배관시스템은 대표적인 사회기반시설이다. 지진으로 인한 배관 손상은 심각한 피해를 초래할 수 있으므로 배관시스 템은 지진으로부터 반드시 보호되어야 할 필요가 있다. 지진은 설계기준을 초과하는 상대변위를 동반할 수 있다. 이러한 지진의 거동은 배관 이음부에 손상을 줄 수 있다. 배관시스템에서 과도한 변형이 발생할 수 있는 위치에 지진분리이음을 적용하면 내 진성능을 향상시킬 수 있다. 적층형 금속 벨로우즈는 지진과 같은 저주기 피로 하중에 대한 내구성이 우수하다. 따라서 다중 적층 형 금속 벨로우즈는 파이프의 면진 이음새로 사용할 수 있을 것으로 판단된다. 본 연구에서는 지진분리이음의 하나인 다중 적 층형 금속 벨로우즈에 대한 실험적 연구를 수행하였다. 2종류의 다중 적층형 벨로우즈 신축관이음에 대하여 단조하중 및 반복 하중재하시험을 수행하고 손상모드와 한계상태를 추정하였다. 그리고 단조재하시험과 반복재하시험의 결과를 비교 분석하였다.

Light weighting is one of techniques considered importantly at designing the mechanical structure using the light weight material. This study deals with aluminum-6061 and aluminum foam which stood in the spotlight of light weight material. And the finite element method for safety evaluation has been carried out in order to prevent from the damage and fatigue fracture due to crack appearing at the mechanical structure with this material. The simulation analysis as MT(middle tension) test was carried out by using the core of aluminum foam and the material laminated with sandwich structure of Al-6061. The mechanical structure is linked together with various parts and designed as the material with hole or crack. So, MT test is one of the test methods to evaluate the fatigue fracture characteristic of material and the strength inside material with the center crack by applying the load to the part connected pin. The real material strength is thought to be evaluated through the study result of MT test analysis.

In order to provide the basis data for broad use and safe design of carbon fiber reinforced plastic, this paper aims at investigating the fracture behavior on CFRP specimen composed of one directional fiber through three point bending test. On the basis of experimental result, the improvement of composite layer specimen can be secured with the other data to compare the existing specimen. The fracture behavior happened at the experimental procedure is investigated in this study. The maximum loads of 1200 N, 1700N and 1600N are shown respectively at the specimens with the layer angles of 30°, 45° and 60°. The highest load is shown at the layer angle of 60° among all specimens and the longest displacement is maintained until each of the layer structure is broken down. The fracture due to the force applied from the outside can be prevented by applying the result of this study to the real structure. As structural safety can be evaluated and anticipated through this study, it is thought that the safe design is devoted.

In this study, the buckling restoration at CFRP 3-Point bending specimen composed of 30°, 45°and 60° is investigated when the pressure at the lowest position on the compressed specimen is eliminated. The fracture configuration and stress contour of the specimen can be seen according to the laminate angle of fiber. The result of this study is thought to apply the data for the safe design of CFRP structure.

CFRP hardened by carbon fiber and resin has the property of high strength and low weight. Specifically, the strong feature against the external vibration environment is shown as CFRP is designed with the structure of multi-axes. So, CFRP in place of metal has been used at the various fields. CFRP specimens for mode Ⅱ are applied with the repetitive fatigue load in this study. These specimens have the fiber layer angles of 30°, 45° and 60°. The material properties of specimens are investigated with the result of fatigue fracture due to this load. As the study result, the smallest and largest reaction forces of 500 N and 540 N are shown at the layer angle of 30° and 60° respectively among these specimens. The separation of adhesive interface at 4000 fatigue cycles is happened earliest in case of the layer angle of 60°. But the separation of adhesive interface at 11000 fatigue cycles is happened latest in case of the layer angle of 45°. Through the result of fatigue property, it is thought that the basis data can be applied to evaluate the safety at CFRP structure applied with fatigue.

As CFRP as the single material has various material properties, it has been used at many fields. CFRP is utilized at the mechanical structure on the basis of the brittle fracture property and the performance of vibration damping. CFRP composed of multiple axes has the high natural frequency. It is shown to have more reinforced material property with the fiber design. This paper investigates the fatigue property of the bonded specimen for mode 1 at the laminate angles of 30°, 45° and 60°. According to the fiber design, each specimen bonded with the laminate angle is shown to have different fatigue property repectively. As the laminate angle is increased, the reaction force tends to be increased. In this paper, the laminate angle through the fiber design of CFRP is applied and the fatigue property at mode 1 is investigated. Through the study result, The safety of fatigue fracture is also checked at applying to the composite structure.

