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다공성 알루미늄 합금이 충진된 스테인레스 강 원통 Shell의 제조 및 굽힘거동
김엄기(Amkee Kim),이효진(Hyo-Jin Lee),조성식(Seong-Seock Cho) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.4
Potential applications of foam-filled section are the automotive structures. A foam-filled section can be used for the front rail and firewall structures to absorb impact energy during frontal or side collision. In the case of side collision where bending is involved in the crushing mechanics, the foam filler will be significant in maintaining progressive crushing of the thin-walled structures so that more impact energy can be absorbed. In this study, the manufacturing process of closed cell aluminum alloy foam filled stainless steel tube was studied, and the various foam filled specimens including piecewise fillers were prepared, tested and discussed about the bending behaviors.
Study on Compressive Behavior of Heterogeneous Al-alloy Foam by Cruciform-Hemisphere Model
Amkee Kim(김엄기),Kazi Tunvir(카지 턴비르),Sung-Jun Park(박성준),Gil-Do Jeong(정길도),Hasan(하산),Seong-Sik Cheon(전성식) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5
Compressive behavior of closed cell aluminum (Al) alloy (Al-Si-Ca and Al-Si-Cu-Mg) foams having an isotropic material property was investigated by finite element (FE) analysis of a multiple lattice finite element model composed of cruciform and hemispherical sections. Different wall thickness for the hemisphere and the cruciform sections were considered in the model on the basis of micro structural examination of real foam. The simulation for Al-Si-Ca foam being ductile showed a good agreement with the experiment in the entire deformation range. However Al-Si-Ca-Mg foam being brittle in nature showed less resistance to the large deformation compared to the simulation.
김엄기(Amkee Kim),전용두(Yong-Du Chun),이금배(Kum-Bae Lee),김창훈(Chang-Hoon Kim),남승훈(Seung-Hoon Nahm) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.4
The erosion behavior of artificically aged HK40 steel was investigated. Erosion tests were conducted at room temperature, 200℃ and 400℃ using Al₂O₃particles. Erosion rates increased with increment of temperature. The maximum erosion rate appeared with the impingement angle of 30 degree. The erosion rate increased, reached the maximum at 1000 hours, and after that, decreased with heat treatment time. The mechanism of erosion seems to be the cutting wear which is very much associated with the strength of material. As results, the erosion rates were rather affected by the tensile strength and the strain hardening coefficient than the hardness and the yield strength. such changes of material properties would be caused by the change of micro-structure to the precipitation of carbide and the dissolution of solid element within matrix during the heat treatment.
Thickness Effect on Compressive Fatigue Behavior of Al-Si-Ca Alloy Foam
Ilhyun Kim(김일현),Mynul Hossain(마이눌),Amkee Kim(김엄기) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5
The compressive fatigue tests on the closed cell Al-Si-Ca alloy foams with two different thicknesses were performed using a load ratio of 0.1. The quasi-static and cyclic compressive behaviors were obtained respectively. The fatigue stress-life (S-N) curves were evaluated from the obtained cyclic compressive behaviors. S-N curves were presented for the onset of progressive shortening. It turned out that the fatigue strength showed higher value for the thicker foam and the onset of shortening of thinner foam took place earlier. The crushing was found to initiate in a single band which broadens gradually with additional fatigue cycles. Progressive shortening of the specimen took place due to a combination of low cycle fatigue failure and cyclic ratcheting.
Lower Control Arm 열연강 용접부의 피로수명
김일현(Ilhyun Kim),김엄기(Amkee Kim),이상훈(Sang-hoon Lee),강우종(Woo-jong Kang) 한국자동차공학회 2008 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
The objective of this study is to provide the input data for the prediction of life time of welded automotive suspension components. The welded SAPH 440 specimens were machined for the tensile and fatigue tests. The tensile and fatigue strengths were measured. As result, the fatigue strength of welded specimen turned out to be much lower than that of SAPH 440 without weldment. The fatigue fracture occurred at the heat affected zone along the welding line. In addition, stress-life (S-N) curve in terms of an equivalent stress along the welding line identified with S-N curve under uniaxial load.
전기전도도를 이용한 Al-Si-Cu-Mg 합금 폼의 기계적 압축 특성 평가
이창훈(Chang-Hun Lee),김엄기(Amkee Kim),하산(Md Anwarul Hasan),남승훈(Seung-Hoon Nahm),조성석(Seong-Seock Cho) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.4
Electrical conductivity of Al-Si-Cu-Mg alloy foams of various density produced in powder metallurgical method has been measured using two probe electrical conductivity measurement method. Compressive mechanical properties such as elastic modulus and plastic plateau stress of foams were evaluated from electrical conductivity using power law relation and scaling laws of foam properties. Uni-axial compression test was also performed. Experimentally measured elastic modulus and plastic plateau stress were compared with the values evaluated from electrical conductivity. The computed values were in good agreement with the experimental result.
A Numerical Study on The Three Point Bending Behavior of AluminumFoam Filled Stainless Steel Tube
Md Anwarul Hasan(하산),Amkee Kim(김엄기),Seong-Sik Cheon(전성식),Chang-Hun Lee(이창훈),Hyo-Jin Lee(이효진),Seong-Seock Cho(조성석) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.4
A comprehensive numerical study on the three point bending behavior of Aluminum foam-filled stainless steel tube has been performed. Aluminium alloy foams with various densities were produced and their mechanical properites were evaluated. Finite element(FE) analysis of three point bending test was performed to evaluate bending behavior of foam filled cylindrical structures. Results showed that foam filling offered remarkable increase of bending resistance and enhanced the crashworthiness of the structure. It turned out to prevent the inward fold formation at the compression flange, resulted into the multiple propagating folds and increased the load carrying capacity.