ABSTRACT: The performance enhancement of aircraft coupled with the development of increasingly lightweight and flexible materials has led designers to use smaller structural safety factors along the time, which can make aerodynamic surfaces more susceptible to aeroelastic phenomena, including flutter. This kind of occurrence must be carefully investigated by ground and flight tests during aircraft development and certification, which requires suitable instrumentation in order to predict the occurrence of unwanted vibrations. The sensors in this kind of application must be less intrusive as possible, in order to not modify the dynamic or aerodynamic behavior of the system. This work proposes the use of infrared imaging as a tool for flutter detection, analyzing the suitability of the technique for this application. For this purpose, a literature review was performed by presenting infrared technology concepts; then, some preliminary tests were performed in a structure to predict flutter characteristics, and finally wind tunnel tests were executed in the same structure, validating this technique and highlighting its positive points and points that need improvement.

ABSTRACT: In recent years, advances in aeronautical engineering field include, among others, the development of increasingly lightweight and flexible materials, allowing better performance of systems in applications such as Unmanned Aerial Vehicles, photographic model airplanes, light weight aircraft etc. This progress, however, can cause difficulties in design and various types of tests, such as those performed in modal analysis, since the instrumentation weight and shape can influence the behavior of very light and aerodynamic structures. This paper proposes a new technique to perform modal analysis in simple structures, eliminating the use of accelerometers, which must be numerous in this type of analysis and have significant weight; the whole structure can be analyzed at the same time, and this is an advantage in comparison with other techniques as vibrometer laser, that analyses one point at a time. The technique in question makes use of infrared imaging, detecting, through the heat, the structure deformation, allowing the trace of its modal shape. For this, a theoretical analysis and a thermomechanical modeling of a known structure are performed, with subsequent test to be validated, and finally the conclusions and suggestions for future work are presented.

The purpose of this study is to apply inverse dynamics control for a six degree of freedom flight simulator motion system. Imperfect compensation of the inverse dynamic control is intentionally introduced in order to simplify the implementation of this approach. The control strategy is applied in the outer loop of the inverse dynamic control to counteract the effects of imperfect compensation. The control strategy is designed using H∞ theory. Forward and inverse kinematics and full dynamic model of a six degrees of freedom motion base driven by electromechanical actuators are briefly presented. Describing function, acceleration step response and some maneuvers computed from the washout filter were used to evaluate the performance of the controllers.

This article deals with a contour error controller (CEC) applied in a high speed biaxial table. It works simultaneously with the table axes controllers, helping them. In the early stages of the investigation, it was observed that its main problem is imprecision when tracking non-linear contours at high speeds. The objectives of this work are to show that this problem is caused by the lack of exactness of the contour error mathematical model and to propose modifications in it. An additional term is included, resulting in a more accurate value of the contour error, enabling the use of this type of motion controller at higher feedrate. The response results from simulated and experimental tests are compared with those of common PID and non-corrected CEC in order to analyse the effectiveness of this controller over the system. The main conclusions are that the proposed contour error mathematical model is simple, accurate, almost insensible to the feedrate and that a 20:1 reduction of the integral absolute contour error is possible.