Nowadays, the study of CFRP reinforced with carbon fiber is focused on improving the the mechanical property. The study on the fracture data of CFRP are not properly made out than that of the general mechanical joint. In this study, the fracture property of mode 1 at the same condition of tensile experiment is investigated by applying the layer angle to laminated CFRP with the thickness of 15 mm. When the reaction forces until dropping out the bonded surface are compared with the cases of the layer angles of 0°, 45° and 60°, the reaction force is shown to be most and the elapsed time until dropping out the bonded surface is longest at that of 45°. The deformation energy is also shown to have the highest value by dropping out the adhesive interface. As the basis of the analysis result of this study, the most safety with fracture resistance is shown in the case of 45°. the bonded structure applying the appropriate layer angle is thought to have the structural safety.

IAEA 및 국내의 방사성물질 운반 관련 규정에 따라 중·저준위 방사성폐기물 드럼 8개를 운반할 수 있는 IP-2형 운반용기를 개발하였다. IP-2형 운반용기는 낙하시험 및 적층시험을 거친 후 내용물의 유실 또 는 분산과 운반용기 외부표면에서의 방사선량률이 20 % 이상 증가할 수 있는 차폐능력의 상실이 없어야 한다. 본 연구의 목적은 적층시험조건에 대한 시험방법 및 절차를 수립하고 IP-2형 운반용기의 적층조건 에 대한 구조적 건전성을 평가하는데 있다. 운반용기의 원형시험모델을 이용하여 운반용기 중량의 5배 하중으로 24시간 동안 압축하는 적층조건에 대한 시험 및 전산해석을 수행하였다. 적층시험 시 운반용기 의 모서리기둥에서의 변형률 및 변위를 측정하였으며, 측정된 변형률 및 변위는 해석결과와 서로 일치하 였다. 컨테이너 바닥부의 처짐량은 측정이 어렵기 때문에 전산해석 방법으로 구하였다. 모서리기둥의 최 대 변위와 컨테이너 바닥의 최대 처짐은 법규에서 규정하는 허용치에 비하여 낮게 나타났다. 적층시험 전?후에는 운반용기의 외형치수, 차폐체 두께, 볼트토크 등을 측정하였으며, 그 값들을 비교분석한 결과 운반용기는 내용물의 유실 및 분산, 차폐체 두께의 감소가 나타나지 않았다. 따라서 적층시험조건에서 IP-2형 운반용기의 구조적 건전성이 입증되었다.

본 논문에서는 복합소재 방호울타리의 6가지 적층 단면에 대한 충돌시뮬레이션을 실시하여 최적 적층 단면을 결정하 였다. 먼저 6가지 단면 형상에 대하여 설문 조사를 통하여 형상을 결정하였다. 결정된 보 단면에 대하여 6가지 적 층설계를 하였다. 적층에는 CSM, DB, DBT, Roving 섬유를 사용하였다. LS-DYNA를 사용하여 수평 및 3:1 경사에 대한 복합소재 보를 모델링하였다. 직육면체 추 및 원통형 추를 사용하여 낙하 충돌 시뮬레이션을 실시하였다. 시뮬레이 션결과를 비교 분석하여 최적 적층 단면을 도출하였다.

본 연구에서는 수평전단시험을 통하여 LRB(lead-rubber hearing)의 동적 특성을 분석하였다. 10ton 및 200ton 용량의 LRB를 이용하여 수평전단시험을 수행한 결과 LRB의 동적 특성은 수평하중의 재하속도, 연직하중의 크기 및 전단변형률 등에 따라 크게 달라지는 것으로 나타났다. 세장비가 큰 면진장치에 과도한 변형을 가할 경우 내부 납심에 소성한지가 발생되어 납심이 파괴되는 것으로 나타났다. 따라서 면진구조물의 설계 및 해석 시에는 지진응답과 재하하중의 크기에 따라서 달라지는 LRB의 기계적 특성치를 적용하여 안전한 설계가 이루어질 수 있도록 하여야 한다.

As a result of abrasion resistance test of decoration wood-based flooring board laminated with PVC on plywood, compared to the flooring board laminated with general HPL surface decoration materials, it was available to secure far higher abrasion resistance. It seems to contribute to secure initial durability and maintenance of decoration wood-based flooring board as an important means, and it might be available for saving repair and maintenance costs due to flooring board issues.

In this paper, the tensile stiffness and deformation of laminated rubber bearing is investigated based on the research and test results. ISO 22762 and JIS K 6410 are not providing the tensile characteristics of rubber bearings. Besides, the tensile stiffness and deformation models are proposed by several researchers by quite different methods. Proper models are recommended for nonlinear deformation state in order to propose the tensile model and build up base data.

The fatigue is one of the key factors of long-lived design. For this study, wear & fatigue tests are carried out as per AASHTO Guide Specifications for seismic isolation design standard. In experiments, there was no appearance damage of the specimen. A study comparing test results before and after fatigue test showed that EDC & effective stiffness of the specimen after test is lower than before it.