Abstract Mechanical components produced by the 3D-printing technique contain small voids by nature, which make them susceptible to fracture. Therefore, understanding the fracture behavior of these components improves the applicability of this manufacturing method. In this study, the effect of layer orientation is investigated on the mixed-mode I/II fracture behavior of additively manufactured poly-carbonate produced using a fused deposition modelling (FDM) printer. A total of 48 semi-circular bend (SCB) specimens with different mode mixities and printing orientations are tested. The curves for the maximum tangential stress (MTS) and the generalized MTS (GMTS) criteria are then produced using the mode I fracture properties for the weakest and the strongest direction of the printed material. This results in two failure curves for each of the criteria. Comparing the mixed-mode fracture toughness data with these curves, it is observed that all the data are placed between the two GMTS curves (regarding error bands). As an engineering approach, the band created by the GMTS curves, called the GMTS range, is suggested as an acceptable band for use in engineering designs. Furthermore, in a more detailed analysis, the fracture paths of the specimens are correlated with the position of the experimental data in the GMTS range. Three different fracture modes occur during the tests depending on the layer orientation and mode mixity of the sample. The inter-layer and the cross-layer modes correspond to the data points on the lower and upper fracture curves, while the data points in the middle represent the samples undergoing the crack multi-kinking mode.

中文翻译：

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面内层取向对 3D 打印聚碳酸酯试样混合模式 I-II 断裂行为的影响

摘要 3D 打印技术生产的机械部件本质上含有小空隙，这使得它们容易断裂。因此，了解这些部件的断裂行为可以提高这种制造方法的适用性。在这项研究中，研究了层取向对使用熔融沉积建模 (FDM) 打印机生产的增材制造聚碳酸酯的混合模式 I/II 断裂行为的影响。总共测试了 48 个具有不同模式混合和印刷方向的半圆弯曲 (SCB) 样品。最大切向应力 (MTS) 和广义 MTS (GMTS) 标准的曲线然后使用打印材料最弱和最强方向的 I 型断裂特性生成。这导致每个标准的两条失效曲线。将混合模式断裂韧性数据与这些曲线进行比较，可以看出所有数据都位于两条 GMTS 曲线之间（关于误差带）。作为一种工程方法，由 GMTS 曲线创建的频带称为 GMTS 范围，建议作为工程设计中使用的可接受频带。此外，在更详细的分析中，试样的断裂路径与实验数据在 GMTS 范围内的位置相关。根据样品的层取向和模式混合，在测试过程中会出现三种不同的断裂模式。层间和跨层模式对应于上下裂缝曲线上的数据点，