Fracture mechanics analyses of ceramic/veneer interface under mixed-mode loading.
Fracture mechanics analyses of ceramic/veneer interface under mixed-mode loading.
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DOI：
10.1016/j.jmbbm.2014.07.019
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发表时间：
2014-11
影响因子：
3.9
通讯作者：
Gaoqi Wang;Song Zhang;Cuirong Bian;Hui Kong
中科院分区：
文献类型：
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作者：
Gaoqi Wang;Song Zhang;Cuirong Bian;Hui Kong
在牙科全瓷修复体中起重要作用的氧化锆/贴面双层结构的界面断裂性能研究较少。本研究的目的是评价氧化锆/单板界面在较宽的模式混合角范围内(相角0°~90°)的断裂力学性能，并考察材料和界面的力学性能对界面裂纹的起裂和裂纹路径的影响。提出了一种改进的含界面斜裂纹的夹层试验结构，并对其进行了标定，通过有限元分析选择了合适的几何尺寸。对不同界面倾角的试件进行了三点弯曲破坏试验。通过有限元分析得到了界面断裂参数。在界面断裂力学的基础上，采用三种裂纹扭结断裂准则来预测裂纹的萌生和扩展。此外，还研究了氧化锆板与单板热膨胀系数失配引起的残余应力对裂纹行为的影响。三种断裂准则均能很好地预测裂纹的萌生和扩展。对于相角为0的试件，裂纹在界面上扩展，而对于所有其他试件，裂纹在单板中弯曲。单板中的残余压应力可以提高界面结构的韧性。结果表明，在氧化锆/贴面双层结构中，贴面比界面弱，这可以用来解释临床上贴面碎片率大于界面剥离率的现象。因此，需要一种具有较大断裂韧性的贴面材料来降低全瓷修复体的失败率。并且基板的热膨胀失配系数可以更大，从而在单板中产生更大的压应力。
Few studies have focused on the interface fracture performance of zirconia/veneer bilayered structure, which plays an important role in dental all-ceramic restorations. The purpose of this study was to evaluate the fracture mechanics performance of zirconia/veneer interface in a wide range of mode-mixities (at phase angles ranging from 0° to 90°), and to examine the effect of mechanical properties of the materials and the interface on the fracture initiation and crack path of an interfacial crack. A modified sandwich test configuration with an oblique interfacial crack was proposed and calibrated to choose the appropriate geometry dimensions by means of finite element analysis. The specimens with different interface inclination angles were tested to failure under three-point bending configuration. Interface fracture parameters were obtained with finite element analyses. Based on the interfacial fracture mechanics, three fracture criteria for crack kinking were used to predict crack initiation and propagation. In addition, the effects of residual stresses due to coefficient of thermal expansion mismatch between zirconia and veneer on the crack behavior were evaluated. The crack initiation and propagation were well predicted by the three fracture criteria. For specimens at phase angle of 0, the cracks propagated in the interface; whereas for all the other specimens the cracks kinked into the veneer. Compressive residual stresses in the veneer can improve the toughness of the interface structure. The results suggest that, in zirconia/veneer bilayered structure the veneer is weaker than the interface, which can be used to explain the clinical phenomenon that veneer chipping rate is larger than interface delamination rate. Consequently, a veneer material with larger fracture toughness is needed to decrease the failure rate of all-ceramic restorations. And the coefficient of thermal expansion mismatch of the substrates can be larger to produce larger compressive stresses in the veneer.