焦散线法在聚合物共混体系断裂问题中的应用.pdfVIP

焦散线法在聚合物共混体系 断裂问题中的应用 徐杰， 励争， 王君， 傅缤 （北京大学力学与工程科学系，北京 100871 ） 摘要: 本文研究了高聚物共混物HDPE/POE-g-MA/CaCO3 三元共混体系的常规、蠕变和断裂 力学性能，分析了材料常规性能参数随填充物含量增加的变化趋势，发现填充相和界面相的 比重对于材料的力学行为特征有明显的影响。焦散线法被应用于研究材料的静态断裂性能， 测定了I 型裂纹尖端的应力强度因子，并在实验结果的处理中考虑了由材料的粘弹性造成的 时间相依性。基于电镜对含I 型裂纹的蠕变试样的裂纹尖端细观形貌观测，针对材料断裂破 坏的细观机理和增韧效果作出了讨论。本文的实验和分析结果对促进高聚物复合材料的进一 步实验研究和细观设计具有实用价值。 关键词: 高聚物共混物；粘弹性；应力强度因子；焦散线；细观观测 Experimental studies on fracture problems of viscoelastic * polymer blends by the method of caustics Xu Jie, Li Zheng, Wang Jun, Fu Bin （Department of Mechanics and Engineering Science, Peking University, Beijing, 100871 ） Abstract: The general, creep and failure mechanical properties of viscoelastic ternary polymer blends HDPE/POE-g-MA/CaCO3, different in component ratio, are studied by electromotive experiments in this paper. The variation of material parameters along with the filling ratio is analyzed. The filling ratio and the existence of interface phase are found to be vital factors to the mechanical performance of the materials. Then the method of static caustics is applied to fracture problems of thin plates with single edge crack of mode I. A series of caustic images surrounding the specimen crack tip are obtained, thus recording the development of stress intensity factor K Ι with time in a long term. In the calculation of K , the material viscoelasticity is taken into Ι consideration. In addition, mesoscopic observation around the crack tip of long time loaded fracture specimens is achieved by SEM and discussion on mechanism of material destruc