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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) environments. 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 former 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 stitches 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]

The purpose of this research is to clarify the contractile force mechanism of a shape memory alloy (SMA) knitted fabric actuator. We knitted SMA yarn with plain stitches. We then determined the limit up to which SMA plain knitted fabric can be uniaxially elongated and thereafter the original dimensions can be recovered through its repeated heating. Moreover, the temperature dependence of SMA plain knitted fabric in the case of contractile force is quantitatively evaluated experimentally by heating it and then measuring its tension after it is extended to a certain length and fixed at both ends. The results show that, in its wale direction, the maximum tension by heating exceeds the tension corresponding to the extension. Furthermore, it is confirmed that theoretical calculations for the tensile properties of the knitted fabric of spun yam and filament yarn can be applied to plain knitted fabric of SMA yarn. Using this theoretical calculation, and the flexural rigidity measured by KES system, it is clarified the contractile force of the SMA knitted fabric actuator is affected not only by contraction of SMA yarn but also an increase in its flexural rigidity. [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]