A STUDY ON DYNAMIC BEHAVIOR OF <font>C</font><font>f</font>/<font>SiC</font> COMPOSITES

The dynamic behavior for the fabrication of carbon fiber reinforced SiC matrix composites( C f / SiC ) is investigated by the theory and experiment. The governing differential equation of a composite beam is derived via Hamilton&#39;s principle. The C f / SiC composites have been fabricated by a liquid phase sintering process, using the ultra-fine SiC particles and oxide additive materials. The SiC based materials are fabricated by using a commercial SiC powder with an average size of about 0.3&#181;m. An Al 2 O 3- Y 2 O 3- SiO 2 powder mixture is used as a sintering additive. The compositional ratio ( Al 2 O 3/ Y 2 O 3) and its total amount ( Al 2 O 3+ Y 2 O 3) of additive materials are 1.5 and 10 wt%, respectively. Especially, the content of PVB is changed from 0 wt% to 10 wt%. The SiC based materials are sintered at the temperature of 1820&#176;C under 30 MPa for 1 hr. In this study, the effect of content of PVB on the natural frequency and mode shape is obtained. Finally, the relationship between natural frequency and mechanical property of C f / SiC composites is discussed.