高分子材料非线性粘弹性问题的解法

尽管实验限制在小变形范围之内，高分子材料仍表现出明显的非线性粘弹性性能。目前由于分析上的困难，通常只好采用线粘弹性假设。基于前文，提出了一个求解高分子材料物理非线性（含线性）粘弹性问题的新原理，通过对改性聚丙烯材料的实验表明了该原理的正确性和对于此类材料的实用性。

SOLUTION APPROACH FOR NONLINEAR VISCOELASTIC PROBLEMS FOR POLYMER MATERIALS

Although the experiments are restricted to small strain, it still reveals significant nonlinear viscoelastic behavior for polymer materials. However, the assumption of linear viscoelasticity is often used because the difficulties in the analysis at present. On the bases of the previous paper, a new principle for finding solutions of physically nonlinear (or linear) viscoelastic porblems for polymers is proposed . By means of which, the solution of a nonlinear viscoelastic problem can be obtained if the corresponding nonlinear elastic problem is known. The idea of this principle is entirely different from the traditional idea for correspondence principle in linear viscoelasticity. Not the similarity between the elastic and the viscoelastic constitutive relations is utilized. Rather, the recoverability from the nonlinear viscoelastic response to the nonlinear instantaneous elastic response will be used. It is shown by the experiments for improved polypropylene that this principle is valid and is applicable for such class of materials.