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Gil-do Jeong(정길도),Mynul(마이눌),Amkee Kim(김엄기) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11
The solid particle erosion behaviour of unidirectional carbon fiber reinforced plastic (CFRP) composites was investigated. The erosive wear of these composites was evaluated at different impact angles (30°,45°,60°,90°), different impact velocities (40, 55, 60,70㎧) and at three different fiber orientations (0°,45°,90°). The erodent used was silica sand with the size range 50-100㎛ of irregular shapes. The result showed ductile erosion behaviour with maximum erosion rate at 30° impingement angle. The Fiber orientations had a significant influence on erosion. The erosion rate displayed a strong dependence on impact velocity which followed the power law E∝V<SUP>n</SUP> for all materials. Based on three factors impact velocity(V), impact angle(α) and fiber orientation angle(β) a general method was proposed to predict the erosion rate of unidirectional fiber reinforced composites.
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.
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.