Session: SYMP 3-5: Actuator Systems

Paper Number: 140501

140501 - Optimization of Niti Microfilament Yarns 

NiTi microfilament yarns are promising as an artificial muscle because of their high mechanical strength, actuation efficiency, and energy density. Additionally, NiTi microfilament yarns have low flexural rigidities, which enables them to be easily integrated into textiles. Textiles made from NiTi microfilament yarns have demonstrated large distributed contraction and generated forces necessary to realize active compression garments and tunable energy absorption for load-distributing applications such as prosthetic socket liners and pressure ulcer mitigation. While promising for diverse applications, little is understood about how to design and manufacture the NiTi microfilament yarns to meet the performance specifications for these applications. Previously, a model was derived to predict the mechanical performance of superelastic NiTi microfilament yarns with known yarn geometries and manufacturing parameters. The model accurately predicted the impact of yarn twist on mechanical performance for yarns made from a single filament diameter and a constant number of filaments. This research expands the previous model and optimizes material properties, yarn geometry, and manufacturing parameters to tailor the mechanical and functional performance of NiTi microfilament yarns. The previous model is expanded to include various NiTi microfilament yarn geometries. These modifications are verified by comparing the obtained transition regions and the yarn force response to the experimental results. The model provides further understanding and insight into the control of NiTi microfilament yarn for desired applications. We establish objective functions to optimize for actuation contraction, force generation, and efficiency of NiTi microfilament yarns that use the shape memory effect. For yarns that use the superelastic effect, the objective function optimizes energy absorption potential. The yarn parameters involved in this optimization process are the number of filaments, filament radius, yarn density, and yarn radius. The manufacturing parameters are the spindle speed and delivery speed. Precise control over the yarn's structure, and thus its thermal and mechanical behavior, can be achieved by selecting the yarn and manufacturing parameters. We dedicated various levels to each of these parameters and performed the design of experiments based on those levels to achieve the specific performance and improve efficiency. The optimization process significantly enables the inverse design of NiTi microfilament yarns. Through optimization, by setting desired levels for the design parameters, the yarn is thermally and mechanically ideal for use in desired applications. This comprehensive optimization study is pivotal for enhancing the performance of SMA microfilament yarns while aiming to improve their overall efficiency, reduce energy use, and minimize material use.

Presenting Author: Mohammad Reza Farahani University of Minnesota

Presenting Author Biography: As a PhD student in Mechanical Engineering, Mohammad Reza Farahani is currently dedicating his research efforts towards the innovative field of smart materials, under the guidance of Professor Julianna Abel at the Design of Active Materials and Structures Lab (DAMSL). His role as a research assistant allows him to deeply engage with the model-based design of smart materials and structures, specifically focusing on the exploration of geometric and textile-based architectures.

His research is fundamentally aimed at establishing comprehensive frameworks for the design and synthesis of advanced smart material technologies. The core of his work seeks to unlock new possibilities for medical devices, aerospace structures, and consumer products by leveraging the unique properties of smart materials.

Authors:

Mohammad Reza Farahani
Julianna Abel