Termini Dolores, Federici John, Gatley Ian, Rizzo Louis
Department of Physics, New Jersey Institute of Technology, 323 Dr. M.L.King. Jr. Blvd., Newark, NJ 07102, USA.
U.S. Army DEVCOM Armaments Center, Picatinny Arsenal, Wharton, NJ 07885, USA.
Polymers (Basel). 2024 Nov 26;16(23):3296. doi: 10.3390/polym16233296.
3D printing has become essential to many fields for its low-cost production and rapid prototyping abilities. As 3D printing becomes an alternative manufacturing tool, developing methods to non-destructively evaluate defects for quality control is essential. This study integrates the non-destructive terahertz (THz) analysis methods of terahertz time-domain spectroscopy (THz-TDS) and terahertz computed tomography (THz CT) to image and assess 3D printed resin structures for defects. The terahertz images were reconstructed using MATLAB, and the rotational symmetry of various structures before and after the introduction of defects was evaluated by calculating the mean squared deviation (MSD), which served as a symmetry parameter to indicate the presence of defects. Structures A and B had MSD values that were at least three standard deviations larger after introducing defects to their structures, showing a significant change in symmetry and indicating the existence of defects. Similarly, in structure C, blockages in parts made with different post-cures were identified based on the increase in MSD values for those slices. For structure D, the presence of a defect increased the MSD value by 14%. The results of this study verify that the MSD calculated for the rotational symmetry of the structures was greater when defects were present, accurately reflecting the anticipated breaks in symmetry. This paper demonstrates that terahertz imaging, combined with MSD analysis, is a viable procedure to identify and quantify defects in rotationally symmetric 3D printed structures.
3D打印因其低成本生产和快速成型能力，已成为许多领域的关键技术。随着3D打印成为一种替代制造工具，开发无损评估缺陷以进行质量控制的方法至关重要。本研究整合了太赫兹时域光谱（THz-TDS）和太赫兹计算机断层扫描（THz CT）的无损太赫兹（THz）分析方法，对3D打印树脂结构进行成像和缺陷评估。太赫兹图像通过MATLAB重建，通过计算均方差（MSD）评估引入缺陷前后各种结构的旋转对称性，该均方差用作表示缺陷存在的对称参数。结构A和B在引入缺陷后，其MSD值至少比标准差大三倍，显示出对称性的显著变化并表明存在缺陷。同样，在结构C中，根据不同后固化制成部分的切片MSD值增加，识别出堵塞情况。对于结构D，缺陷的存在使MSD值增加了14%。本研究结果证实，存在缺陷时，为结构旋转对称性计算的MSD更大，准确反映了预期的对称性破坏。本文表明，太赫兹成像与MSD分析相结合，是识别和量化旋转对称3D打印结构中缺陷的可行方法。
