Pramanik Brahmananda, Tadepalli Tezeswi, Mantena P Raju
Department of Mechanical Engineering, University of Mississippi, University, MS 38677, USA.
Materials (Basel). 2012 May 23;5(5):922-936. doi: 10.3390/ma5050922.
In this study, the fractal dimensions of failure surfaces of vinyl ester based nanocomposites are estimated using two classical methods, Vertical Section Method (VSM) and Slit Island Method (SIM), based on the processing of 3D digital microscopic images. Self-affine fractal geometry has been observed in the experimentally obtained failure surfaces of graphite platelet reinforced nanocomposites subjected to quasi-static uniaxial tensile and low velocity punch-shear loading. Fracture energy and fracture toughness are estimated analytically from the surface fractal dimensionality. Sensitivity studies show an exponential dependency of fracture energy and fracture toughness on the fractal dimensionality. Contribution of fracture energy to the total energy absorption of these nanoparticle reinforced composites is demonstrated. For the graphite platelet reinforced nanocomposites investigated, surface fractal analysis has depicted the probable ductile or brittle fracture propagation mechanism, depending upon the rate of loading.
在本研究中，基于三维数字显微镜图像的处理，使用垂直截面法（VSM）和狭缝岛法（SIM）这两种经典方法估算了乙烯基酯基纳米复合材料破坏表面的分形维数。在准静态单轴拉伸和低速冲剪载荷作用下，对石墨片增强纳米复合材料的实验破坏表面进行观察，发现了自相似分形几何特征。通过表面分形维数解析估算了断裂能和断裂韧性。敏感性研究表明，断裂能和断裂韧性与分形维数呈指数关系。证明了断裂能对这些纳米颗粒增强复合材料总能量吸收的贡献。对于所研究的石墨片增强纳米复合材料，表面分形分析描绘了可能的韧性或脆性断裂扩展机制，这取决于加载速率。
