This study carried out passenger safety assessment by real car crash simulation of composite post structures for road facilities. The effects of different material properties of composites for various parameters are studied using the LS-DYNA finite element program for this study. In this study, the existing finite element analysis of steel post structures using the LS-DYNA program is further extended to study dynamic behaviors of the structures made of various composite materials. The numerical results for various parameters are verified by comparing different models with displacements and stress distribution occurred in the post and car.

This study carried out real car crash simulation of composite post structures for road facilities. The effects of different material properties of composites for various parameters are studied using the LS-DYNA finite element program for this study. In this study, the existing finite element analysis of steel post structures using the LS-DYNA program is further extended to study dynamic behaviors of the structures made of various composite materials. The numerical results for various parameters are verified by comparing different models with displacements and stress distribution occurred in the post and car.

This study analyzes performance-cost ratio of composite(GFRP) wind-towers by fiber reinforcement angle and determines their optimal fiber angle. The finite element models for composite structures using the ANSYS program described in this paper is attractive not only because it shows excellent accuracy in analysis but also it shows the effect of the geometrical combination. New results reported in this paper are focused on the significant effects of the cost for various parameters, such as thicknesses of outer shells and stiffeners. From the numerical examples, optimal fiber angles were determined as 80°∼90°.

This study carried out finite element deflection analysis of cylindrical shell structures made of composite materials, which is based on the micro-mechanical approach for different fiber-volume fractions. The finite element (FE) models for composite structures using multi-scale approaches described in this paper is attractive not only because it shows excellent accuracy in analysis but also it shows the effect of the material combination. New results reported in this paper are focused on the significant effects of the fiber-volume fraction for various parameters, such as fiber angles, layup sequences, and length-thickness ratios. It may be concluded from this study that the combination effect of fiber and matrix, largely governing the dynamic characteristics of composite shell structures, should not be neglected and thus the optimal combination could be used to design such civil structures for better dynamic performance.

본 논문에서는 앵커볼트의 체결력을 고려한 유한요소 모델을 제안함으로써 앵커볼트로 연결된 부재의 해석적 평가방법을 제안하였다. LS-DYNA를 사용한 유한요소 모델링은 복잡한 3차원 상세모델보다는 단순화된 앵커모델들을 적용함으로써 해석 효율성을 고려하였다. 앵커볼트는 Beam 혹은 Solid 요소로 토크 조임에 따른 앵커볼트 긴장상태를 반영하였고, 토크 조임에 따른 체결력을 고려하기 위해 너트면에 압축력을 도입하거나 너트를 Shell 혹은 Solid로 고려하여 작용 토크값으로 산정되는 체결력과 등가의 하중을 도입하였다. 외력 작용 시 체결력과 마찰력에 의한 앵커볼트의 하중전달은 nodal rigid 혹은 contact 조건으로 고려하였다. 체결력을 고려한 세 종류의 앵커모델을 적용한 해석결과, Model I과 Model III는 볼트 축력과 전단력이 매우 유사한 값으로 계산되었고, Model II의 경우, 볼트 축력과 전단력이 다소 과소평가되는 것으로 나타났다. Model I은 다른 두 모델에 비해 수치해석적으로 효율적인 것으로 분석되었다.

본 연구는 폭발에 의한 충격 하중이 작용하는 경우에 대하여 AFRP(KFRP)로 이루어진 벽체 구조의 화이버 보강각도 변화에 따른 방폭 성능 효과를 비교 제시하였다. 실제 폭발시험과 근사한 해석을 도출해내기 위해서 실제충격을 정확하게 묘사할 수 있는 구성 방정식과 상태방정식을 포함한 정교한 수치 시뮬레이션 해석을 수행하였다. 폭발에 의한 극한 충격하중과 같은 순간적인 동적인 문제를 해석하기 위하여 극도의 비선형성 해석과 고속충돌해석에 특화된 AUTODYN-3D 프로그램을 사용하여 화이버 보강 각도의 변화가 AFRP 벽체의 탄소성 거동에 미치는 영향을 상세 분석하였다.

The dynamic analysis of poles made of advanced composite materials is carried out for different length-thickness ratios and layup sequences. The numerical results using ABAQUS obtained for plates and shells are in good agreement with those reported by other investigators. The new results for laminated composite pole structures in this study mainly show the effect of the interactions between the radius-length ratio and other various parameters. The effect of fiber angles of long composite poles also investigated. Key observation points are discussed and a brief design guideline is given.

The method based on various mathematical characteristic equations for identifying tensile forces in the cable structure system are used as response data to reflect the properties of the dynamic sensitivity. The vibration tests have been conducted with respect to levels of applied weight for the sagged cable. In this study, a set of natural frequencies are extracted from the measured dynamic data. Next, existing characteristic equation methods based these extracted natural frequencies are applied to identify tensil forces of the sagged cable system. Through several verification procedures, the proposed methods could be applied to a sagged cable system when the initial material data are insufficiency.

This study deals with an enhanced assumed strain (EAS) three-dimensional element for free vibration analysis of laminated composite and sandwich structures. The three-dimensional finite element (FE) formulation based on the EAS method for composite structures shows excellence from the standpoints of computational efficiency, especially for distorted element shapes. Using the EAS FE formulation developed for this study, the effects of side-to-thickness ratios, aspect ratios and ply orientations on the natural frequency are studied and compared with the available elasticity solutions and other plate theories. The numerical results obtained are in good agreement with those reported by other investigators. The new approach works well for the numerical experiments tested, especially for complex structures such as sandwich plates with laminated composite faces.

This paper presents free vibration characteristics of laminated composite plates with different embedded delamination sizes and locations using three-dimensional finite elements. The free vibration analysis using the 3D finite element (FE) delamination model has merits in that it shows better accuracy but also shows the entire mode shape compared to the conventional approaches. This study investigates free vibration characteristics of laminated composite plates containing an various embedded delamination. The numerical results obtained are in good agreement with those reported by other investigators. Specifically, in this paper, attention is paid to the effects of the local vibration mode for various parameters, such as size of delamination, aspect ratio, and location of delamination.

본 연구에서는 고체요소를 사용하여 내재된 층간분리의 크기 및 위치 변화에 대한 복합소재 적층구조의 자유진동 특성을 분석한다. 본 연구에서 제시하는 3차원 유한요소 모델은 기존의 접근 방법에 비하여 정확성 뿐만 아니라 전 체 진동 모드를 보여준다는 점에서 장점을 갖는다. ABAQUS가 적용된 유한요소 모델은 다양한 내재된 층간분리를 포함하는 적층구조의 자유진동을 분석하기 위하여 사용되었다. 도출된 수치해석 결과는 기존의 연구결과와 비교하 여 잘 일치함을 보였다. 특히, 본 연구에서 제시한 결과는 층간분리의 크기, 길이-두께의 비율, 그리고 층간분리의 위치변화에 대하여 국부 진동 모드에 미치는 중요한 영향들에 대하여 초점을 둔다.