薄壁结构干摩擦阻尼减振设计分析

Design Analysis for Dry Friction Damping Vibration Suppression of Thin-walled Structures

加装干摩擦阻尼结构是航空发动机薄壁结构有效的减振手段。为提供工程可用高效的减振设计工具,建立了一种薄壁结构干摩擦阻尼减振设计的分析方法及流程。给定薄壁结构的振动应力,针对不同的减振结构采用恰当的干摩擦接触模型,基于能量耗散,计算干摩擦减振结构接触面所能提供的等效阻尼比,获得在所关注模态下减振结构所能提供的等效阻尼比随主结构考核点振动应力变化的阻尼特性曲线。减振设计阶段目标为共振发生时,在结构许用振动应力下,减振结构能提供最优的阻尼比。对4种常用的干摩擦阻尼结构进行了减振设计分析,结果表明:平板式缘板阻尼器优化质量为1.2 g、涡轮叶片锯齿冠优化预扭角为0.5°(取许用振动应力50 MPa)时可得最佳阻尼效果;矩形截面阻尼环径向厚度和裂式阻尼套筒轴向长度在设计范围内取值越大,阻尼效果越好。

Adding dry friction damping structure is an effective vibration reduction method for aeroengine thin-walled structures.In order to provide an efficient vibration reduction design tool for engineering,an analysis method and process of dry friction damping design for thin-walled structures were established.Given the vibration stress of thin-walled structures,appropriate dry friction contact models were adopted for different damping structures.Based on energy dissipation,the equivalent damping ratio provided by the contact surface of dry friction damping structures was calculated,and the damping characteristic curve of the equivalent damping ratio provided by the damping structures under the concerned mode varying with the vibration stress of the main structure assessment point was obtained.The objective of the damping design stage was to provide the optimal damping ratio under the allowable vibration stress of the structure when resonance occurs.The vibration reduction design and analysis of four commonly used dry friction damping structures were carried out.The re-sults show that the optimal damping effect can be obtained with the optimal mass 1.2 g of the under-platform damper and the optimal pre-twist angle 0.5°of the zig-zag shroud,and the larger the radial thickness of the ring damper and the axial length of the split sleeve,the better the damping effect for the labyrinth seal and vortex reducer duct,respectively.