聚苯乙烯断面形貌特征参量对断裂能耗的影响

对缺口聚苯乙烯试样进行了不同加载速率下的三点弯曲实验，通过对加载速率、断面特征区特征参量、断裂能耗三者间关系的分析，指出断裂表面特征形貌中的镜面区、肋状区的形成是能量消耗的主要过程．实验结果表明，随着加载速率增大，镜面区尺寸增大并逐渐趋于平缓，肋条宽度减小而肋区粗糙度增大．断裂能耗与加载速率间存在极小值现象，该极小值出现在２５ｍ／ｍｉｎ的加载速率下，与断面形貌特征的变化正好对应；加载速率＜２５ｍ／ｍｉｎ时，断面主要由镜面区、最后断裂区组成，断裂能耗的变化取决于镜面区尺寸的变化；加载速率＞２５ｍ／ｍｉｎ时，断面由镜面区、肋区、最后断裂区组成，断裂能耗的变化主要和肋区粗糙度的变化有关．

THE INFLUENCE OF THE FRACTURE MORPHOLOGICAL PARAMETERS ON BENDING BREAK ENERGY OF POLYSTYRENE

The PS specimens were subjected to three point bending under different loading rate.Through the analysis of experimental results,the forming process of the mirror zone and the rib zone is the principal process of energy consumption.With the increase of loading rate,the size of mirror zone decreases and tends towards constant progressively.At the same time,the rib width decreases while the roughness of rib zone increases.A minimum appearing at the loading rate 2 5m/min exists in the relationships between energy consumption and loading rate.When loading rate below 2.5m/min,the fracture surfaces were chiefly made up by the mirror zone and the last fracture zone.The change of break energy is mainly decided by the change of the size of mirror zone.When the loading rate beyond 2.5m/min,the fracture surfaces were composed of the mirror zone,the rib zone and the last fracture zone.The change of energy consumption is primarily decided by the roughness of rib zone.