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Multiscale Simulation for a Crack Behavior in Heterogeneous Materials
누룰 파토니,권오헌,Fatoni, Nurul Fajriyah,Kwon, Oh Heon The Korean Society of Safety 2017 한국안전학회지 Vol.32 No.4
Functionally Graded Materials (FGM) as advanced heterogeneous composite materials have a higher performance than a conventional composite or bimaterial composite under some severe environments. As a heterogeneous material, FGM is commonly used in spacecraft, defense, nuclear and automotive industries due to its excellent properties. The purposes of this study are to evaluate the stress distribution and crack behaviors by the multiscale simulation. FGM contains two or more than two materials that the composition is structured continuously. Two types of FGM model are suggested, which are created by arbitrary prediction of the volume fraction and the exponential function. Aluminum as the metal matrix constituent and silicon carbide as the ceramic particle constituent are structured gradually by two types and the three point bending test also estimated. Moreover, two kinds of crack location were introduced in order to get the influences of material property distribution on the stress intensity factor. From the results we found that the stress intensity factors are increased in the case from softer to stiffer material, while vice versa.
박우림,Nurul Fajriyah Fatoni,권오헌 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.5
To facilitate the widespread use of fuel cell vehicles, it is necessary to ensure the safety of high-pressure hydrogen storage vessels. Because the composite layer experiences the highest internal pressure, cracks in the carbon fiber reinforced plastic (CFRP) layer of type III high-pressure vessels directly affect their safety. In this study, we evaluate the crack behavior in a type III high-pressure hydrogen vessel using a ply modeling method and the extended finite element method. The failure criteria were determined from the maximum principal stress and displacement that exceed the allowable tensile strength, considering the fiber and the transverse directions of each ply. The weak point of the CFRP composite layers was in the transverse direction on the 17th ply at a helical winding angle of 35° in the boundary of the dome and the cylinder. The crack extension was resulted from exceeding the allowable transverse stress at 35° winding angle. These results may be valuable for ensuring the safety of high-pressure hydrogen vessels.