<p>The electromagnetic sled test platform exhibits complex nonlinear vibration characteristics under the excitation of synergistic effects due to the influence of self-excited vibration and aerodynamic lift from the test model. Metal plate and rubber combined structure vibration isolator are anticipated to deliver superior vibration attenuation performance for sled. However, the complex constitutive relation of rubber is always challenging to the change of excitation source. In this study, the nonlinear dynamics of metal-rubber-vibration subsystem is studied, and the dynamic characteristics under the synergistic effect of aerodynamic lift and harmonic excitation are emphatically discussed. A nonlinear Nishimura model-based on fractional-order is developed to describe the constitutive relationship of metal-rubber. The fractional order is defined by Caputo, the periodic solution is obtained by harmonic balance method, and the aperiodic response is numerically simulated. The amplitude-frequency characteristics of the system are obtained, and the complex nonlinear dynamic behavior of the system is verified by Poincaré mapping, phase diagram and spectrum diagram. The stability of dynamic response is further revealed by Lyapunov exponent and attraction basin. The multiplicity of amplitude-frequency response and the mechanism of periodic motion and chaotic transition are analyzed. The results show that the amplitude-frequency curve of the system exhibits a complex dynamic phenomenon with 5 coexisting solutions under combined excitation, and there are multiple types of bifurcations in the periodic motion and chaotic transition processes. The transition dynamics between periodic motion and chaos under varying excitation exhibit significant differences, and this transition process is inherently irreversible. The research in this paper provides theoretical guidance for the parameter design of metal-rubber vibration isolation system and its application in electromagnetic sled.</p>