Cai Naijia, Meng Qiaoyu, Zhang Keqiang, Geng Luchao, He Rujie, Qu Zhaoliang
Institute of Advanced Structure Technology, Beijing Institute of Technology, Beijing 100081, China.
College of Engineering, Peking University, Beijing 100871, China.
Materials (Basel). 2022 Mar 30;15(7):2547. doi: 10.3390/ma15072547.
The additive manufacturing process may create flaws inside ceramic materials. The flaws have a significant influence on the macroscopic mechanical behavior of ceramic materials. In order to reveal the influence of flaws on the mechanical behavior of additively manufactured ceramic, flaw evolution under mechanical loads was studied by in situ X-ray computed tomography (XCT) in this work. In situ compression XCT tests were conducted on stereolithographic additively manufactured AlO ceramic. The three-dimensional full-field morphologies at different compressive loads were obtained. The evolution of flaws, including pores, transverse cracks, and vertical cracks, during compressive loading was observed. The number and volume of pores, transverse cracks, and vertical cracks were extracted. It was found that most pores and transverse cracks tend to be compacted. However, high compressive loads cause vertical cracks near the upper surface to expand, leading to the failure of the specimen. Real flaws with morphological and positional information were introduced into the finite element models. The influence of different types of flaws on the mechanical behavior is discussed. It was found that vertical cracks have a greater influence on mechanical behavior than do transverse cracks under compression. The presence of transverse cracks contributes to the evolution of vertical cracks. This study may be helpful for process optimization and performance enhancement of additively manufactured ceramic materials.
增材制造过程可能会在陶瓷材料内部产生缺陷。这些缺陷对陶瓷材料的宏观力学行为有重大影响。为了揭示缺陷对增材制造陶瓷力学行为的影响，本文通过原位X射线计算机断层扫描（XCT）研究了机械载荷下的缺陷演变。对立体光刻增材制造的AlO陶瓷进行了原位压缩XCT试验。获得了不同压缩载荷下的三维全场形态。观察了压缩加载过程中包括孔隙、横向裂纹和纵向裂纹在内的缺陷演变。提取了孔隙、横向裂纹和纵向裂纹的数量和体积。发现大多数孔隙和横向裂纹趋于压实。然而，高压缩载荷会导致上表面附近的纵向裂纹扩展，从而导致试样失效。将具有形态和位置信息的实际缺陷引入有限元模型。讨论了不同类型缺陷对力学行为的影响。发现压缩时纵向裂纹对力学行为的影响比横向裂纹更大。横向裂纹的存在有助于纵向裂纹的演变。本研究可能有助于增材制造陶瓷材料的工艺优化和性能提升。
