幂律。这些幂律的指数对于向列相和近晶相是不同的，但是超塑性普适性类似乎也适用于超塑性金属和陶瓷。
Low-stress creep measurements on a nematic liquid crystal polymer indicate that it is a viscoelastic solid, with a modulus of 100dynes/cm2 and a yield stress of 50dynes/cm2. Both smectics and nematics are viscoelastic solids at very low stress levels, with a modulus that is related to their defect texture. At stress levels somewhat above the yield stress, there is a yielding regime where the deformation rate and defect spacing are power laws in the applied stress. We understand these power laws using the ideas developed long ago by Orowan for the motion of line defects in crystalline solids. The exponents of these power laws are different for nematics and smectics, but the nematic universality class also appears to apply to superplastic metals and ceramics.