Evaluation of Sliding Amount at Backlash Joints during Nonlinear Vibration of Extensible Truss

Abstract

This study evaluates the sliding amount at backlash joints on extensible space truss structures and examines the effects on the nonlinear vibration response. Previous study cannot directly evaluate the sliding amount at backlash joints on extensible truss due to the lack of sensors. Therefore, the purpose of this study is to grasp quantitatively the sliding amount at backlash joints and identify its effects on the nonlinearity of the vibration based on the acceleration output at more number of points. Acceleration sensors were attached to suitable points of horizontal and vertical members of the truss, which might move independently due to the existence of the backlash. As a result, it was found that each member was moving independently especially when the amplitude of the vibration was greater. Thus, this method is likely to capture quantitatively the sliding amount at backlash joints. Moreover, a time-frequency analysis of the acceleration data was performed. To this end, the wavelets transform was applied to the acceleration data and the relative acceleration data between the vertical and horizontal members. As a result, it was shown that the amplitude of higher frequency band damped faster for the relative acceleration data than each acceleration data, which captured how long the sliding at backlash continued in pin axis direction during nonlinear free vibration.