Abstract: The disturbance generated by engine operation is a primary source of random vibration in the carrier aircraft. To investigate the impact of carrier aircraft random vibration on the launch process, a displacement excitation model for this vibration is constructed based on the stochastic harmonic function method. Integrating multibody dynamics theory and the fixed-interface component mode synthesis method, a rigid-flexible coupled dynamic model of a rearward ejection device is established. A simplified approach, which treats distributed nodal forces as equivalent concentrated forces, is employed to handle key contact forces. The GF-d point selection method combined with the Direct Probability Integral Method (DPIM) is utilized to solve the probability density functions of the response and the statistical characteristics of stress for critical components. ?Comparisons of the simulated statistical characteristics with different sample sizes show an error of less than 1.25%, thereby verifying the convergence of the results. Furthermore, simulations under multiple working conditions, analyzing the stress statistics and reliability assessment of these critical components, demonstrate ultra-high reliability, with failure probabilities below 10 ppb of the ejection device. It provides a credible and efficient approach for the modeling, statistical analysis of responses, and system reliability assessment of airborne rocket rearward ejection systems subjected to stochastic excitations.

Key words: carrier aircraft vibration, stochastic harmonic function method, direct probability integral method, rigid-flexible coupled model, launch dynamics