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首页> 外文会议>International Conference on Fracture and Strength of Solids >Influences of Crack Face Bridging Stress and Microstructure on Fracture Toughness of Toughened Alumina Ceramics
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Influences of Crack Face Bridging Stress and Microstructure on Fracture Toughness of Toughened Alumina Ceramics

机译：裂纹面桥接应力和微观结构对钢化氧化铝陶瓷骨折韧性的影响

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Three types of polycrystalline alumina, one pressureless and two hot press sintered Al_2O_3, were used to examine the effects of the characteristics of microstructure and crack face bridging on fracture toughness. The crack opening displacements and microstructures along the pop-in crack of single edge precracked beam (SEPB) specimens were observed in situ at a constant applied stress intensity factor by scanning electron microscopy (SEM). The bridging stress distribution could be determined from the measured crack opening displacement by three-dimensional finite element analysis, and then the stress intensity factor and stress shielding effect at the crack tip could also be determined. Intergranular microcracks of toughened Al_2O_3 were deflected by a complicated microstructure, and crack closure due to bridging grains was observed near the crack tip. Bridging stress of Al_2O_3 was compressive perpendicular to the crack face and was distributed behind the crack tip. The maximum bridging stress of two hot press sintered Al_2O_3 was about twice as large as that of pressureless sintered Al_2O_3. The fracture toughness of hot press sintered Al_2O_3 was, therefore, higher than that of pressureless sintered Al_2O_3, because the total amount of bridging stress and stress shielding effect increased with increasing magnitude of microcrack deflection and the number of interlocking grains.
机译：三种类型的多晶氧化铝，一个无压和两个热压烧结Al_2O_3，用于检查微观结构和裂纹面桥接对断裂韧性的特性的影响。通过扫描电子显微镜（SEM）在恒定施加的应力强度因子处原位观察沿着单边缘预焊光束（SEPB）样本的弹出式裂缝的裂纹开口位移和微观结构。通过三维有限元分析可以从测量的裂缝开口位移确定桥接应力分布，然后还可以确定裂纹尖端处的应力强度因子和应力屏蔽效果。增韧的晶间微裂纹由复杂的微观结构偏转，并且在裂纹尖端附近观察到由于桥颗粒引起的裂纹闭合。 Al_2O_3的桥接应力垂直于裂缝面压缩，并分布在裂缝尖端后面。两个热压烧结Al_2O_3的最大桥接应力大约是无气烧结Al_2O_3的两倍。因此，热压烧结的Al_2O_3的断裂韧性高于无气烧结Al_2O_3的骨折，因为桥接应力和应力屏蔽效果的总量随着微裂纹偏转的幅度和互锁颗粒的数量而增加。

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