Critical Stress of Microcracking in Alumina Evaluated by Acoustic Emission
Critical Stress of Microcracking in Alumina Evaluated by Acoustic Emission
复制标题
声发射评价氧化铝微裂纹临界应力
DOI：
10.1007/978-1-4615-3348-1_4
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发表时间：
1992
影响因子：
3.9
通讯作者：
H. Nishimura
中科院分区：
文献类型：
--
作者：
S. Wakayama;H. Nishimura
采用声发射技术评价了氧化铝陶瓷弯曲试验过程中的微断裂过程。使用不同尺寸的试样进行弯曲试验，以研究微断裂过程对试样尺寸的依赖性。在最终不稳定断裂之前，观察到每个样本的 AE 生成模式中的一个显着点，即 AE 事件和能量都迅速增加。重要的是，这些点处的表观应力与 AE 阈值水平和样本尺寸无关。使用荧光染料渗透剂方法，观察表面的断裂过程，然后可以理解，该应力对应于由于微裂纹和/或孔隙的合并而形成主裂纹的临界应力。考虑到微断裂过程，讨论了脆性材料强度的统计处理。因此，得出结论：临界应力可以作为陶瓷材料的高级评价参数，相当于金属的屈服强度。
Microfracture process during the bending tests of alumina ceramics were evaluated by acoustic emission technique. Different size specimens were used for the bending tests in order to investigate the dependence of microfracture process on the specimen size. A remarkable point in the AE generation pattern of each specimen, at which both AE events and energy increased rapidly, was observed before the final unstable fracture. It is important that the apparent stress at those points were independent of the AE threshold level and specimen size. Using the Fluorescent dye penetrant method, the fracture process on the surface was observed, then it has been understood that the stress corresponds to the critical stress for the maincrack formation due to the coalescence of microcracks and/or pores. Considering the microfracture process, statistical treatment for the strength of brittle materials has been discussed. Consequently, it was concluded that the critical stress can be the advanced evaluation parameter, which is equivalent to yield strength in metals, for ceramic materials.