• Structural Engineering and Mechanics
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• 제65권3호
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• pp.243-250
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• 2018

The use of blast hardened bulkheads (BHBs) is an effective vulnerability hardening technique for improving the survivability of naval warships when internal explosions occur due to being shot by an anti-surface missile. In this paper, a new concept of BHBs reinforced by aluminum (Al) foam is proposed. The new concept can significantly reduce the blast pressures transferred to bulkheads and, unlike conventional BHBs, can be easily installed to operating naval warships. Chamber model blast tests were performed to demonstrate the effectiveness of the Al-foam BHBs and the results are further supported by numerical simulations. Finally, a practical preliminary is proposed for the Al-foam BHBs.

• 소성∙가공
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• 제11권8호
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• pp.701-709
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• 2002

Aluminium foam material is highly porous material, which has the complicated cellular structure defined by randomly distributed pores in metallic matrix. This structure gives the characteristic properties which cannot be achieved by any other conventional processes. As the properties of aluminium foam material significantly depend on its porosity, a desired profile of properties can be tailored by changing the foam density. But various defects lead to undesirable effects on the mechanical properties. Mechanical properties are dependent on cell sizes and aspect ratios. Therefore, this paper presents the effects of various processing parameters of various parameters on the mechanical properties. For the sake of this, combined stirring was used to fabricate aluminum foam materials by the parameters. Compression and bending tests were performed to investigate the effects of cell sizes and aspect ratios on the mechanical properties.

• 에너지공학
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• 제15권1호
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• pp.60-66
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• 2006

발포 알루미늄이 삽입된 환형관에서의 유동과 대류 열전달 특성을 실험적 연구를 수행하여 분석하고 heat sink로서의 실현 가능성을 검토하였다. 다른 기공밀도를 갖는 두 종류의 발포 알루미늄을 사용하여 유동과 열전달 특성을 파악하고 마찰계수와 열전달 관련 Nusselt수를 Darcy 수, Reynolds수, Prandtl수의 함수로 상관식을 구하였다. 발포 알루미늄이 없는 경우에 비해 마찰계수는 증가하지만 Nusselt수에서도 6에서 10배의 증가를 나타낸다. 따라서 열교환기의 크기가 제한되는 경우 열교환기에 발포알루미늄을 삽입하면 전열면적을 감소시킬 수 있으므로 열교환기를 소형화할 수 있다.

• Steel and Composite Structures
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• 제51권1호
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• pp.53-61
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• 2024

Aluminum foams sandwich panel (AFSP) has been used in engineering field, where cyclic loading is used in most of the applications. In this paper, the fatigue life of AFSP prepared by the bonding method was investigated through a three-point bending test. The mathematical statistics method was used to analyze the influence of different plate thicknesses and core densities on the bending fatigue life. The macroscopic fatigue failure modes and damage mechanisms were observed by scanning electron microscopy (SEM). The results indicate that panel thickness and core layer density have a significant influence on the bending fatigue life of AFSP and their dispersion. The damage mechanism of fatigue failure to cells in aluminum foam is that the initial fatigue crack begins the cell wall, the thinnest position of the cell wall or the intersection of the cell wall and the cell ridge, where stress concentrations are more likely to occur. The fatigue failure of aluminum foam core usually starts from the semi-closed unit of the lower layer, and the fatigue crack propagates layer by layer along the direction of the maximum shear stress. The results can provide a reference for the practical engineering design and application of AFSP.

