摘要
采用弹簧悬挂节段模型测振的方法,研究了双边肋桥梁断面的软颤振响应。试验中观察到明显的软颤振现象,软颤振发生在扭转模态内,以单自由度的扭转振动为主,弯扭耦合效应比较微弱。将颤振导数拓展为瞬时扭转振幅的函数,以计入自激力的非线性效应。参数识别结果表明,自激力的非线性主要体现为气动阻尼的非线性效应,气动刚度的非线性较弱。通过对比软颤振响应的计算值和试验值,初步验证了该自激力模型和参数识别结果的可靠性。根据气动阻尼和结构阻尼随瞬时振幅的变化关系,对软颤振的机理进行了探讨。
To investigate the soft flutter phenomenon,i.e.,nonlinear post critical limit cycle oscil1 ation （LCO）of a twin-side-girder section,a series of spring-suspended sectional model tests were conducted.Experimental results showed that the sectional model exhibits violent soft flutter phenomena in post flutter range;the observed soft flutter is a quasiharmonic nonlinear torsional vibration with a slight bending-torsion coupling effect;the classical linear self-excited force model by Scanlan is not applicable to soft flutter.To model the aerodynamic nonlinearity during large-amplitude oscillation of soft flutter,a nonlinear self-excited force model was proposed by expressing flutter derivatives of the classical Scanlan＇s linear model as functions of transient torsional vibration amplitude.The identified results of the amplitude-dependant flutter derivatives showed that the nonlinearity is strong for the aerodynamic damping and very weak for the aerodynamic stiffness.The feasibility of the proposed model and the reliability of the identified aerodynamic parameters were verified by comparing the computed vibration responses of soft flutter with the corresponding experimental data.The mechanism of soft flutter was then explored with the identified nonlinear relationships of aerodynamic damping and structural damping with respect to the transient torsional vibration amplitude.
出处
《振动与冲击》
EI
CSCD
北大核心
2016年第21期29-35,共7页
Journal of Vibration and Shock
基金
国家自然科学基金面上项目(51478360)
国家自然科学基金重大研究计划集成项目(91215302)
关键词
双边肋断面
软颤振
非线性自激力模型
非线性气动阻尼
软颤振机理
twin-side-girder section
soft flutter
post-critical LCO
nonlinear self-excited force model
nonlinear aerodynamic damping
soft flutter mechanism
