高聚物长时标力学行为的预测──（VI）PMMA试样的尺寸稳定性和寿命预测值与其实测值的对比

Study on the Prediction of Long-term Mechanical Behavior of Polymers──(Ⅵ) The Comparison of the Predicted Dimensional Stability and Lifetime with It's Experimental Values for PMMA

蠕变破坏是高分子材料在工程使用中所遇到急需解决的问题，因此，从高聚物的短时标蠕变测试预测其长时标蠕变行为的研究具有重要的实际意义，文章基于前两报导出的高聚物蠕变柔量（Ｄ）同老化时间（ｔ＿α）、推迟时间系数（β）和特征时间（ｔ＿０）之间的关系式，分析了聚甲基丙烯酸甲酯（ＰＭＭＡ）的蠕变实验数据，得到了其在不同应力水平和不同老化时间的蠕变断裂寿命（ｔ＿ｆ）和力学行为（ε＿ｆ）的预测值，与其实测值符合得很好．实验证明，该方法在较大应力范围内和较宽老化时间范围内都是确切和可行的．

Failure by creep for polymeric material is a important problem to be solved in the engineering. Therefore, the study on the prediction of long term mechanical behavior and lifetime from the mcasurcmcnt or creep behavior has a great significance. A uaiversial creep function of PMMA(polymethylm eth acrylate) was derived in the plevious papes. It is succcsful in relating the compliance (D) to the aging take (t_α), the ratio of retardation bine in free and deformed state, the coefficient retardation take (β) and the intrinsic time (t_0). This relation was used to treat the creep experimental data of PMMA. The results show that the Predicted failure dimensional stability (ε_f) and lifetime (t_f) of PMMA in different stress levels and different aging take are all in an excellent agreement with those obtained directly from experiments and these methods are all reliable.