This study aims at investigating the fracture characteristic according to the shape of the double cantilever beam specimen for mode II with ultra-high strength steel and Mg alloy steel. As the analysis, all three models had the left-hand holes that were constrained by the cylindrical support and the right-hand holes were enforced by the constraint condition of 6mm/min. This study result showed that the shorter the load block of the double envelope test specimen, the higher the safety. The results of this study are thought to be useful for examining the fracture characteristics of specimen for mode II with ultra high strength steel and Mg alloy steel.

Recently, the light weight and the safety of automobile are the important targets of automotive design and the parts for car have been substituted the plastic or the porous material for the steel material. As the aluminium foam has many pores at its surface, it has the fatigue property of bonded face which differs from general material. In this study, two dimensional model is designed and performed with the fatigue analysis as the variable(θ value) becomes the slant angle of bonded face at the specimen with the aluminium foam. As the analysis result on the models with the slant angles of 6°, 8° and 10°, the bonding forces are disappeared when the fatigue loads are repeated during 4000 cycle, 4500cycle and 5000cycle respectively. By comparing with the analysis results of three models, the fatigue cycle to endure fatigue load becomes larger as the slant bonded angle becomes higher. So, the structural safety can be seen by applying only as only a simulation of finite element method instead of the experiment where much cost and time is spent. In this study, the configuration of aluminum foam is designed with the shape of TDCB Mode II. The shear fatigue strength of the bonded structure can be evaluated by the analysis program of ANSYS.

Tapered double cantilever beam (TDCB) specimens are the most commonly used test configurations to measure the fracture toughness of composites and adhesive joints. The material used in this study is aluminum alloy. For the impact analysis, load and displacement applied from pin onto end block as well as the crack energy release rate are calculated and compared with the finite element analysis results. The energy release rate increases with the velocity increases. As TDCB model with the same condition as experiment is simulated and analyzed, the fracture behavior can be estimated with the analysis result similar to experiment. The simulation results can be agreed with experimental graph and all experimental data at this study can be verified. These experimental results can be applied into real field effectively. It is found that the energy release rates measured from impact tests on the specimens can be predicted by the finite element model suggested in this study.

알루미늄 폼을 볼트나 너트를 이용하여 체결한다면 경량성이 감소되므로 접착제로 접합하는 것이 가 장 효율적이다. 이런 알루미늄 폼 접착 구조물에 대한 충격 피로 특성과 접착 합면에 대한 파괴인성 연 구는 매우 부족하며 또한 중요하다. 이에 따라 본 연구에서는 알루미늄 폼으로 만들어진 DCB모델을 접 착제로 접합한 후 두께를 변수로 하여 25mm 부터 45mm까지 10mm차이를 두어 실험과 컴퓨터 시뮬레 이션을 통하여 수행하였다. 실험은 MTS사의 인장 시험기를 사용하여 강제 변위 100mm를 주어 변위에 따른 전단력을 알아보았고, 실험과 똑같은 조건하에 ANSYS를 이용하여 유한요소해석을 수행하였다. 실험과 유한요소해석 값을 비교하여 접착제로 접합된 알루미늄 폼 구조물의 접착 합면에 대한 파괴인성을 고찰하였다.

이중외팔보 모델은 일반적으로 복합재료의 구조테스트와 접착 접합의 테스트에 많이 쓰인다. 본 연구 에서 쓰인 재료는 알루미늄 합금2014이다. 또한 접착 구조물의 접착 면에서 발생한 에너지 해방율 및 유한요소해석을 통하여 알루미늄의 충격에 대한 기계적 특성을 알고자 하는 것이 목적에 있다. 상단부와 하단부의 접착 부위는 하중 점으로부터 100mm 떨어지도록 예비크랙을 두어 접착을 하도록 설계하였다. 하중은 핀에 Y축 방향으로 작용하였다. 충격속도는 7. 5m/s와 12.5m/s로 가하였다. 충격속도가 12.5m/s 일 때의 에너지 해방율은 약 7500J/m2으로 나왔다. 충격 속도가 빠를수록 하중 핀에 가해지는 하중이 증가된다는 것을 알 수 있었으며, 에너지 해방율도 높게 나타나는 것을 알 수 있었다.

Aluminum foam as porous material in wide use has the excellent mechanical and thermal properties. As adhesive process technique is used by bonding such composites as aluminum foam, fracture toughness at adhesive joint is the main point to investigate. In this study, DCB specimens are manufactured to evaluate the strengths at adhesive joints on the basis of British industrial and ISO international standards. Four kinds of specimens are made by changing the height of the specimen and these experimental results are compared with each other. Energy release rates are also calculated at mode I. As the hight of specimen becomes higher, reaction force and energy release rates become higher. Through the correlation obtained by this study result, aluminum foam material bonded with adhesive can be applied to the real composite structure and mechanical property and fracture toughness are analyzed systematically.

Aluminum foam with the property as the excellent impact absorption has been widely used recently. It is necessary to study fracture energy due to fracture toughness by the use of adhesive joint at aluminum foam. This study aims at strength evaluation about adhesive joint on aluminum foam and the fracture of bonded DCB model with this material property is analyzed by simulation. These models are designed by differing in height on the basis of British industrial and ISO standards. As the value of height at model is higher, bonded part is separated to the end. By comparing some analysis results with experimental data, these data could agree with each other. By the verification with experimental results, these all simulation results in this study can be applied on real composite structure with aluminum foam material effectively. The fracture behavior and mechanical property can also be examined by this study.