• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.38 no.6
• /
• pp.547-556
• /
• 2010

For the safety of aircraft and accuracy of bombs, many companies have researched the new concept of adaptive kit to flying-bombs. For the long distance flying, it's normally used deployed high-aspect ratio wing because of limited volume. The probabilities of large elastic deformation and flutter are increased due to decreased stiffness of high-aspect ratio wing. In this paper, computational fluid dynamics and computational structure dynamics interaction methodology are applied for prediction of aerodynamic characteristics. FLUENT and ABAQUS are used to calculate fluid and structural dynamics. Code-bridge was made base on the compactly supported radial basis function to execute interpolation and mapping. There are some differences between rigid body and fluid-structure interaction analysis which are results of aerodynamics characteristics due to structural deformation. Small successive vibration was observed by interaction.

• Aerospace Engineering and Technology
• /
• v.7 no.2
• /
• pp.205-212
• /
• 2008

This paper describes the modeling data and final analysis results of rotor resonance, rotor aeroelastic stability and whirl flutter stability for Smart UAV (SUAV). The effects of wing beamwise, chordwise and torsional stiffness on the whirl flutter stability were investigated considering the possibility of design change of SUAV wing structure. The parametric study showed that wing torsional and beamwise stiffness changes have much stronger influence on the wing mode damping than chordwise stiffness. It was analytically demonstrated that the final designed rotor system is aeroelastically stable and free from resonance, and that rotor/pylon/wing system of SUAV TR-S4 has enough rotor stability and whirl flutter stability margin.

• Smart Structures and Systems
• /
• v.3 no.1
• /
• pp.89-114
• /
• 2007

Two aspects of the design of a small-scale smart wing are addressed in this work, related to the ability of the wing to modify its cross section assuming the shape of two different airfoils and to the possibility of deflecting the profiles near the trailing edge in order to obtain hingeless control surfaces. The actuation is provided by one-way shape memory alloy wires eventually coupled to springs, Shape Memory Alloys (SMAs) being among the most promising materials for this kind of applications. The points to be actuated along the profiles and the displacements to be imposed are selecetd so that they satisfactorily approximate the change from an airfoil to the other and to result in an adequate deflection of the control surface; the actuators and their performances are designed so that an adequate wing stiffness is guaranteed, in order to prevent excessive deformations and undesired airfoil shape variations due to aerodynamic loads. The effect of the pressure distributions, calculated by way of the XFOIL software, and of the actuators loads, is estimated by FE analyses of the loaded wing. Two prototypes are then realised incorporating the variable airfoil and the hingeless aileron features respectively, and the verification of their shapes in both the actuated and non-actuated states, supported by image analysis techniques, confirms that interesting results are achievable with the proposed lay out and design considerations.

• Composites Research
• /
• v.35 no.2
• /
• pp.106-114
• /
• 2022

Carbon fiber-reinforced plastic, well known high specific strength and high specific stiffness, have been widely used in the aircraft industry. Mostly the CFRP structure is fabricated by lamination of carbon fiber or carbon prepreg, which has major disadvantage called delamination. Delamination is usually produced due to absence of the through-thickness direction fiber. In this study, three-dimensional carbon preform woven in three directions is used for fabrication of aircraft wing unit structure, a part of repeated structure in aircraft wing. The unit structure include skin, stringer and rib were prepared by resin transfer molding method. After, the 3D structure was compared with laminate structure through compression test. The results show that 3D structure is not only effective to prevent delamination but improved the mechanical strength. Therefore, the 3d preform structure is expected to be used in various fields requiring delamination prevention, especially in the aircraft industry.