• 한국공작기계학회논문집
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• 제15권1호
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• pp.113-118
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• 2006

In this work, we observed the changes in mass difference according to Al-foam's amount of Ca contents which depends on the viscosity control of fusion, quality of foamed addition, mixing, temperature tests. These are crucial influencing factors in determining foam-metal's size in the manufacturing process. In order to obtain the specimen, we changed the specific gravity from 0.2 to 0.3 for the study of the light weight, and obtained the optimal values of specific gravity, and then showed the mechanical characteristics of ultra-lightweight metal according to the changing mass. The optimal conditions for aluminum foam is when the addition of Ca content in $1.5wt\%~2.0wt\%$

• 한국주조공학회지
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• 제27권1호
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• pp.36-41
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• 2007

Compressive properties of the open cell 6063 aluminum alloy foams made by the plaster molding process were investigated before and after heat treatment. Loading process was controlled at a displacement rate of 2 mm/min. Compressive strength of 10 PPI foam was the largest of the same density foams. Increase in strength after heat treatment for the bulk material was remark able, however was not for the 6063 aluminum foam. C values were in the range of $0.39{\sim}0.53$ for as cast foams and $0.13{\sim}0.16$ for T6 heat treated foams in the equation of ${sigma}^*_{pl}/{\sigma}_{ys}=C({\rho}/{\rho}_{s})^{1.5}$ and increased with cell size.

• 한국자동차공학회논문집
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• 제11권3호
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• pp.155-160
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• 2003

For the weight reduction of vehicle body up to 20∼30% compared to the conventional monocoque steel body·.in-white, most automotive manufacturers have attempted to develop the aluminum intensive body-in-white using an aluminum space frame. In this paper, the crush tests and simulations for the aluminum extrusions filled with the structural from are performed to evaluate the collapse characteristics of that light weighted material. From these studies. the effectiveness of structural for is evaluated in improving automotive crashworthiness. In order to improve the improve energy absorption capability of the aluminum space frame body, safety design modifications are performed and analyzed based on the suggested collapse initiator concepts and on the application of the aluminum extrusions filled with structural foam. The effectiveness of these design concepts on the frontal and side impact characteristics of the aluminum intensive vehicle structure is investigated and summarized.

• 대한기계학회논문집B
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• 제26권6호
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• pp.883-892
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• 2002

A numerical study has been carried out to investigate the flow and heat transfer from an aluminum foam heat sink in a confined channel. A uniform heat flux is given at the bottom of the aluminum foam heat sink, which is horizontally placed on the heated surface. The channel walls are assumed to be adiabatic. Cold air is supplied from the top opening of the channel and exhausted to the channel outlet. Comprehensive numerical solutions are acquired to the governing Wavier-Stokes and energy equations, using the Brinkman-Forchheimer extended Darcy model and the local thermal non-equilibrium model f3r the region of porous media. Details of flow and thermal fields are examined over wide ranges of the principal parameters; i.e., the Reynolds number Re, the height of heat sink h/H, porosity $\varepsilon$and pore diameter ratio $R_{H}$.

• 한국산학기술학회논문지
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• 제13권4호
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• pp.1488-1495
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• 2012

본 논문에서는 알루미늄 폼 복합재료로 된 DCB(이중외팔보) 시험편의 파괴 거동을 시뮬레이션 해석하였다. 시뮬레이션 해석에 사용된 모델은 영국 공업규격과 ISO국제규격에 의거한 3D 형태로 하였다. 모델의 두께가 두꺼울수록 발생한 크랙의 길이가 길게 나타났고, 높은 하중이 발생하였다. 본 연구에서 얻어진 해석 결과를 알루미늄 폼재질로 접합된 실제 복합재 구조물에 적용시켜 파괴거동을 분석하고 그 기계적인 특성을 파악할 수 있다.

• 한국주조공학회지
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• 제28권2호
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• pp.79-84
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• 2008

Metal foam is one of the most interesting materials with various multi-functional properties such as light weight, energy absorption, high stiffness and damping capability. Among them, energy absorption property has keen interests in the field of automotives for passenger protection. Nowadays, researches about pore size and porosity control of the foam are increased to correspond them. However, though energy absorption properties are improved, these results are not cost-effective process. In present research, however, as a part of improving the energy absorption property of metallic foams, 606X aluminum alloy was used for cell wall material which has higher strength than pure aluminum. And its morphological features are characterized. As a results, porosity and pore size are uniformity distribution with increasing foaming temperature in the case of 6061 alloy foams. 6063 alloy foam specimens have opposite tendency because of the influence of alloying element and viscosity of the molten melt.