Abstract This study presents an efficient approach to investigate the nonlinear frequency response characteristics of aerospace morphing mechanism with clearances under random vibration excitation. First, a novel penalty stiffness calculation method based on an equivalent dynamic continuous contact model is first proposed. Through theoretical derivation, a quantitative relationship between the physical contact model and numerical algorithm is established. Numerical examples demonstrate that the proposed method provides more reasonable penalty stiffness values compared to the conventional geometry-driven principle, singnificantly improving contact penetration accuracy and substantially reducing the convergence failure rate. And then, the short-time Fourier transform (STFT) is applied to perform a time-frequency analysis on the sine-sweep test results of the aerospace morphing mechanism in Typical State 1. A frequency band of 100–120 Hz, at which the mechanism exhibits significant nonlinear dynamic characteristics. The acceleration curve extracted by this frequency band, is taken as the input of the finite element model of the aerospace morphing mechanism in Typical State 1 for simulation analysis. The proposed penalty stiffness calculation method is employed to determine the initial contact parameters,and the normal contact force is computed using the augmented Lagrange method. The model is then updated by correlating simulation results with experimental sweep data. Based on the updated model of Typical State 1, finite element models for Typical States 2 and 3 are established. The accuracy of the established models is confirmed by comparing the simulated frequency-domain response curves with corresponding experimental data for each state. Finally, the effects of joint clearance and friction on the frequency-response characteristics of the aerospace morphing mechanism in Typical States under random vibration excitation are systematically investigated. Based on the analytical results, the frozen coefficient method is employed to qualitatively derive the relationship surfaces among the modal frequencies of the aerospace morphing mechanism, joint clearance, and morphing time under random vibration conditions.
Zhang et al. (Sun,) studied this question.