In brittle materials, the material-related “mirror constant” correlates the length of the mirror radius measured on the fractured surfaces with the fracture strength. The mirror constant is traditionally estimated visually following ASTM Standard C1678 guidelines. Some bias is inevitably introduced due to different imaging tools/methods, magnifications, and observers’ interpretation of fractographic features. Quantitative characterization of these uncertainties is not well understood and remains a challenge. In this study, thirty-one aluminosilicate glass plates were fractured by 4-points bending and twelve observers independently measured the mirror constant using various imaging methods and magnifications. A systematic study to determine the source of bias was conducted with design of experiment analyses and pairwise T-tests for statistical interpretations. It was found that the uncertainty introduced by observers was 1.5 times the one introduced by the imaging methods considered, and 3 times the effect of magnifications for optical microscopy.

在脆性材料中，与材料相关的“镜常数”将在断裂表面上测量的镜半径与断裂强度相关联。传统上，镜面常数是根据ASTM标准C1678准则目视估算的。由于成像工具/方法，放大率和观察者对分形特征的解释不同，不可避免地会引入一些偏差。这些不确定性的定量表征尚不为人所知，仍然是一个挑战。在这项研究中，通过四点弯曲使三十一个铝硅酸盐玻璃板破裂，十二名观察者使用各种成像方法和放大倍率独立地测量了镜常数。通过设计实验分析和成对T进行了系统的研究以确定偏倚的来源-统计解释测试。发现观察者引入的不确定度是所考虑的成像方法引入的不确定度的1.5倍，是光学显微镜放大倍率的3倍。