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The objective of this study was to improve the utility of a shape-memory-alloy (SMA) knitted fabric actuator. To that end, we employed a double-sided knitting structure with excellent structural stability and high yarn density and fabricated samples with different total number of courses, wales, and diameters of SMA fibers. These samples were subjected to repeated heating tests during uniaxial elongation along the direction of the wale, and the generated contraction force was measured. Furthermore, by comparing the results of the measurements, the influence of each parameter on the contraction force was evaluated. By including the amount of deformation in the direction of the knitting fabric width and the bending rigidity of the yarn in our analysis, we were able to determine the trend followed by the contraction force generated by SMA double-sided knitted fabrics. The results of this study are expected to be applicable to the development of smart textile products. [ABSTRACT FROM AUTHOR]

To improve the calculation accuracy of the contractile force in a shape memory alloy (SMA) knitted fabric actuator, which was developed in a previous study. we measured the Young's modulus, E, and wire diameter, d, of a SMA yarn in unheated (20 °C) and heated (100 °C) emironments. Subsequently, the contractile force in the heated environment was calculated in terms of bending rigidity (EI) using the measured values of E and d. The accuracy of the theoretical contractile force, considering contraction and increment in EI, was improved when compared with that in the fortner one. which only considered contraction of the SMA yarn. Furthermore, to enhance calculation accuracy, we proposed a 2 dimensional stitch model for SMA plain knitted fabric. This model consisted of clothoid curves through four contact points, where each yarn crosses the other slitelies and act forces. Further, this model could show the change in the curvature via the contraction of the yarn as well as the increase in its potential energy. Therefore, it was confirmed that this model is useful for calculating the contractile force of the SMA knitted fabric. [ABSTRACT FROM AUTHOR]