基于抗振动疲劳的薄板加筋设计分析

Analysis on stiffen design of a skin plate by anti-vibration fatigue

振动是航空薄板常见的载荷形式,通常采用加强筋来减小振动幅度,从而提高薄板寿命.研究薄板的抗振动疲劳加筋方法,探讨加强筋与板的连接方式以及加强筋的布置方向对薄板振动与疲劳的影响机制.首先,基于振动理论和板筋变形协调条件,建立加筋薄板的运动方程.然后,建立铆接、点焊和滚焊连接形式的加筋薄板有限元模型,探讨连接单元的动力学建模方法;在此基础上,研究连接形式和加筋安装方向对薄板结构动力学特性的影响;最后,结合动力响应分析探讨板筋连接方式和加筋安装方向对疲劳寿命的影响.研究结果表明,双向加筋薄板在低频振动时刚度高于单向加筋薄板,双向加筋有利于提高结构抗疲劳强度,铆接单向加筋薄板的振动疲劳寿命最短.

Vibration is one of the common loading types to aircraft plate. It is frequent to use thestiffen method to reduce the vibration amplitude so as to improve the vibration fatigue life of thinplate. In order to study the anti-vibration fatigue method by stiffen, it is aimed to reveal the impactsof connecting method and connecting direction of stiffen on the vibration fatigue life of athin plate. Firstly, the kinetic equation of a stiffen plate was set up by combining the vibrationtheory of thin plate and the deformation compatibility condition of plate and stiffen. Then the typicalstiffen plate was employed to study the modeling method of the link element between theplate and the stiffen beam via building up the finite element dynamics model of stiffened platestructure with rivet, spot-weld and rolling-weld. Therefore, the dynamics properties of single-directionand double-direction stiffened plate were studied and the impacts of stiffen on the vibrationproperties were discovered. Finally, the fatigue life of the structure was estimated based onthe analysis of the dynamic response. Meanwhile, the influence of the connection mode and the directionof the connection on the fatigue life was studied. Results indicate that the stiffness of thesingle-direction stiffened plate is higher than that of the double-direction stiffened plate. Doubledirectionstiffened plate is benefit to the strength of vibration fatigue for the thin plate and the fatiguelife of the rivet stiffened plate is the minimum.