Sequential Self-Folding of Shape Memory Polymer Sheets by Laser Rastering Toward Origami-Based Manufacturing
Sequential Self-Folding of Shape Memory Polymer Sheets by Laser Rastering Toward Origami-Based Manufacturing
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DOI：
10.1115/1.4050463
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发表时间：
2021-09-01
影响因子：
4
通讯作者：
Bedewy, Mostafa
中科院分区：
文献类型：
--
作者：
Abdulhafez, Moataz;Line, Joshua;Bedewy, Mostafa
基于折纸的制造策略为开发新的制造工艺打开了大门，新的制造工艺能够从二维(2D)板材生产复杂的三维(3D)几何图形。然而，为了将这些方法转化为可扩展的制造过程，需要创建受控折叠的快速技术。在这项工作中，我们提出了一种基于直接激光光栅化的形状记忆聚合物薄片可控自折叠的新方法。我们证明，快速移动二氧化碳激光在预应变聚苯乙烯薄片上会导致沿激光路径产生受控折叠。激光与聚合物的相互作用在玻璃化转变温度以上诱导局部加热，并在薄板厚度上产生温度梯度。由于聚合物的粘弹性松弛，这种温度梯度导致收缩梯度，有利于向较热的一侧(向激光光源)折叠。研究了激光功率、光栅化速度、光通量和扫描次数对折叠角的影响。此外，我们还研究了产生最高质量折叠的工艺参数，并将不需要的变形降至最低。我们的结果表明，我们可以创建高达甚至超过90度的干净折叠，这突出了我们的方法的潜力，即创建具有平滑表面光洁度的轻量级3D几何图形，而使用3D打印方法创建这些几何图形是具有挑战性的。因此，激光诱导聚合物的自折叠是一种本质上可大规模定制的制造方法，特别是当与切割相结合以整合折纸和Kirigami时。
Origami-based fabrication strategies open the door for developing new manufacturing processes capable of producing complex three-dimensional (3D) geometries from two-dimensional (2D) sheets. Nevertheless, for these methods to translate into scalable manufacturing processes, rapid techniques for creating controlled folds are needed. In this work, we propose a new approach for controlled self-folding of shape memory polymer sheets based on direct laser rastering. We demonstrate that rapidly moving a CO2 laser over pre-strained polystyrene sheets results in creating controlled folds along the laser path. Laser interaction with the polymer induces localized heating above the glass transition temperature with a temperature gradient across the thickness of the thin sheets. This gradient of temperature results in a gradient of shrinkage owing to the viscoelastic relaxation of the polymer, favoring folding toward the hotter side (toward the laser source). We study the influence of laser power, rastering speed, fluence, and the number of passes on the fold angle. Moreover, we investigate process parameters that produce the highest quality folds with minimal undesired deformations. Our results show that we can create clean folds up to and exceeding 90 deg, which highlights the potential of our approach for creating lightweight 3D geometries with smooth surface finishes that are challenging to create using 3D printing methods. Hence, laser-induced self-folding of polymers is an inherently mass-customizable approach to manufacturing, especially when combined with cutting for integration of origami and kirigami.