Development of ground vibration test based flutter emulation technique

Abstract

In demand of simpler and alternative ground flutter test, a new technique that emulates flutter on the ground has recently emerged. In this paper, an improvement of the test technique is made and verified through the experimental work. The technique utilizes general ground vibration test (GVT) devices. The key idea is to emulate the distributed unsteady aerodynamic force by using a few concentrated actuator forces; referred to as emulated flutter test (EFT) technique. The EFT module contains two main logics; namely, real-time aerodynamic equivalent force calculator and multi-input-multi-output (MIMO) force controller. The module is developed to emulate the subsonic, linear flutter on a specified target structure, which is a thin aluminum clamped-plate with aspect ratio (AR) of 2.25. In this study, doublet hybrid method (DHM) was applied to model the subsonic aerodynamic force, which restricts the application to a 2-dimensional structure. Given that, correlation of several experimental works, such as wind-tunnel flutter test, EFT using laser displacement sensor (LDS), and EFT using accelerometer, on the target structure are investigated to verify the technique. In addition to the flutter boundary, flutter mode shape and trend of aerodynamic damping effect are also presented in this work. Together with these various kinds of test results, application of more compact actuator and an accelerometer as a sensor, makes the current technique the most advanced ground flutter emulation test method.