Influence analysis of joints on nonlinear dynamic characteristics of articulated structures

A dynamic model of articulated structures is proposed in view of the nonlinear dynamic characteristics of deployable structures caused by joints. Based on the lateral and radial geometric constraints of joints, the nonlinear characteristics of different size joints can be analyzed. The harmonic expressions of articulated structure parameters with nonlinear characteristics are obtained by using harmonic balance method (HBM). The expression can be introduced into the dynamic analysis of deployable structures for the purpose of converting the nonlinear dynamic equation of deployable structure into nonlinear algebraic equation. The effects of joints parameters on the dynamics of deployable structures are analyzed when the joints characteristics are changed. The natural frequency variation of structure with joints clearance, joints stiffness and excitation force is got. Considering the nonlinear characteristics of joints, the change law of natural frequency of structures with joints location and number is analyzed by solving the natural frequency ridge of structures. The influence function of the joints location and number upon the natural frequency of articulated structures is built, which can be extended to multi-dimensional and complex structures and can provide a method for the design and research of deployable structure. Runge-Kutta method is adopted to analyze the nonlinear structure to get the amplitude-frequency curve. The numerical results can validate the HBM for dynamic simulation of articulated structures.