직접에너지적층 공정을 이용한 폐쇄형 알루미늄 폼 제작에 관한 연구

김화정,심도식 한국정밀공학회 2023 한국정밀공학회지 Vol.40 No.10

In this study, based on directed energy deposition (DED) technology, one of the additive manufacturing technologies, a porous material fabricated by mixing various aluminum alloys and foaming agent was manufactured. First, the foaming agent formed pores inside the deposited materials and differences in foaming characteristics were observed depending on the type of aluminum. Also, the foaming characteristics according to the laser power, which is a representative process variable, were analyzed. As a result, a closed-cell porous material with a maximum porosity at a laser power of 1,100 W was manufactured. Results of the compression test showed that the porous material made by the pores generated therein collapses to absorb energy, and the internal pores disappear to become high density. Therefore, Young’s modulus and yield stress were reduced by the pores inside the sample of pure aluminum and Al6063. However, it was found that the specific energy absorption, which is an advantage of the foamed materials, increased compared to non-porous materials. The findings of this study confirmed that it was possible to manufacture DED-applied foam materials using aluminum powder and a foaming agent.

CFRP 샌드위치 복합재와 알루미늄 폼 코어 CFRP 샌드위치 복합재에 대한 충격 파괴 연구

이정호,조재웅 한국기계기술학회 2016 한국기계기술학회지 Vol.18 No.2

In this study, the fracture property of impact absorption is investigated using the carbon fiber composite material. And this property is compared with the carbon fiber composite material with aluminum foam. Carbon fiber composite material has the high specific strength and rigidity and the superior durability and fatigue life and light weight. On the ground of these properties, this material hasbeen used widely at the fields of airplane, national defence industry, vehicle and the various industrial areas. Aluminum foam can also be applied at the various areas as it is the material with the superiorproperties. And this foam is the material which can solve the problem on the light weight of particular product. At the condition of the impact energy of 20J, the maximum loads of CFRP sandwich composite and CFRP sandwich composite with aluminum foam core are shown to be 5.7 kN and 6.5 kN respectively. In case of maximum energies, these values are shown to be 19 J and 17.5 J respectively. At the impact energy of 50 J, the maximum loads of CFRP sandwich composite and CFRP sandwich composite with aluminum foam core are shown to be 7 kN and 8.8 kN respectively. In case of maximum energies, these values are shown to be 43 J and 48 J respectively. At the impact energy of 80 J, the maximum loads of CFRP sandwich composite and CFRP sandwich composite with aluminum foam core are shown to be 9.2 kN and 11 kN respectively. In case of maximum energies, these values are shown to be 70 J and 63 J respectively. As the result of this study, the mechanical properties are investigated through the impact experiments on the composites composed of the closed aluminum foam and the carbon fiber reinforced plastic used frequently as absorbents.

Evaluation of Mechanical Properties of Al-Si-Cu-Mg Alloy Foams Using Electrical Conductivity

Kim, Amkee,Lee, Chang-Hun,Hasan, Md Anwarul,Nahm, Seung-Hoon,Lee, Hyo-Jin,Cho, Seong-Seock,Ahn, Byung-Wook 한밭대학교 생산융합기술연구소 2004 생산기반기술연구소 논문집 Vol.4 No.1

Closed cell Al-Si-Cu-Mg alloy foams of two different compositions (Al-5%Si-4%Cu-4%Mg alloy, Al-3%Si-2%Cu-2%Mg alloy) were produced using the powder metallurgy method. The electrical conductivity of the foams was measured. Uni-axial compression test was also performed on foams with different composition and different density. It is already well established that mechanical properties of Al-foam depend on its relative density while the power law equation for electrical conductivity of metal foam given by Ashby suggests that electrical conductivity of aluminium foam is a function of its relative density. Since the mechanical properties of Al-foam and its electrical conductivity are both function of relative density, so they can be expressed as a function of each other. In this paper mathematical relations have been derived to establish direct link between electrical conductivity and compressive properties of Al-Si-Cu-Mg alloy foams.

