• Journal of Aerospace System Engineering
• /
• v.11 no.6
• /
• pp.17-25
• /
• 2017

Vertical reaction force between ground and tire is an important parameter determining the ground behavior characteristics of aircraft. This parameter can be used to calculate the lateral force and friction. However, it is hard to obtain this parameter in real-time when the aircraft is taxiing. Therefore, pre-analysis of ground behavior and vertical reaction force should be conducted using ground simulation results to prevent rollover or hazardous scenarios. In this paper, a Landing Gear and Full-Aircraft model was constructed using VI-Aircraft S/W. The roll behavior of aircraft was analyzed using steering simulation results compared with taxi-test data.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.38 no.3
• /
• pp.303-308
• /
• 2014

Aircraft are an indispensable mode of modern transportation. They are also used as in a wide variety of other fields. For example, aircraft are used for accommodating passengers, carrying freight, and for military reconnaissance. Aircraft ground operations include landing and taking off. During landing, a higher load is applied to the landing gear than during takeoff. The landing gear should absorb impact energy and prevent damage to the main body of the aircraft in the case of an accident. In this study, simulations were performed for two types of plate-spring-type landing gear: that made of composite materials and that constructed with aluminum. The structural safety of landing gear made of each material was also evaluated.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.39 no.4
• /
• pp.314-320
• /
• 2011

In this work, optimization of two-stage shock absorption system for lunar lander has been carried out. Because of complexity of impact phenomena of shock absorption system, a 1-D constitutive model is proposed to describe the behavior of shock absorption system. Quadratic polynomial regression meta-model is constructed by using a commercial software ABAQUS with the proposed 1-D constitutive model, and sequential approximate optimization of two-stage shock absorption system has been carried out along with the constructed meta-model. Through the optimization, it is verified that landing impact force on lunar lander can be considerably reduced by changing the cell size and foil thickness of honeycomb structure in two-stage shock absorption system.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.47 no.1
• /
• pp.26-34
• /
• 2019

In this paper, a coarse lunar soil model is developed using discrete element method and its computed physical properties are compared with those of the actual lunar soil for its validation. The surface of the actual moon consists of numerous craters and rocks of various sizes, and it is covered with fine dry soil which seriously affects the landing stability of the lunar lander. Therefore, in consideration of the environment of the lunar regolith, the lunar soil is realized using discrete element method. To validate the coarse model of lunar soil, the simulations of the indentation test and the direct shear test are performed to check the physical properties(indentation depth, cohesion stress, internal friction angle). To examine the performance of the proposed model, the drop simulation of finite element model of single-leg landing gear is performed on proposed soil models with different particle diameters. The impact load delivered to the strut of the lander is compared to test results.

• Composites Research
• /
• v.23 no.6
• /
• pp.26-31
• /
• 2010

This research work contributes to a study for the procedure and methodology to assess the fatigue durability for a composite torque link for helicopter landing gear, which was newly developed and fabricated by the resin transfer moulding technique to interchange with metal component. The simulated load spectrum anticipated to be applied to the torque link during its operation life was generated using an advanced method of probabilistic random process, and the fatigue durability was evaluated by the residual strength degradation approach on the basis of material test data. The full scale fatigue test was performed and compared with the analysis results.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.10
• /
• pp.459-467
• /
• 2019

The landing gear is a component that requires a high degree of safety to protect the lives of rotary-wing aircraft and boarding personnel, absorbing the impact on transfer/landing and supporting the fuselage during taxiing and mooring on the ground. In particular, the wheel landing gear supporting the aircraft fuselage absorbs most of the shock from the ground through the shock absorber and tires. This ensures the safety of the pilot on board the aircraft and satisfies the operational capability of the soldiers between missions. During the operation of a rotary-wing aircraft, a number of piston pins, which are a component of the right main wheel landing gear, were found to be broken. Therefore, this study examined the root cause of the piston pin crack phenomenon found in the main wheel landing gear. For this purpose, various causes were identified from fracture surface analysis of a flight test. In particular, the possibility of cracking was analyzed based on the influence on the fastening torque with the drag beam component applied to the piston pin at the time of development. This ensures the fatigue life and structural integrity.

• Proceedings of the Korean Institute of Industrial Safety Conference
• /
• 2003.10a
• /
• pp.101-106
• /
• 2003

항공기 외부 장착물인 POD는 전자전 방해장치(ECM, electronic counter measures)로서 전자방해 장비 및 부분 부품인 전ㆍ후방 러그(lug)와 외부 케이스로 이루어져 있다. POD는 항공기 외부 동체 하단부 및 파일런(pylon)에 장착되어 작동하므로 항공기의 운용중 이륙부터 착륙간의 기동에 의한 피로하중을 주로 받게 되므로 POD 부품들에 대한 구조 건전성 확보하기 위해서는 MIL-STD-1530의 요구에 따라 내구성(durability) 및 손상허용설계(damage tolerance design) 의 평가가 요구되고 있다.(중략)

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.33 no.5
• /
• pp.50-56
• /
• 2005

The objective of this study is to find the optimal thrust condition and wing loading of a vertical take-off and landing (VTOL) fixed-wing aircraft through a single engine failure analysis during landing approach and an analysis of transition flight. The aircraft analysis modules used in the study are based on the aircraft synthesis program. To achieve the computing infrastructure for aircraft design and analysis, the EMDIOS was employed as a design framework, which is a semi-completed application program and ready to customize. Simulation results reveal the most critical height at the event of single engine failure is approximately 40 ft. And, in order to avoid a significant loss in altitude during the transition, the thrust to weight ratio must be kept high, while both the engine tilt speed and the wing loading must be kept low, as confirmed by the analysis results.

• Journal of Aerospace System Engineering
• /
• v.14 no.1
• /
• pp.16-20
• /
• 2020

The fatigue happening during the road riding of the vehicle and for the moment the aircraft lands on the runway is closely related to the life cycle of the landing gear, the airframe, the vehicle's suspension, etc. The multiple loads acting on the wheel are longitudinal, lateral, vertical, and braking forces. To study the dynamic characteristics and fatigue stiffness of the vehicle, the dynamic fatigue simulator generally has been used to represent the real road vibration in the lab. It can save time and cost. In hardware, the critical factor in the hydraulic fatigue simulator structure is to decouple each axis and to endure several load vibration. In this paper, the inverse kinematic analysis method derives the magnitude of movement of the hydraulic servo actuator by the coupling after rendering the maximum movement displacement in the axial direction at the center of the dummy wheel. The result of the analysis is that the coupling between the axes is weak to reproduce the real road vibrations precisely.

• Composites Research
• /
• v.22 no.2
• /
• pp.30-36
• /
• 2009

In this paper, we propose the design method for the composite torque link of a landing gear for a helicopter. The composite torque link has to be light weighted and very stiff to keep the shock absorber in the landing gear of helicopter. The configuration and structural shape has to be designed in consideration of the RTM (Resin Transfer Molding) manufacturing process which is adopted to minimize the manufacturing cost. The mechanical properties are obtained through the coupon tests with the specimens made by the same manufacturing process for the composite structure. The optimal design process was performed through iterative modifications of the models which were verified by stress analysis using FEM. The composite torque link has lug-shaped parts and is very thick, so 3D Layered solid elements of ABAQUS were used to get the stress field including the stress components in thickness direction and non-linear static analysis using contact B.C. of rigid-deform condition was used to get the optimal design.