• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.04a
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• pp.217-221
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• 2007

In this study, forced vibrations analysis was performed for main wing of small scale WIG vehicle which is equipped two-stroke pusher type propeller engine, in terms of structural. for the frequency response analysis, excitations were assumed by H-mode(Horizontal mode), X-mode(Twisted mode) which is main vibration mode of engine, and for the transient response analysis, excitations were assumed by L-mode(Longitudinal mode) with propeller thrust which is occurred when it revolution.

• Journal of the Korea Institute of Military Science and Technology
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• v.16 no.4
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• pp.486-492
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• 2013

The pivoting composite wing is developed for the kit to be mounted on the external stores. The wing has a pivoting structure for the installation to an aircraft and high aspect ratio to increase lift drag ratio. The wing needs to be light and have sufficient strength and stiffness to satisfy structural design requirements. The wing is designed with carbon fiber composite and the structural parts are integrated to reduce cost to manufacture. In order to verify the structural performances, the design load analysis and flight load survey, the static analysis and test, the ground vibration test and flutter analysis are performed. It is shown that the wing has sufficient structural strength and stiffness to satisfy the structural design requirements.

• Journal of the Korean Society of Propulsion Engineers
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• v.4 no.3
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• pp.29-37
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• 2000

Because the previous design procedure for the composite wind turbine blade structure using trial and error method takes long time, a improved design procedure by using the program based on classical laminate theory was proposed to reduce the inefficient element. According to the improved design procedure, limitation of strains, stresses and displacements specified by international standard specification IEC1400-1 for the composite wind turbine blade were applied to sizing the structural configuration by using the rule of mixture and the principal stress design technique with a simplified turbine blade. Structural safety for strength and buckling stability was confirmed by the developed analysis program based on the laminate theory to minimize the design procedure. After modifying the preliminary design result with additional structural components such as skin, foam sandwich and mounting joints, stresses, strains, displacements, natural frequency, buckling load and fatigue life were analyzed by the finite element method. Finally these results were confirmed by comparing with IEC1400-1 specification.

• Journal of Aerospace System Engineering
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• v.17 no.6
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• pp.82-93
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• 2023

In this paper, nonlinear transonic flutter analyses of a composite missile fin considering the effect of delamination are conducted. An effective modal analysis methodology is adopted and verified with the experimental modal test data for laminated composite plates with delamination. Extended version of the in-house computational aeroelastic analysis program with the transonic small-disturbance (TSD) code is used in order to predict the flutter dynamic pressure of the delaminated composite fin models. In the subsonic, transonic, and supersonic flow regions, nonlinear time-domain flutter analyses are performed for various delamination conditions, and aeroelastic characteristics due to the delamination phenomena are examined in detail.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.11
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• pp.1028-1035
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• 2007

this study, forced vibration analysis was performed on the composite main wing structure of a small scale WIG craft which is equipped two-stroke pusher type reciprocating engine. The structural vibration analysis based on the finite element method was performed using a commercial FEM code, MSC/NASTRAN. Excitations for the frequency response analysis were assumed as the H-mode(horizontal mode), the V-mode(vertical mode) and the X-mode(twisted mode) which are typical main vibration modes of engine. And excitations for the transient response analysis were assumed as the L-mode(longitudinal mode) with the oscillating propeller thrust which occurs.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.8
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• pp.55-62
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• 2006

This paper presents experimental evaluation of an insect-mimicking flapping-wing device actuated by a unimorph piezoceramic actuator. Length of each rod and hinge point in the linkage/amplification system are carefully chosen such that the resulting wing motion can mimic clapping of wings in a real insect at the end of upstroke. In addition to this, a pair of corrugated wings are fabricated mimicking zig-zag cross section of a real insect wing. Thanks to the two additional implementation, the improved flapping wing device can generate a larger lift force than the previous model even though area of the new wing is about 50% less than that of the previous wing. In this work, effects of the wing clapping, the wing corrugation, and the input wave form on the lift force generation have been also experimentally investigated. Finally, the vortex generated by the flapping device has been captured by a high speed camera, showing that vortices are produced during up- and down-strokes.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1998.10a
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• pp.20-20
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• 1998

풍력발전용 회전날개의 구조설계 요구조건은 크게 제한 강도 요구조건(Limit strength requirement), 강성도 요구조건(Stiffness requirement), 피로수명 요구조건(Fatigue life requirement)의 세 가지를 들 수 있다. 첫째로 제한 강도 요구조건은 운용기간 중에 발생할 수 있는 최대하중에 견딜 수 있어야 하며, 폭풍이나 돌풍의 상황에 대한 안전성을 의미한다. 둘째로 강성도 요구조건은 운용 중 공진을 피하기 위한 고유진동 수확보, 타워와의 충돌을 피하기 위한 변위의 제한, 공력성능의 변화를 피하기 위한 비틀림각의 제한등이 있다 셋째로 피로수명에 대한 요구조건은 요구피로수명 동안에 예상되는 반복하중에 견딜 수 있어야 한다.

• 한국신재생에너지학회:학술대회논문집
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• 2008.10a
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• pp.328-331
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• 2008

For the purpose of verifying the calculation, the rotor blade shall be subjected to test for the natural frequencies and the static loading within the scope of the assessment. This paper presents a full scale static test procedure of the rotor blade for certification by GL. This blade model is manes as KM24 designed for IEC type IA. The test and calculation values are all most similar. Also there is not founded any marks of cracks or buckling at the shell, and bonding area is T/E, L/E and shear web. Therefore, the test is successful and the rotor blade is satisfied the safety requirement at the maximum design load.

• Journal of the Korea Institute of Military Science and Technology
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• v.6 no.4
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• pp.63-72
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• 2003

This paper deals with the analysis of composite sabot of APFSDS projectile. Unlike conventional composite parts, the sabot is composed of thick-sectioned lamination, and thus requires 3-dimensional properties in the analysis. In this study, a model was formulated to calculate the equivalent composites properties. The equivalent properties were then used in the finite element analysis and the results were compared with those by the full 3-dimensional analysis with ply-by-ply modeling. The results generally agreed with each other in the bound of 20% error, indicating that the formulated model produced the equivalent properties with reasonable accuracy. It was thought to be an efficient approach to use the model in global analysis and then perform the full 3-dimensional analysis in regions of interest for detailed evaluation in designing the composite sabot structure.

• Composites Research
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• v.30 no.5
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• pp.280-287
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• 2017

The complex deformation of the swept composite wing occurs due to the torsional load and bending load during the flight. Therefore, prediction for displacement of swept composite wing is required for structural health monitoring. Wing displacements can be predicted by using relationship between displacements and strains. The strain distributions on the fixed-end are complex due to the geometric shape of the swept wing. Because of those strain distribution, the wing displacement can be diversely predicted by the strain sensing locations. In this paper, displacements prediction of swept composite wing was performed by considering complex strain distributions. The predicted displacements under various loading condition were consistent with those calculated by FEA and verified through the bending test.