Vlăsceanu Daniel, Popescu Diana, Baciu Florin, Stochioiu Constantin
Department of Strength of Materials, Faculty of Industrial Engineering and Robotics, National University of Science and Technology Politehnica Bucharest, 060042 Bucharest, Romania.
Department of Robotics and Production Systems, Faculty of Industrial Engineering and Robotics, National University of Science and Technology Politehnica Bucharest, 060042 Bucharest, Romania.
Polymers (Basel). 2024 Aug 20;16(16):2359. doi: 10.3390/polym16162359.
This paper examined the mechanical properties of wrist-hand orthoses made from polylactic acid (PLA) and polyethylene terephthalate glycol (PETG), produced through material extrusion with infill densities of 55% and 80%. These orthoses, commonly prescribed for wrist injuries, were 3D-printed flat and subsequently thermoformed to fit the user's hand. Experimental and numerical analyses assessed their mechanical resistance to flexion after typical wear conditions, including moisture and long-term aging, as well as their moldability. Digital Imaging Correlation investigations were performed on PLA and PETG specimens for determining the characteristics required for running numerical analysis of the mechanical behavior of the orthoses. The results indicated that even the orthoses with the lower infill density maintained suitable rigidity for wrist immobilization, despite a decrease in their mechanical properties after over one year of shelf life. PLA orthoses with 55% infill density failed at a mean load of 336 N (before aging) and 215 N (after aging), while PETG orthoses did not break during tests. Interestingly, PLA and PETG orthoses with 55% infill density were less influenced by aging compared to their 80% density counterparts. Additionally, moisture and aging affected the PLA orthoses more, with thermoforming, ongoing curing, and stress relaxation as possible explanations related to PETG behavior. Both materials proved viable for daily use, with PETG offering better flexural resistance but posing greater thermoforming challenges.
本文研究了由聚乳酸（PLA）和聚对苯二甲酸乙二醇酯（PETG）制成的手腕矫形器的力学性能，这些矫形器通过材料挤出工艺生产，填充密度分别为55%和80%。这些常用于手腕损伤的矫形器先通过3D打印成平面，随后进行热成型以贴合使用者的手部。实验和数值分析评估了它们在典型使用条件（包括受潮和长期老化）下对弯曲的力学抗性以及可成型性。对PLA和PETG样本进行了数字图像相关研究，以确定对手腕矫形器力学行为进行数值分析所需的特性。结果表明，即使是填充密度较低的矫形器，在保质期超过一年后力学性能有所下降，但仍保持了适合手腕固定的刚性。填充密度为55%的PLA矫形器在平均载荷336 N（老化前）和215 N（老化后）时失效，而PETG矫形器在测试过程中未断裂。有趣 的是，填充密度为55%的PLA和PETG矫形器相比填充密度为80%的同类产品，受老化的影响较小。此外，受潮和老化对PLA矫形器的影响更大，热成型、持续固化和应力松弛可能是与PETG行为相关的解释。两种材料都证明可用于日常使用，PETG具有更好的抗弯曲性能，但热成型挑战更大。
