Extensibility of rubber under different types of deformation
Extensibility of rubber under different types of deformation
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DOI：
10.1122/1.1835343
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发表时间：
2005-01-01
影响因子：
3.3
通讯作者：
Gent, AN
中科院分区：
文献类型：
--
作者：
Gent, AN
交联橡胶网络中分子链的有限长度对延伸性造成了限制，因为一些分子链变得完全拉伸。在建立应变能函数W以描述橡胶的弹性响应时必须考虑这一特性，特别是在高应变情况下。问题是：不同变形类型的最大应变是相同的，还是不同的？这里比较了不同类型的均匀变形的最大应变：简单拉伸；简单剪切和纯剪切(约束拉伸)；以及等轴拉伸。假设橡胶是由高斯股组成的网络，这些高斯股在无应变状态下随机排列，并以第一应变不变量J(1)的极限值J(1m)进行仿射变形，直到代表性的股变得完全拉伸。Dickie和Smith(1971)指出，等轴拉伸时的延伸率仅为简单拉伸时的70%左右，符合J(1)的极限值。对于其他简单类型的变形，延伸率预计几乎相等。然后考虑了模型和实验中可能存在的缺陷。得出的结论是，一般的结果可能是有效的，橡胶大应变弹性模型应包括第一应变不变量J(1)的极限值，而不是第二应变不变量J(2)的极限值。(C)2005年流变学学会。
The finite lengths of molecular strands in a crosslinked rubber network impose a limit on the extensibility because some of the strands become fully stretched. This feature must be taken into account in formulating a strain energy function W to describe the elastic response of rubber, especially for high strains. The question is: Are the maximum strains the same for different types of deformation, or different? Maximum strains are compared here for various types of homogeneous deformation: simple extension; simple shear and pure shear (constrained tension); and equibiaxial extension. The rubber is assumed to consist of a network of Gaussian strands that are randomly arranged in the unstrained state and deform affinely until representative strands become fully stretched, at a limiting value J(1m) of the first strain invariant, J(1). Dickie and Smith (1971) showed that the extensibility in equibiaxial stretching is only about 70% of that in simple extension, in accord with a limiting value of J(1). For other simple types of deformation the extensibilities are expected to be nearly equal. Possible deficiencies in the model and in the experiments are then considered. It is concluded that the general result is likely to be valid, and that a model for rubber elasticity at large strains should include a limiting value of the first strain invariant, J(1), rather than the second, J(2). (C) 2005 The Society of Rheology.