Reduce-order dynamic modeling of X-braced girder considering flexible joints for analytical vibration characteristic investigation

Abstract

The task of establishing reduce-order dynamic model of complicated truss structures is increasingly difficult especially for flexible-jointed truss. New dynamic modeling approaches to achieve structural reduce-order dynamic model is of great significance for analytical vibration characteristic investigation. To this end, a novel dynamic parameter inverse analysis procedure for X-braced girder with flexible joints is proposed based on the Broyden–Fletcher–Goldfarb–Shanno (BFGS) algorithm and response surface methodology (RSM) in this study. Unknown equivalent stiffnesses and masses of the flexible-jointed X-braced girder are determined to further build its reduce-order dynamic model. Firstly, the energy method is utilized to estimate the initial values of equivalent parameters, which are used for inversion procedure in an effective manner. Secondly, the elastic characteristic of flexible joints is described by six-degree-of-freedom spring. Then, using the BFGS algorithm and RSM, the reduce-order dynamic model is obtained based on the frequencies calculated from the full-scaled finite model of the X-braced girder with flexible joints. Further, numerical results of natural properties and dynamic responses are presented to show the reliability of the proposed modeling method by comparing results with finite-element model data. The influence of the joint mass on the accuracy of the reduce-order dynamic model is discussed. Notably, considering the increasing use of truss structures with flexible joints in space engineering field, the proposed dynamic modeling method may represent an accurate and appealing alternative approach for constructing reduce-order model, whereas characteristics and reduce-order model of flexible-jointed truss structure are still difficult to estimate and establish using the existed achievements.