두께에 따른 알루미늄 폼의 파괴 특성에 관한 연구

고등(Teng Gao),조재웅(Jae Ung Cho) 대한기계학회 2015 大韓機械學會論文集A Vol.39 No.10

발포금속은 우수한 물리적 특성과 역학적 성능 때문에 많은 첨단기술 분야에 널리 사용되고 있다. 폐쇄형 알루미늄 폼은 발포금속 중에 하나이며, 우수한 충격에너지 흡수하는 성능 때문에 자동차와 항공기에 많이 쓰이고 있다. 본 연구에서는 폐쇄형 알루미늄 폼의 충격 실험을 통해 두께에 따른 기계적 특성을 분석하였으며, 검증으로 시뮬레이션 해석을 하였다. 시뮬레이션 해석 방법으로서는 ANSYS 를 이용하여 실험과 똑 같은 경계조건으로 유한요소해석을 진행하였다. 실험과 해석의 결과들을 비교해보면 10mm, 20mm, 30mm 인 경우에 20mm 인 경우는 제일 효율적인 것으로 사료된다. 20mm 의 경우가 시험편의 두께에 비하여 세가지 모델들의 경우에 있어 충격 에너지의 흡수가 가장 큰 것으로 나타났다. 본 연구의 결과들을 이용하면, 알루미늄 폼으로 된 기계 구조물의 개발에 필요한 자료를 제공할 수 있을 것으로 사료된다. Because foam metal has the excellent physical characteristics and mechanical performance, they are applied extensively into a lot of advanced technology areas. The aluminum foam with closed cell is one of the foam metals. It is applied widely into automobile and airplane because of the excellent absorption performance of impact energy. In this study, the mechanical characteristics by thickness was analyzed through the impact experiment of closed-cell aluminum foam, and the simulation analysis was performed for the verification. As the simulation analysis method, a finiteelement analysis was carried under the same boundary conditions as the experiment by using ANSYS. By comparing with the results of experiment and simulation, it was thought that the case of thickness of 20mm was the most efficient of among the cases of thicknesses of 10mm, 20mm and 30mm. At the case of thickness of 20mm, the absorption energy by comparing with the specimen thickness is shown to become the most among three models. By using the result of this study, it is thought that it can apply the material necessary to develop the mechanical structure with aluminum foam.

두께별 Mode Ⅲ 형의 TDCB 알루미늄 폼 접합시험편에 대한 피로 해석 및 검증

이정호,조재웅 한국기계기술학회 2015 한국기계기술학회지 Vol.17 No.5

Aluminum foam fits with the light material and has the superior physical and mechanical properties. On the other hand, if the aluminum foam is used arbitrarily without the study procedure, the user can be anxious about the damage of the mechanical structure applied with aluminum foam. By taking notice of this point, the aluminum foam specimens with the type of mode Ⅲ by thickness are designed and the analysis of fatigue fracture is carried out with ANSYS program. By this analysis result, the maximum load tends to increase as the thickness of spcimen increases. The experiment of fatigue fracture is carried out as this verification and the experimental data are shown to approach simulation data. Therefore, the simulation result data of this study are thought to be applied to the real structural design of aluminum foam. And the mechanical property of TDCB specimen with the type of mode Ⅲ under the fatigue loading condition is estimated to be analyzed systematically and effectively.

접합된 알루미늄 폼에서의 충격에 의한 비틀림 특성에 관한 연구

이정호,조재웅 한국기계기술학회 2015 한국기계기술학회지 Vol.17 No.4

As the property of the aluminum foam with porosity, the effect of impact is distributed through the distortion of each lattice like honeycomb at impact. So, this porous aluminum foam is widely used at the crash box or the impact absorber guard rail to prevent the damage. In addition, there is a property of low weight by the chemical bonding using the adhesive. As this study investigates the distortion property of the aluminum foam bonded with adhesive, the fracture property and the stress distribution of the bonded interface are examined. The specimen thicknesses are 25, 35, 45, 55 and 65 mm. And the torsional moments corresponding to 100, 200 and 300 J are applied at one side of bonded aluminum foam. The mechanical behaviors at the bonded interface and the fixed part are also investigated. It can be seen that the minimum specimen thickness must become 55 mm and over in order to maintain the bonding force due to the applied impact energy. The analysis result of this study at the bonded interface effected on impact can be effectively applied into the safe design of the structure with the bonded aluminum foam.