• Journal of the Korean Society for Aviation and Aeronautics
• /
• v.18 no.1
• /
• pp.27-32
• /
• 2010

In this study, transonic flutter response characteristics have been studied for the AGARD 445.6 wing considering various turbulent models and several angle of attacks. The developed fluid-structure coupled analysis system is applied for flutter computations combining computational structural dynamics(CSD), finite element method(FEM) and computational fluid dynamics(CFD) in the time domain. The flutter boundaries of AGARD 445.6 wing are verified using developed computational system. For the nonlinear unsteady aerodynamics in high transonic flow region, DES turbulent model using the structured grid system have been applied for the wing model. Characteristics of flutter responses have been investigated for various angle of attack conditions. Also, it is typically shown that the current computation approach can yield realistic and practical results for aircraft design and test engineers.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.17 no.11
• /
• pp.2704-2710
• /
• 1993

A simple and straightforward method is introduced for developing continuum beam-rod model of a box-beam typed aircraft wing with composite layered skin based on "energy equivalence." The equivalent continuum structral properties are obtained from the direct comparison of the reduced stiffness and mass matrices for box-beam typed wing with those for continuum beam-rod model. The stiffness and mass matrices are all represented in terms of the continuum degrees-of freedom defined in this paper. The finite-element method. The advantage of the present continuum method is to give every continuum structural properties including all possible coupling terms which represent the couplings between different deformations. To evaluate the continuum method developed in this paper, free vibration analyses for both continuum beam-rod and box-beam are conducted. Numerical tests show that the present continuum method gives very reliable structural and dynamic properties compared to the results by the conventional finite-element analysis. analysis.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2014.10a
• /
• pp.189-192
• /
• 2014

Recently, development of electric powered UAV for high altitude and long endurance mission has been conducted worldwide. Long endurance requirement necessitates high lift over drag (L/D) aerodynamic characteristics and lightweight structures, leading to highly flexible wings with high aspect ratio. These highly flexible wings increase the danger of catastrophic aircraft failure due to flutter, which is a dynamic aeroelastic instability occurring from the interaction of aerodynamic, inertial, and elastic forces acting on the aircraft flying through the air. In this paper, flexible wing for electric powered UAV whose skin is fabricated using mylar film for lightweight design is briefly explained. In addition, flutter analysis procedures and results for the flexible wing in order to substantiate the aeroelastic stability requirements are presented.

• Journal of Aerospace System Engineering
• /
• v.9 no.1
• /
• pp.28-34
• /
• 2015

Armed aircraft of a basic trainer class installs external stores under wing box by using pylon and performs an operation such as weapon delivery and jettison, and should be designed to withstand all kinds of loads applied to external stores. The static strength test of pylons and wing box was performed to assess the static strength of pylon and their support structures for substantiation. Based on the test, the structures were verified to fully satisfy a given design requirement. In this paper, methods of test load generation of wing box and pylon, evaluation of test result data and design result of test set-up were presented. Comparing the FEM analysis with the same test data can lead to good match and reasonable deviation between both. Finally, based on the test and the analysis, the static strength of test article was substantiated and the reliability and effectiveness of analysis math model were obtained.

• Advances in aircraft and spacecraft science
• /
• v.6 no.1
• /
• pp.69-86
• /
• 2019

This paper discusses the use of the Digital Image Correlation (DIC) technique for the displacement and strain measurements of a wet lay-up composite wing. As opposed to classical strain gages, DIC allows to conduct full field strain analysis of simple to complex structural parts. In this work, wing-up bending tests and measurements of the composite wing of the Dardo Aspect by CFM Air are carried out through an ad-hoc test rig and the Q-400 DIC system by Dantec Dynamics. Also, the results are used to validate a finite element model of the structure under investigation.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.17 no.4
• /
• pp.551-559
• /
• 2014

The influence of the battle damage hole on the velocity and vorticity flow field have been studied by using particle image velocimetry. Time averaged velocity and vorticity vector fields in the vicinity of jet are presented. The perforated damage hole on a wing created from a hit by anti-air artillery was modeled as a 10% chord size hole which positioned at quarter chord. At low angles of attack, the vorticity in the forward side of the jet is cancelled due to mixing with the wing surface boundary layer. Stretching of vorticity in the backside of the jet generates a semi-cylindrical vortical layer that enclosing a domain with slow moving reverse flow. Conversely, at higher the angles of attack, the jet vorticity advected away from the wing surface and remains mostly confined to the jet. The mean flow behind the jet has a wake-like structure.