• Journal of the Korea institute for structural maintenance and inspection
• /
• v.6 no.3
• /
• pp.139-149
• /
• 2002

An explicit direct time integration method based solution algorithm is proposed to predict dynamic postbuckling response of thin plates. Based on the von Karman's plate equations and Marquerre's shallow shell theory, a rectangular plate finite element is formulated and utilized in this study. The element formulation takes into account geometrical nonlinearity and initial deflection of plates. The solution algorithm employs the central difference method. Using the computer program developed by the authors, dynamic postbuckling behavior of elastic thin plates under impact loading is investigated by considering the time variation of load and load duration. The efficiency of the proposed solution algorithm is examined through illustrative numerical examples.

• Aerospace Engineering and Technology
• /
• v.13 no.1
• /
• pp.20-26
• /
• 2014

In this paper, yield stress, tangent modulus and failure strain were varied to ascertain the influence of impact response such as impact force histories and residual energy. And the buckling behavior of FML(Fiber Metal Laminates) were analyzed using numerical method. A number of analyses on FML and aluminum panel were conducted for shear and compression loading to compare the capability of stability. And to evaluate the static performance, static analysis has performed for box beam structure. Low-velocity impact analysis has performed on FML made of aluminum 2024 sheet and glass/epoxy prepreg layers. And the buckling and static performance of FML have been compared to aluminum using the analysis results. For the comparison of structural performance, similar analyses have been carried out on monolithic aluminum 2024 sheets of equivalent weight.

• Computational Structural Engineering
• /
• v.9 no.3
• /
• pp.187-197
• /
• 1996

An explicit direct time integration method based solution algorithm is presented to predict dynamic buckling response of Euler column. On the basis of large deflection beam theory, a plane frame finite element is formulated and implemented into the solution algorithm. The element formulation takes into account geometrical nonlinearity and overall buckling of steel structural frames. The solution algorithm employs the central difference method. Using the computer program developed by the author, dynamic instability behavior of Euler column under impact loading is investigated by considering the time variation of load, load magnitude, and load duration. The free vibration of Euler column caused by a short duration impact load is also studied. The validity and efficiency of the present formulation and solution algorithm are verified through illustrative numerical examples.

• Journal of KSNVE
• /
• v.6 no.6
• /
• pp.735-747
• /
• 1996

In this paper, buckling reliability analyses of stiffened cylinder with random initial geometric imperfection under axial impact load are performed by the combined response surface method. The effect of random geometric imperfection on the failure probability and reliability is recognized quantitatively. Buckling reliability decreases with the increase of mean value, cov of initial geometric imperfection under the same external load. Buckling probability under impact load is greater than those under static load with the same condition. From the probabilistic characteristics of imapct buckling load, relation between reliability index and safety parameter can be obtained in addition to the relation between load and reliability index. And those results can be used to determine the range of required safety parameter and acceptable imperfaction.

• Computational Structural Engineering
• /
• v.10 no.1
• /
• pp.173-183
• /
• 1997

In this paper a method is suggested for the probabilistic analysis of impact buckling failure time of cylinder with random axisymmetric geometric imperfection under axial impact. Failure is assumed as axisymmetric radial deformation exceeds the given criteria for the first time. For the generation of random geometric initial imperfection, random field theory by mean function and autocorrelation function of geometric imperfection is used. Suggested method is useful for the treatment of the randomness of realistic geometric imperfection and can be used for the structural safety analysis of cylinder considering its effect.

• Proceedings of the KSME Conference
• /
• 2001.06a
• /
• pp.812-818
• /
• 2001

The drop type impact test and finite element analysis are established for examining the buckling behavior of a square tube under the lateral impact load. Based on these results, the effects by the boundary conditions for supporting the structure are reviewed, which are as follows. One is pinned condition by screw; the other is fixed by welding. The critical impact force and acceleration by test are nearly same between two cases. However, the critical impact velocity of the pinned condition is higher than that of the fixed case. Therefore, the dynamic buckling behavior of a pinned structure is better than the fixed condition in view of critical impact velocity. These test and analysis results will be adaptable for predicting the dynamic structural integrity of a tube structure not only the axial impact event but the lateral impact event.

