针对强风作用下的大跨度桥梁或高速飞行中的机翼可能出现大振幅颤振响应,而现有时域自激力模型又无法模拟大振幅下的非线性气动力问题.提出一种新的非定常大振幅自激气动力模型及其参数拟合方法,新模型通过附加非线性微分方程组及附加气动力自由度来模拟气动力记忆效应及振幅非线性特性.对于同一主梁断面,使用一组模型参数即可模拟不同折算风速和不同振幅下的自激力,模型参数可通过风洞试验或CFD数值模拟结果拟合获得.结果表明,新模型能再现自激力阻尼特性随折算风速和振幅的变化,通过单频振动拟合得到的新模型能再现多频振动下的非线性自激力时程.%In simulation of long-span bridge and airfoil flutter, a large-amplitude motion-induced force model is required. However, existing time-domain motion-induced force models cannot simulate memory effects and amplitude dependency simultaneously. This paper proposes a new time-domain non-linear motion-induced force model, which employs a set of nonlinear differential equations and augmented aerodynamic degrees of freedoms to simulate memory effects and amplitude dependency. Motion-induced forces under different deck motion amplitudes, different reduced wind velocities and non-sinusoidal motions can be simulated using a single set of model parameters. A fitting algorithm for the new model is also proposed and the model parameters of a bridge deck are fitted using results obtained by CFD simulations. Numerical example shows that the new model can reproduce variation of aerodynamic damping characteristics with reduced wind velocity and amplitude. A model fitted using single-frequency forced vibration tests can reproduce forces generated by multi-frequency vibrations.
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