Purpose

The purpose of this paper is to study the Mode I fracture behavior of polycarbonate (PC) parts produced using fused deposition modeling (FDM). The focus of this study is on samples printed along the out-of-plane direction with different raster angles.

Design/methodology/approach

Tensile and Mode I fracture tests were conducted. Semi-circular bend specimens were used for the fracture tests, which were printed in four different raster patterns of (0/90), (15/−75) (30/−60) and (45/−45). Moreover, the finite element method (FEM) was used to determine the applicability of linear elastic fracture mechanics (LEFM) for the printed PC parts. The fracture toughness results, as well as the fracture path and the fracture surfaces, were studied to describe the fracture behavior of the samples.

Findings

Finite element results confirm that the use of LEFM is allowed for the tested PC samples. The fracture toughness results show that changing the direction of the printed rasters can have an effect of up to 50% on the fracture toughness of the printed parts, with the (+45/−45) and (0/90) orientations having the highest and lowest resistance to crack propagation, respectively. Moreover, except for the (0/90) orientation, the other samples have higher crack resistance compared to the bulk material. The fracture toughness of the tested PC depends more on the toughness of the printed sample, rather than its tensile strength.

Originality/value

The toughness and the energy absorption capability of the printed samples (with different raster patterns) were identified as the main properties affecting the fracture toughness of the AM PC parts. Because the fracture resistance of almost all the samples was higher than that of the base material, it is evident that by choosing the right raster patterns for 3D-printed parts, very high resistance to crack growth may be obtained. Also, using FEM and comparing the size of the plastic zones, it was concluded that, although the tensile curves show nonlinearity, LEFM is still applicable for the printed parts.

中文翻译：

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面外印刷方向熔融沉积成型聚碳酸酯零件的断裂评估——光栅角的影响

目的

本文的目的是研究使用熔融沉积建模 (FDM) 生产的聚碳酸酯 (PC) 零件的 I 型断裂行为。本研究的重点是沿平面外方向以不同光栅角度打印的样本。

设计/方法/方法

进行了拉伸和 I 型断裂试验。半圆形弯曲试样用于断裂试验，以 (0/90)、(15/-75)、(30/-60) 和 (45/-45) 四种不同的光栅图案打印。此外，有限元法 (FEM) 用于确定线弹性断裂力学 (LEFM) 对印刷 PC 零件的适用性。研究了断裂韧性结果以及断裂路径和断裂表面，以描述样品的断裂行为。

发现

有限元结果证实允许对测试的 PC 样品使用 LEFM。断裂韧性结果表明，改变打印光栅的方向可以对打印部件的断裂韧性产生高达 50% 的影响，其中 (+45/-45) 和 (0/90) 方向具有最高和最低的裂纹扩展阻力，分别。此外，除了（0/90）取向外，其他样品与块状材料相比具有更高的抗裂性。被测PC的断裂韧性更多地取决于印刷样品的韧性，而不是其抗拉强度。

原创性/价值

打印样品（具有不同光栅图案）的韧性和能量吸收能力被确定为影响 AM PC 零件断裂韧性的主要性能。由于几乎所有样品的抗断裂性都高于基材，显然通过为 3D 打印部件选择正确的光栅图案，可以获得非常高的抗裂纹扩展性。此外，使用 FEM 并比较塑性区的大小，得出的结论是，虽然拉伸曲线显示出非线性，但 LEFM 仍然适用于打印部件。