희생부재를 이용한 근거리 폭파압력 저감 효과

심창수,윤누리 한국지진공학회 2010 한국지진공학회논문집 Vol.14 No.1

주요 구조물의 방호를 위해 에너지 흡수 능력이 뛰어난 알루미늄 폼을 갖는 희생부재를 제안하였다. 근거리 폭발에 의한 집중된 폭파하중의 압력 저감에 대한 외연적 유한요소해석을 통한 변수 연구를 수행하였다. 폭발하중의 규모는 Z=0.48~0.95 수준으로 설정하였고 경험적 폭발하중을 이용하였다. 알루미늄 폼의 해석 변수는 밀도와 두께로 설정하였고 덮개 여부를 고려하였다. 해석 결과로 부터 밀도가 낮고 두께가 두꺼울수록 전달압력의 수준을 알루미늄 폼의 항복강도 수준으로 제어할 수 있고 폭발의 규모가 증가하면 높은 밀도의 두꺼운 희생부재가 필요함을 보였다. 덮개는 두께의 영향이 뚜렷하고 폭발압력을 분산시키는 효과를 나타내었다. 폭발의 수준에 따라 희생부재의 에너지 소산의 정도가 달라지기 때문에 이를 고려한 희생부재의 설계변수 설정이 필요하다. A sacrificial member with aluminum foam of excellent energy absorption capacity was proposed for the protection of significant structures. Parametric studies of explicit finite element analyses were performed to investigate the pressure mitigation of close-range air-blasts. The scaled distance of the blast had a range of Z=0.48~0.95 and an empirical blast load function was utilized. The analytical parameters of the aluminum foam were density, thickness and the existence of a cover sheet. Analytical results showed that the transmitted pressure can be controlled to have a similar level of yield values of the foam by using a foam with low density and higher thickness. As the blast load increased, the sacrificial member needed to have higher density and thickness. A cover sheet of the foam clearly showed its effect on the wider distribution of blast pressure. It is necessary to determine the design parameters of sacrificial foams considering different energy dissipation capacities according to the scaled distance.

이중외팔보 알루미늄폼의 파괴 거동에 관한 연구

방혜진(Hye-jin Bang),이상교(Sang-kyo Lee),조종두(Chongdu Cho),조재웅(Jae-ung Cho),최해규(Hae-kyu Choi) 대한기계학회 2012 대한기계학회 춘추학술대회 Vol.2012 No.11

Aluminum foam has developed in many commercial fields, especially transport machines division as a kind of porous metal. In this paper, Aluminum foam with the initial crack and closed cell form is used to take the axial load-time graph. It is fabricated with adhesively bonded DCB (Double Cantilever Beam) form and accordance with BS (British Standard) and ISO international standard. Using 10 kN Landmarks of MTS Corporation, 15 ㎜/min velocity of mode I shape is applied to aluminum foam specimen with displacement control method. And ABAQUS 6.10 is used to model and analyze the same model as a three dimension with same condition of experiment. Based on the result of axial load-displacement graph of experiment and image of that included of crack length depended on the time, energy release rate will be calculated and then the model is analyzed with this fracture energy condition. As a result, it is shown that different force aspect according to the displacement value and there is not big deformation in aluminum foam while Double Cantilever Beam get the force due to aluminum foam has bigger density and modulus than adhesive. Also, the similar maximum value is calculated using finite element method of cohesive element comparing with experiment.

접합된 알루미늄 폼에서의 충격에 의한 비틀림 특성에 관한 연구

이정호,조재웅 한국기계기술학회 2015 한국기계기술학회지 Vol.17 No.4

As the property of the aluminum foam with porosity, the effect of impact is distributed through the distortion of each lattice like honeycomb at impact. So, this porous aluminum foam is widely used at the crash box or the impact absorber guard rail to prevent the damage. In addition, there is a property of low weight by the chemical bonding using the adhesive. As this study investigates the distortion property of the aluminum foam bonded with adhesive, the fracture property and the stress distribution of the bonded interface are examined. The specimen thicknesses are 25, 35, 45, 55 and 65 mm. And the torsional moments corresponding to 100, 200 and 300 J are applied at one side of bonded aluminum foam. The mechanical behaviors at the bonded interface and the fixed part are also investigated. It can be seen that the minimum specimen thickness must become 55 mm and over in order to maintain the bonding force due to the applied impact energy. The analysis result of this study at the bonded interface effected on impact can be effectively applied into the safe design of the structure with the bonded aluminum foam.

두께에 따른 알루미늄 폼으로 된 Mode Ⅲ 형 DCB 시험편에 대한 전단 피로 해석 및 검증

고등,조재웅 한국기계기술학회 2015 한국기계기술학회지 Vol.17 No.3

As aluminum foam has the most superior absorption of impact energy, this material has been used at automobile and airplane. If aluminum foam is used by jointing bolt and nut, it can be broken. Therefore, it is more effective to bond aluminum foam and other materials by adhesive. In this study, the fatigue fracture simulation through ANSYS program is carried out on the aluminum foam specimen bonded with adhesive as the type of DCB Mode Ⅲ. There are four kinds of specimens with the types of DCB Mode Ⅲ in this study. The thicknesses of four specimens are 35mm, 45mm, 55mm and 65mm. In cases of specimen thicknesses of 35mm, 45mm, 55mm and 65mm, the maximum loads are shown as ±0.2kN, ±0.55kN, ±1kN and ±1.2kN respectively. As the specimen thickness increases, the maximum loads increase. The results of fatigue experiment as specimen thickness of 55mm can be shown to approach the simulation results by confirming the simulation results of this study. So, The simulation data can be applied in order to investigate the mechanical property at DCB specimen with the type of Mode Ⅲ.