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Fluttering Behavior of a Flexible Thin Sheet in High Speed Air Flow

高速气流中柔性薄片的颤振行为

基本信息

批准号：
08650225
负责人：
YAMAGUCHI Nobuyuki
金额：
$ 1.34万
依托单位：
Meisei University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1997
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08650225/
关键词：
Aeroelasticity Flutter Flexible Sheet Fluid-Induced Vibration Stiffness Mass Ratio Progressive Wave Wind Tunnel Test 空気力学弾性学空力弾性振動渦

项目摘要

Process of moving and/or handling in air at high speed a very thin and flexible sheet of such as paper, plastic film, cloth, thin metal plate, etc. are utilized in many fields of industry. Accelerating such processes tends to cause fluttering of the sheet, thus having adverse effects on the product quality and the production efficiency. The phenomena are considered to be of aeroelastic instability (flutter) induced by the interference of the sheet elastic behavior and the aerodynamic excitation. This investigation aimed to establish a method for prediction and elucidation of the phenomena on both theoretical and experimental bases.Tests were conducted on sheets of papers with the leading edge fixed and the trailing edge freely blown in a small wind tunnel ; experimental data on flutter speeds, frequencies, and modes, etc. were collected for a wide variety of the sheet conditions. The experimental flutter limits were found to form a clear boundary in terms of relative stiffness (stiffness/dynamic pressure) vs.mass ratio, and the vibrational characteristics were summarized in terms of reduced frequency vs.mass ratio..At the same time, a prediction method of the flutter condition was developed utilizing a distributed vortex method for the fluid dynamics and an elastic beam theory for the sheet dynamics on the assumption of small perturbation. Results predicted by the method gave good agreement with the above experimental data and explained well the characteristics of the phenomena observed.It is also necessary to know about the effects of external disturbances tending easily to affect very thin sheets. This investigation includes experimentally obtained informations on such concerns.Thus the investigation, both experimental and theoretical, succeeded in forming a basis and providing a useful means for evaluating and tackling the practical situations.

在空气中高速移动和/或处理非常薄且柔性的片材（例如纸、塑料薄膜、布、薄金属板等）的过程被用于许多工业领域。加速这样的过程往往会导致片材颤动，从而对产品质量和生产效率产生不利影响。这种现象被认为是由片材弹性行为和气动激励的干扰引起的气动弹性不稳定（颤振）。本研究旨在建立一种在理论和实验基础上预测和解释这一现象的方法。在小型风洞中对前缘固定、后缘自由吹动的纸张进行了测试；针对各种板材条件收集了有关颤振速度、频率和模式等的实验数据。实验发现颤振极限在相对刚度（刚度/动压）与质量比方面形成了清晰的边界，并以降频与质量比的形式总结了振动特性。同时，在小扰动假设下，利用流体动力学的分布式涡流方法和片材动力学的弹性梁理论，开发了颤振条件的预测方法。该方法预测的结果与上述实验数据吻合良好，很好地解释了观察到的现象的特征。还需要了解外部扰动容易影响非常薄的板材的影响。这项研究包括通过实验获得的有关此类问题的信息。因此，实验和理论研究成功地为评估和解决实际情况奠定了基础并提供了有用的手段。