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A Nanoindentation Based Study of Mechanical Properties of Al-Si-Cu-Mg Alloy Foam Cell Wall
Md Anwarul Hasan(하산),Amkee Kim(김엄기),Chang-Hun Lee(이창훈),Hak-Joo Lee(이학주),Soon-Gyu Ko(고순규),Seong-Seock Cho(조성석) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.4
Nanoindentation technique has been used to measure the mechanical properties of aluminium alloy foam cell walls. Al-Si-Cu-Mg alloy foams of different compositions and different cell morphologies were produced using powder metallurgical method. Cell morphology of the foam was controlled during production by varying foaming time and temperature. Mechanical properties such as hardness and Young's modulus were calculated using two different methods: a continuous stiffness measurement (CSM) and an unloading stiffness measurement (USM) method. Experimental results showed that hardness and Young's modulus of Al-5%(wt.)Si-4%Cu-4%Mg (544 alloy) precursor and foam walls are higher than those of Al-3%Si-2%Cu-2%Mg (322 alloy) precursor and foam walls. It was noticed that mechanical properties of cell wall are different from those of precursor materials.
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.
Compression-Compression Fatigue Behavior of Al-Si-Ca alloy Foams
이창훈(Chang-Hun Lee),하산(Md Anwarul Hasan),김엄기(Amkee Kim),정길도(Gil-Do Jeong) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.11
The compression-compression fatigue properties of the closed cell Al-Si-Ca alloy foams have been studied. The monotonic and cyclic compressive properties were compared with each other and the fatigue stress-life (S-N) curves were presented. In compression-compression fatigue, 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 which is in accordance with the findings of previous researchers [1-3]. Young’s modulus of the foam was found to decrease with the increasing strain in case of fatigue test however in case of monotonic compression test the value of Young’s modulus increased with the strain (number of cycles). The endurance limit on the basis of 107 cycles obtained by extrapolating the experimental results were 0.98 MPa and 1.70 MPa for load ratios 0.1 and 0.5 respectively which are 34 % and 59 % of the plateau stress.
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.