Cohesive zone model and slow crack growth in ceramic polycrystals
Cohesive zone model and slow crack growth in ceramic polycrystals
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陶瓷多晶中的内聚区模型和缓慢裂纹扩展
DOI：
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发表时间：
2009
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通讯作者：
C. Tallaron
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作者：
M. Romero de la Osa;R. Estevez;C. Olagnon;J. Chevalier;L. Vignoud;C. Tallaron
陶瓷多晶体受到缓慢裂纹生长（SCG）和环境辅助故障，类似于观察到的玻璃。已知断裂动力学取决于载荷水平、温度以及相对湿度（RH）。然而，有证据表明，当比较单晶与多晶的响应时，微观结构对SCG速率的影响与对裂纹前进的阻力的显着增加有关。后一种观察的起源的澄清促使了骨折的局部方法的发展。我们提出了一个基于物理的内聚区的描述，模仿反应破裂过程的SCG。我们提出了如何参与的内聚区配方中的参数可以确定捕获SCG在单晶。然后，我们提出了在一个二维平面应变多晶体沿晶破坏的模拟。三重结被证明是关键的抗裂纹扩展。在这些交界处的缺陷的存在和它们对裂纹扩展的影响，然后进行调查。我们还表明，该描述是能够捕获的过程冷却引起的损伤，从而提供洞察适当的温度烧结，例如。然后，本数值工具被认为是有价值的陶瓷断裂进行虚拟测试，以估计热以及机械载荷的限制，安全使用，以及适当的工艺条件。
Ceramics polycrystals are subjected to slow crack growth (SCG) and also environmentally assisted failure, similarly to what is observed for glasses. The kinetics of fracture are known to be dependent on the load level, the temperature and also on the Relative Humidity (RH). However, evidences are available on the influence of the microstructure on the SCG rate with a marked increase in the resistance to the crack advance when comparing the response of a single crystal to that of a polycrystal. The clarification of the origin of the latter observation motivates the development of a local approach of fracture. We propose a physically based cohesive zone description that mimics the reaction-rupture process underlying SCG. We present how the parameters involved in the cohesive zone formulation can be determined to capture SCG in a single crystal. We then present simulations of intergranular failure in a 2D plane strain polycrystal. The triple junctions are shown to be key in the resistance to crack growth. The presence of defects at these junctions and their influence on the crack propagation is then investigated. We also show that the description is able to capture the damage induced by the process cooling, thus providing insight of the appropriate temperature for the sintering, for instance. The present numerical tool is then thought valuable to perform virtual tests on ceramics fracture in order to estimate thermal as well as mechanical loads limits for a safe use as well as proper the process conditions.