F. Kaya/Ceramics International 33(2007)279-284 Tensile 1 70 880 0,04 00x103 号110x0+-- 100x100 Strain Fig 3. Tensile test and AE results of the sample I which contains 30%o porosity approximately 1200 individual ceramic fibres with diameters of Tensile 1 10 um form bundles with an average overall thickness of 100x10 I mm) are much higher than tensile strength of un-reinforced mullite matrix, which is about 250-300 MPa and the thickness 10x10. Hence, high energy value acoustic events could be interpreted s 1x10 o acoustic events to be generated by the fracture of ceramic fibre bundles events are observed to be occurring towards to the end of the 100x103 Furthermore, high energy value(>10+ Joule x10-)acoustic g tensile loading, when energy values are plotted against the time 3 10x10 of the events, as shown in Fig. 6. These events could be ssociated with the fracture of the mullite fibre bundles. As both the thickness and the elastic modulus of the fibre mats are high, acoustic energy generated by the fracture of fibre mats are 100x100 expected to be higher[8 Fig. 7 shows the acoustic emission resp f the omposite labelled as sample 2 in Table 1. Co to the fig. 5. Acoustic emission ould be divided into two distinct categories which could be identified as "matrix related"and"fibre fracture related"events, if absolute energy values are plotted against amplitude values. 1000000 100000 a10000 罐 010203040 T Fig. 6. Acoustic events plotted against their time of event for sample 1 Fig. 4. Schematic illustration of shear movement of the fibre mats within the indicating that high-energy value hits occur towards the end of the tensileapproximately 1200 individual ceramic fibres with diameters of 10 mm form bundles with an average overall thickness of 1 mm) are much higher than tensile strength of un-reinforced mullite matrix,which is about 250–300 MPa and the thickness of the un-reinforced ceramic matrix layer is about 100–200 mm. Hence, high energy value acoustic events could be interpreted to be generated by the fracture of ceramic fibre bundles. Furthermore, high energy value (>103+ Joule 108 ) acoustic events are observed to be occurring towards to the end of the tensile loading, when energy values are plotted against the time of the events, as shown in Fig. 6. These events could be associated with the fracture of the mullite fibre bundles. As both the thickness and the elastic modulus of the fibre mats are high, acoustic energy generated by the fracture of fibre mats are expected to be higher [8]. Fig. 7 shows the acoustic emission response of the composite labelled as sample 2 in Table 1. Compared to the F. Kaya / Ceramics International 33 (2007) 279–284 281 Fig. 3. Tensile test and AE results of the sample 1 which contains 30% porosity. Fig. 4. Schematic illustration of shear movement of the fibre mats within the composite specimen. Fig. 5. Acoustic emission response of sample 1 indicating that acoustic events could be divided into two distinct categories which could be identified as, ‘‘matrix related’’ and ‘‘fibre fracture related’’ events, if absolute energy values are plotted against amplitude values. Fig. 6. Acoustic events plotted against their time of event for sample 1 indicating that high-energy value hits occur towards the end of the tensile loading.