Multidisciplinary Laboratory of Active Materials and Structures (LaMMEA), Department of Mechanical Engineering, Federal University of Campina Grande, Campina Grande 58429-140, Brazil.
CONSTRUCT-LFC, Civil Engineering Department, Faculty of Engineering, University of Porto, 4200-465 Porto, Portugal.
Sensors (Basel). 2022 Oct 21;22(20):8045. doi: 10.3390/s22208045.
Shape memory alloy (SMA) micro cables have a wide potential for attenuation of vibrations and structural health monitoring due to energy dissipation. This work evaluates the effect of SMA thermomechanical coupling during dynamic cycling and the fatigue life of NiTi SMA micro cables submitted to tensile loadings at frequencies from 0.25 Hz to 10 Hz. The thermomechanical coupling was characterized using a previously developed methodology that identifies the self-heating frequency. When dynamically loaded above this frequency, the micro cable response is dominated by the self-heating, stiffening significantly during cycling. Once above the self-heating frequency, structural and functional fatigues of the micro cable were evaluated as a function of the loading frequency for the failure of each individual wire. All tests were performed on a single wire with equal cross-section area for comparison purposes. We observed that the micro cable's functional properties regarding energy dissipation capacity decreased throughout the cycles with increasing frequency. Due to the additional friction between the filaments of the micro cable, this dissipation capacity is superior to that of the single wire. Although its fatigue life is shorter, its delayed failure compared to a single wire makes it a more reliable sensor for structural health monitoring.
形状记忆合金（SMA）微缆由于能量耗散而在衰减振动和结构健康监测方面具有广泛的应用潜力。本工作评估了 SMA 热机械耦合在动态循环过程中的影响，以及 NiTi SMA 微缆在 0.25 Hz 至 10 Hz 频率下承受拉伸载荷时的疲劳寿命。通过先前开发的方法对热机械耦合进行了表征，该方法确定了自加热频率。当微缆在高于该频率的情况下进行动态加载时，微缆的响应主要由自加热主导，在循环过程中显著变硬。一旦超过自加热频率，就可以评估微缆的结构和功能疲劳作为每个单独电线失效的加载频率的函数。所有测试均在具有相同横截面积的单根电线上进行，以便进行比较。我们观察到，随着频率的增加，微缆的能量耗散能力的功能特性在整个循环过程中逐渐降低。由于微缆中细丝之间的额外摩擦，这种耗散能力优于单丝。尽管其疲劳寿命较短，但与单丝相比，其延迟失效使其成为结构健康监测更可靠的传感器。
