Quasi-static cyclic behavior of wire rope isolators: comprehensive experimental study and improved mathematical modeling

Wire rope isolators (WRI) effectively isolate shocks and vibrations, making them an ideal choice for many industries, including military and aerospace. A sizeable experimental program was conducted to investigate the cyclic hysteretic behavior of WRIs in all possible loading directions. The test matrix included several isolators subjected to different load-displacement amplitudes at varying rates and other geometries and sizes of the WRIs themselves. This study evaluates the effective stiffness and damping characteristics of WRIs in both the tension/compression (or vertical) and shear/roll (or lateral) directions through laboratory tests and mathematical modeling. It was found that the wire rope diameter significantly influences the stiffness of the WRI more than the other geometric characteristics. Additionally, the damping characteristics of the WRI were found to be correlated to the height-to-width ratio for a given wire rope diameter. The cyclic loading tests showed that, unlike in the lateral directions, in the vertical direction, the load-displacement hysteresis loops are asymmetric. Therefore, the original Bouc-Wen model of hysteresis was used for the lateral direction. A modified version of the same model was developed to simulate the observed asymmetric hysteretic behavior in the vertical direction.