Examining layer height effects on the flexural and fracture response of plain and fiber-reinforced 3D-printed beams
Examining layer height effects on the flexural and fracture response of plain and fiber-reinforced 3D-printed beams
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DOI：
10.1016/j.cemconcomp.2021.104254
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发表时间：
2021-11
影响因子：
10.5
通讯作者：
Sooraj A.O. Nair;Avinaya Tripathi;N. Neithalath
中科院分区：
文献类型：
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作者：
Sooraj A.O. Nair;Avinaya Tripathi;N. Neithalath
大量的工作集中在数字制造（3D打印）的混凝土混合物的开发及其流变和机械性能。然而，对于基于挤出的分层制造，选择适当的打印参数也很重要，这些参数可能会影响3D打印元件的性能。在众多参数中，本文重点介绍了层高，它直接影响到流变要求、印刷质量、总印刷时间和层间粘合。具体来说，本文研究了层高度（5，10和15 mm层高度对应于喷嘴直径的25，50和75%，即20 mm）对3D打印梁的抗弯强度和断裂性能的影响。弯曲和断裂性能表明，较小的层高对未增强和纤维增强的3D打印砂浆有利，即使这会导致更多的界面和更长的打印时间。少量的钢纤维增强被证明是有用的，在消除弱界面上测得的散装性能的负面影响，平均抗弯强度高30-40%，断裂韧性和裂纹尖端张开位移高近30%，相比平原混合物。应变能释放率，数字图像相关性和光学图像/显微照片用于解释无缺口四点和缺口三点弯曲下分层3D打印砂浆中的裂纹扩展。
A significant amount of work has focused on the development of concrete mixtures for digital manufacturing (3D printing), and their rheological and mechanical properties. However, for extrusion-based layered manufacturing, it is also important to select the appropriate printing parameters that have the potential to impact the performance of 3D printed elements. Among the many such parameters, this paper places emphasis on layer height, which has a direct bearing on rheology requirements, print quality, overall printing time, and interlayer bonding. Specifically, this paper examines the effects of layer height (5, 10, and 15 mm layer heights corresponding to 25, 50, and 75% of the nozzle diameter, which is 20 mm) on the flexural strength and fracture properties of 3D printed beams. Flexural and fracture properties indicate that smaller layer heights are beneficial for unreinforced and fiber-reinforced 3D printed mortars, even though this results in greater number of interfaces and longer printing times. A small amount of steel fiber reinforcement is shown to be useful in eliminating the negative effects of weak interfaces on the measured bulk properties, with average flexural strengths higher by 30–40% and fracture toughness and crack tip opening displacement higher by almost 30% as compared to plain mixtures. Strain energy release rates, digital image correlation, and optical images/micrographs are used to explain crack propagation in layered 3D printed mortars under unnotched four-point, and notched three-point bending.