Eschen Kevin, Granberry Rachael, Holschuh Bradley, Abel Julianna
Department of Mechanical Engineering, University of Minnesota, Minneapolis, Minnesota 55455, United States.
College of Design, University of Minnesota, St. Paul, Minnesota 55108, United States.
ACS Appl Mater Interfaces. 2020 Dec 2;12(48):54155-54167. doi: 10.1021/acsami.0c14206. Epub 2020 Nov 17.
This work reexamines traditional shape memory alloy (SMA) loading paths commonly used in SMA-based actuator applications and presents a novel, superimposed condition in which SMA generates substantial forces upon heating and cooling. This atypical effect, which is investigated with a textile-based actuator, was found to be prominent at the completion of material phase transformation, at which point thermal expansion/contraction became the dominant force-generating mechanism. We demonstrate that amplification of generated forces can be accomplished by varying the applied thermal load, applied structural strain, as well as actuator architecture. Specifically, we present SMA knitted actuators as an actuator architecture that increases the effect by aggregating SMA wires within a complex strain profile-effectively providing a larger operational window for the effect to propagate. The amplification of blocking forces through this novel operational procedure suggests reconsidering traditional blocking force design paradigms and opens untapped actuator application spaces, such as the highlighted medical and aerospace wearable technologies.
这项工作重新审视了形状记忆合金（SMA）基致动器应用中常用的传统加载路径，并提出了一种新颖的叠加条件，即SMA在加热和冷却时会产生巨大的力。用基于纺织品的致动器研究了这种非典型效应，发现该效应在材料相变完成时最为显著，此时热膨胀/收缩成为主要的力产生机制。我们证明，通过改变施加的热负荷、施加的结构应变以及致动器结构，可以实现产生力的放大。具体而言，我们提出了SMA针织致动器作为一种致动器结构，通过在复杂应变分布内聚集SMA丝来增强这种效应，有效地为该效应的传播提供了更大的操作窗口。通过这种新颖的操作程序实现的锁止力放大表明需要重新考虑传统的锁止力设计范式，并开辟了未开发的致动器应用空间，如突出的医疗和航空航天可穿戴技术。
