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The effect of stress concentration on the compressive failure behavior of a carbon fiber composite laminate with an open hole is experimentally and numerically studied. The aspect ratio of the elli...

The interfacial strength between carbon fiber and phenolic resin is studied using molecular dynamics simulations to demonstrate that carbon fiber-reinforced carbon matrix composites (C/C composites) have improved tensile strength. Simulations are performed using two carbon fiber models, one of which has only carbon atoms and the other has carbon atoms and some fluorinated carbon groups. The carbon fiber models are regarded as two-layer graphite, and the phenolic resin model is treated as cross-linked structures. All force field parameters are based on the Dreiding force field. The tensile stress and interfacial fracture energy are calculated for the estimation of the interfacial strength. The results show that the model including the fluorinated carbon groups has lower interfacial strength than the model having only carbon atoms, up to a certain coating ratio of fluorinated carbon groups. Similarly, within the limits of the coating ratio, the interfacial fracture energy of the fluorinated carbon fiber mod...

In this study, we experimentally and analytically investigated time-dependent deformation of carbon-fiber reinforced plastic sandwich panels with three kinds of polymer foam-core ROHACELL, with the deformation caused by moisture absorption. Tensile tests for the ROHACELLs before and after moisture absorption were performed using the digital image correlation method, and we obtained a stress–strain relationship for each condition. Surface deformations of sandwich panels were calculated using finite element analyses to examine the elasto-plastic deformation of the ROHACELLs based on the tensile test results. Experimentally measured deformation in the sandwich panels varied depending on the cell size of cores, and the largest measured deformation after the moisture absorption was approximately 100 μm. This was much larger than the analytical result. On the basis of this study, we suggest that the main reason for the deformation may be an irreversible shrinkage of the ROHACELLs caused the absorption of moistu...

The effect of strain on the grain boundary characteristics and their correlation to mechanical properties is studied in detail in low carbon steel processed by warm multipass calibre rolling. It was noted that strength properties are controlled by the total grain boundary length but not grain boundary character or their fraction. On the other hand, impact properties are controlled by the length fraction of high angle grain boundaries. Finally, it was noted that low angle boundaries are found to be helpful in improving the strength whereas they are harmful for impact properties.

Accepted: 2002-10-28, 資料番号: SA1003311000