Fracture toughness measurement by cantilever bending has been widely used to study the fracture behaviour of different class of materials especially at the micro-scale. However, standard protocols of testing do not exist in these non-conventional geometries, leading to variable results. In this study we assess the geometric factors affecting the stress intensity factor solutions of a single edge notched cantilever bend specimen in different loading modes to propose suitable testing standards. Variation of stress intensity factor and mode mixity is analysed as a function of the relative position of the crack, beam cross-section, crack geometry, arm length of the cantilever and loading direction to discern the contributions of different loading states and boundary conditions on the same. During cantilever bending, state of mode I predominates for beams with length to width ratios above 4 whereas mode II and mode III predominates for shorter beams of length to width ratio of 0.5. Experimental validation is carried out both at the micro-scale and macro-scale using Barium Titanate and polymethyl methacrylate respectively.

通过悬臂弯曲测量断裂韧性已被广泛用于研究不同类别材料的断裂行为，尤其是在微观尺度上。然而，这些非常规几何结构中不存在标准测试协议，导致结果不一。在这项研究中，我们评估了影响单边缺口悬臂弯曲试样在不同加载模式下应力强度因子解的几何因素，以提出合适的测试标准。应力强度因子和模式混合的变化被分析为裂纹相对位置、梁横截面、裂纹几何形状、悬臂臂长和加载方向的函数，以识别不同加载状态和边界条件对裂纹的影响相同的。在悬臂弯曲过程中，模式 I 的状态主要用于长宽比大于 4 的光束，而模式 II 和模式 III 主要用于长宽比为 0.5 的较短光束。分别使用钛酸钡和聚甲基丙烯酸甲酯在微观尺度和宏观尺度上进行实验验证。