SMA碟簧群的循环受压性能及简化模型

CYCLIC COMPRESSIVE BEHAVIOR AND SIMPLIFIED MODEL OF SMA DISC SPRING SERIES

该研究提出将多个形状记忆合金(SMA)碟簧片并联排列形成碟簧组,然后在碟簧组间加入垫片分隔、串联排列形成碟簧群,以提供更高的承载力及变形能力。采用有限元软件ABAQUS建立了一系列SMA碟簧群的三维精细化有限元模型,并进行非线性循环受压分析。结果表明:与钢碟簧的“三角形”荷载-位移曲线相比,SMA碟簧群的荷载-位移曲线呈现鲜明的“旗帜形”特性,具有明显的正向及反向转变平台。随着碟簧片数的增加,碟簧组的总可恢复变形量基本不变,极限承载力及割线刚度近似成比例增加,而随着碟簧组数的增加,碟簧群的总可恢复变形量增加,极限承载力不变,割线刚度近似成比例降低。因此,可根据碟簧群总极限承载力及变形能力的需要,灵活调整碟簧片及碟簧组的数量及布置方式。碟簧组的各层碟簧片由于边界条件不同,应力分布存在明显差异,而变形量亦呈现两端大中间小的哑铃形分布模式,其中加载端碟簧片变形量最大,若超过极限变形量可能发生翻转失效,值得注意。提出了SMA碟簧群的简化模型,通过简化及精细模型的非线性循环受压分析,发现该简化模型的循环受压荷载-位移曲线与精细模型吻合良好,而计算效率提高约38倍。将SMA碟簧群应用于自复位NZ梁柱节点中,并对自复位钢框架进行了验证性的滞回分析。结果表明:采用SMA碟簧群的自复位钢框架最大侧移为4%时可完全复位,且二次刚度相比采用预应力钢绞线的传统自复位钢框架提高近100%,极限承载力提高70%。

In this study,several layers of SMA disc springs were arranged in parallel to form a disc spring group,and then gaskets were added between the spring groups,which were then arranged in series to form a disc spring series in order to provide higher bearing capacity and deformation capacity.The finite element software ABAQUS was used to establish a series of 3D refined finite element models of SMA disc spring series,and nonlinear cyclic compression analyses were carried out.The results show that compared with the triangular load-displacement curve of steel disc springs,the load-displacement curve of SMA disc spring series presents a distinct flag shape with obvious forward and reverse transition platform.With the increase of the number of spring groups,the total recoverable deformation of the disc spring series increases,and the ultimate bearing capacity remains unchanged.The secant stiffness decreases with the increase of the number of disc springs,and the total recoverable deformation remains unchanged.Therefore,the number and arrangement of disc springs and disc spring groups can be flexibly adjusted according to the required total ultimate bearing capacity and deformation capacity of disc spring series.Due to the difference in boundary conditions,the stress distribution in different layers of disc springs in a groups is obviously different,and the deformation also presents a dumbbell distribution pattern with higher deformation at the ends and smaller deformation in the middle.The loading end of the disc spring series has the largest deformation,and an overturn failure may occur if it exceeds the deformation limit of the disc spring,which is worth noting.Secondly,a simplified model was proposed for SMA disc spring series.Through nonlinear cyclic compression analyses,it is found that the load-displacement curve of the simplified model is in good agreement with the refined model,while the computational efficiency is improved by about 38 times.A self-centering steel beam-column connection was proposed adopting the SMA disc spring series,and verifying cyclic analysis was conducted on the self-centering steel frame.The results show that the self-centering steel frame with SMA disc spring series can completely return to the original position under a maximum lateral drift of 4%,and the secondary stiffness and ultimate bearing capacity of the self-centering steel frame with SMA disc spring series are nearly 100%and 70%higher than the traditional self-centering steel frame with steel strand.