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정성욱(S.W. Jung),김용환(Y.H. Kim),남현욱(H.W. Nam),한경섭(K.S. Han) 대한기계학회 2002 대한기계학회 춘추학술대회 Vol.2002 No.5
The compressive behavior of fiber/particle hybrid metal matrix composites(MMCs) was studied. The<br/> fiber/particle hybrid MMCs were fabricated by a squeeze casting method. Al2O3 short fiber and particle were<br/> used as reinforcements and A356 aluminium alloy was used as a matrix. The fabricated MMCs were T6 heat<br/> treated, then tension and compression tests were conducted. The optical micrographs were taken to analyze the<br/> fiber orientation and the fracture behavior. Test results show that the tensile strength of the hybrid MMCs<br/> increases as the particle volume fraction increases. In compression tests, the fiber/particle hybrid MMCs<br/> shows an anisotropic behavior. The compressive strength of P-direction is much higher than that of N-direction.<br/> Microscopic observations show that major fiber breakage mode is buckling in P-direction and bending in<br/> N-direction. This is due to the difference of fiber orientation and the hybrid effects between fiber and particle.
이용태(Y.T. Lee),남현욱(H.W. Nam),송정일(J.I. Song) 대한기계학회 2002 대한기계학회 춘추학술대회 Vol.2002 No.5
Residual strength of fiber metal laminates after impact was studied. 3/4 lay up FML was fabricated by<br/> using 4 ply prepreg, 2 ply aluminum sheets, and 1 ply steel sheet. Quasi isotropic ([0/45/90/-45]s) and<br/> orthotropic ([0/90/0/90]s) FRP were also fabricated to compare with FML. Impact test were conducted by<br/> using instrumented drop weight impact machine (Dynatup, Model 8250). Penetration load and absorbed<br/> energy of FML were excellent than those of FRPs. Tensile test were conducted to evaluate the residual<br/> strength after impact. Strength degradation of FML was smaller than that of FRP. This means that the damage<br/> tolerance of FML is excellent than that of FRP. Residual strength of each specimen was predicted by using<br/> Whitney and Nuismer Model. Average stress criterion and point stress criterion were used to calculate the<br/> characteristic length. The characteristic length is assumed as constant. The distribution of characteristic length<br/> shows that the assumption is reasonable. Prediction was well matched with experiment.