Two-spring model for active compression textiles with integrated NiTi coil actuators
Two-spring model for active compression textiles with integrated NiTi coil actuators
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DOI：
10.1088/0964-1726/24/3/035011
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发表时间：
2015-03-01
影响因子：
4.1
通讯作者：
Newman, D.
中科院分区：
文献类型：
--
作者：
Holschuh, B.;Newman, D.
本文介绍了一个双弹簧模型的开发和实施，以预测混合压缩纺织品的性能相结合的被动弹性织物和集成NiTi形状记忆合金（SMA）线圈致动器。一个分析模型，将被动织物SMA线圈系统作为连体线性弹簧，预测服装被动和主动反压力作为11个设计变量的函数。对于固定SMA线圈设计（包含五个设计变量），该模型预测被动织物材料模量、初始长度、宽度和厚度决定被动反压幅度和激活冲程长度，并且被动和主动压力高度依赖于与肢体总周长相比的联合SMA织物系统的相对未拉伸长度。几个被动织物进行了测试，以确定其模量和一般评估织物线性模型的假设：两种织物（棉和氯丁橡胶）被发现表现线性高达200%的应变，而其他两种织物（平聚酯弹性和三层莱卡）被发现是非线性的，在相同的应变信封。五个假设的压缩止血带设计，采用实验确定的织物特性和先前研究的SMA致动器在麻省理工学院开发。讨论了每种止血带设计的性能，特别关注机械反压（MCP）航天服的设计要求，提出了实现完整MCP设计规范（> 29.6 kPa）同时最小化（< 5 mm）服装厚度的设计。在这项工作中开发的建模框架使压缩服装设计者能够基于各种设计参数来定制主动压缩服装的反压和激活冲程特性，以满足广泛的性能规格。
This paper describes the development and implementation of a two-spring model to predict the performance of hybrid compression textiles combining passive elastic fabrics and integrated NiTi shape memory alloy (SMA) coil actuators. An analytic model that treats passive fabricSMA coil systems as conjoined linear springs is presented to predict garment passive and active counter-pressure as a function of 11 design variables. For a fixed SMA coil design (encompassing five design variables), the model predicts that passive fabric material modulus, initial length, width and thickness determine both passive counter-pressure magnitude and activation stroke length, and that passive and active pressures are highly dependent on the relative unstretched lengths of the conjoined SMA-fabric system compared to the total limb circumference. Several passive fabrics were tested to determine their moduli and to generally assess the fabric linearity model assumption: two fabrics (spandex and neoprene) were found to behave linearly up to 200% strain, while two other fabrics (flat polyester elastic and a trilaminate Lycra) were found to be nonlinear in the same strain envelope. Five hypothetical compression tourniquet designs are presented using experimentally determined fabric characteristics and previously studied SMA actuators developed at MIT. The performance of each tourniquet design is discussed with a specific focus on mechanical counter-pressure (MCP) space suit design requirements, with designs presented that achieve the full MCP design specification (> 29.6 kPa) while minimizing (< 5 mm) garment thickness. The modeling framework developed in this effort enables compression garment designers to tailor counterpressure and activation stroke properties of active compression garments based on a variety of design parameters to meet a wide range of performance specifications.