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图1  不同噪声到达率λ下系统随机稳定性参数空间(τ, α)

变化

图2  时滞对系统随机分岔的影响，当时滞参数在黄色区域选取时系统响应密度函数为火山口，即出现随机分岔，当参数在红色区域选取时系统响应密度函数为单峰，无随机分岔

图3  不同时滞参数τ2下系统随机稳定性参数空间(τ1, α)

Stochastic dynamics of a single degree-of-freedom quasi-linear system with multitime delays and Poisson white noises are investigated using an approximate procedure based on the stochastic averaging method. The simplified equations, including the averaged stochastic differential equation and the averaged generalized Fokker–Planck–Kolmogorov equation, are obtained to calculate the probability density functions (PDFs) to explore stationary responses. The expression of the Lyapunov exponent is presented to examine the asymptotic stochastic Lyapunov stability. An illustrative example of a quasi-linear oscillator with two Poisson white noises controlled by two time-delayed feedback forces is worked out to demonstrate the validity of the proposed method. The approximate stationary PDFs of stochastic responses and asymptotic stochastic stability are demonstrated numerically and theoretically. The results show that the Gaussian white noise has a stronger influence on the dynamics than the Poisson white noise with a small mean arrival rate. Moreover, the influence of the time delay and noise parameters on stochastic dynamics is investigated. It is found that the PDFs under the Poisson white noise approach those under Gaussian white noise as the mean arrival rate increases. The time delay can induce stochastic P-bifurcation of the system. It is also found that the increase of time delay and the mean arrival rates of the Poisson white noises will broaden the unstable parameter region. The comparison between numerical and theoretical results shows the effectiveness of the proposed method.

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