• The Bulletin of The Korean Astronomical Society
• /
• v.37 no.2
• /
• pp.193.2-193.2
• /
• 2012

달착륙선 등과 같은 특수 목적을 위해 제작된 우주용 착륙선에는 착륙 시 전달되는 충격하중이 탑재장비로 전달되지 못하도록 연착륙(soft-landing)을 위한 충격흡수 메커니즘이 구현되어 있어야 한다. 일반적으로 자동차 및 항공기에서는 실린더와 피스톤으로 구성된 유공압식 완충장치를 주로 사용하여, 피스톤 압축으로 실린더 내부 오일 또는 압축공기가 오리피스를 통하여 분출됨에 따라 유체마찰 에너지를 활용한 충격 흡수장치가 일반적이다. 그러나 이와 같은 지상 장비용 유공압식 충격흡수 메커니즘은 진공 및 무중력 우주 환경하에서 오리피스 기능 상실, 유압유 기화 현상 및 극저온/고온 환경에서의 성능저하 등의 문제점으로 인하여 우주용 착륙선 충격완충장치로 적용이 불가능하다. 따라서 기존의 우주용 착륙선의 대부분은 충격에너지를 기계적인 좌굴 소성 변형에너지로 변환하여 충격을 흡수할 수 있도록 알루미늄 허니콤을 주로 많이 사용하여 왔다. 본 연구에서는 진공 및 무중력 우주환경에서 착륙선 충격완충 장치로 적용이 가능하도록 실리콘 포옴과 스프링을 조합하여 구성하였으며, 충격완충 매체로 유압유 및 공압을 대체할 수 있도록 실리콘 포옴을 후방 사출 성형 방식으로 적용하여 오리피스를 통과한 실리콘 포옴의 변형에너지로 충격에너지를 흡수하게 함으로서 착륙 완충효율을 극대화 할 수 있도록 검토하였다.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.5 no.4
• /
• pp.48-69
• /
• 1997

The use of advanced composite materials in many engineering structures has steadily increased during the last decade. Advanced composite materials allow the design engineer to tailor the directional stiffness and the strength of materials as required for the structures. Design variables to the design engineer include multiple material systems. ply orientation, ply thickness, stacking sequence and boundary conditions, in addition to overall structural design parameters. Since the vibration and impact strength of composite cylindrical shell is an important consideration for composite structures design, the reliable prediction method and design methodology should be required. In this study, the optimum design of composite cylindrical shell for maximum natural frequency, buckling strength and impact strength are developed by analytic and numerical method. The effect of parameters such as the various composite material orthotropic properties (CFRP, GFRP, KFRP, Al-CFRP hybrid), the stacking sequences, the shell thickness, and the boundary conditions on structural characteristics are studied extensively.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 1999.04a
• /
• pp.221-225
• /
• 1999

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.28 no.2
• /
• pp.414-421
• /
• 2022

Subsea oil and gas exploration is increasingly moving into deeper water depths, and typically, subsea pipelines operate under high pressure and temperature conditions. Owing to the difference in these components, the axial force in the pipe is accumulated. When a pipeline is operated at a high internal pressure and temperature, it will attempt to expand and contract for differential temperature changes. Typically, the line is not free to move because of the plane strain constraints in the longitudinal direction and soil friction effects. For a positive differential temperature, it will be subjected to an axial compressive load, and when this load reaches a certain critical value, the pipe may experience vertical (upheaval buckling) or lateral (snaking buckling) movements that can jeopardize the structural integrity of the pipeline. In these circumstances, the pipeline behavior should be evaluated to ensure the pipeline structural integrity during operation in those demanding loading conditions. Performing this analysis, the correct mitigation measures for thermal buckling can be considered either by accepting bar buckling but preventing the development of excessive bending moment or by preventing any occurrence of bending.