【摘 要】
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This study has developed a nonlinear mathematical model for unsteady self-excited forces(USEF)acting on a slender prism to address the shortcomings of the classical quasi-steady theory in predicting g
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This study has developed a nonlinear mathematical model for unsteady self-excited forces(USEF)acting on a slender prism to address the shortcomings of the classical quasi-steady theory in predicting galloping instabilities of prisms.The USEF and galloping response prism were obtained from a hybrid aeroelastic-pressure base(HAPB)wind tunnel test.It was found that the galloping response predicted by the USEF matches well with the experimental result whereas the quasi-steady theory cannot accurately predict the galloping instability.According to an energy method,the USEF was quantitatively decomposed into three components: an aerodynamic damping force component,an aerodynamic stiffness force component and a remain force component.Only the aerodynamic damping and aerodynamic stiffness components input energy to an oscillation system.Accordingly,a nonlinear mathematical model of the USEF that is a 5th-order polynomial function with respect to the aerodynamic damping and stiffness force components was established.The results indicated that the 5th-order model was accurate in predicting galloping instabilities of the prism.For the purpose of convenient use,a simplified 3rd-order nonlinear mathematical model was obtained as high-order terms in the 5th-order model have a slight effect on galloping response.The results showed that the 3rd-order model can precisely predict galloping instabilities of prisms with different mass-damping ratios.
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