Development of a Simple Impact Testing Machine for the Characterization of Ceramic Fiber Reinforced Ceramic Composites

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1.The main purpose of this research project is to characterize the impact fracture behavior of some continuous fiber reinforced ceramic matrix composites (CFRC), and to develop a simple testing apparatus for measurement of impact fracture characteristics of some kinds of CFRC.2.Three point impact bending tests on CFRC were carried out using split-Hopkinson pressure bar method, and smooth transmittted stress waves without high-frequency fluctuation were obtained to evaluate dynamic stress-strain relationships precisely by applying ramped incident waives.3.Acoustic emission from the test specimen during the impact fracture was also successfully detected by applying a high-pass filter device on the data recording system.4.Tensile strength of a carbon fiber reinforced silicon nitride ceramic composite was found almost independent of deformation rate, while shear strength along the orientated fiber direction was significantly increased with increase of deformation rate. On the other hand, the tensile and shear strength of a Tirano fiber bonded ceramic composite markedly increased with increase of deformation rate and decrease of testing temperature.5.By using the basic data above described, an impact testing machine with simple and small scale was made on a trial basis, and the machine was also applied to obtain stress-strain relations during bending fracture of some CFRC.