Dipartimento di Scienza dei Materiali e Ingegneria Chimica, Politecnico di Torino, Torino, Italy.
Langmuir. 2011 Nov 1;27(21):12822-33. doi: 10.1021/la2024549. Epub 2011 Sep 28.
The distribution of stresses in rigid colloidal aggregates under a shear flow was investigated numerically for particle-cluster and cluster-cluster aggregates with fractal dimensions ranging from 1.7 to 2.3. stokesian dynamics was used to calculate the hydrodynamic force on each monomer, while the internal intermonomer interactions were calculated by applying force and torque balances on each primary particle. Although the hydrodynamic forces act mainly on the periphery of the clusters, their filamentous structure propagates and accumulates internal stresses toward the inner region of the aggregates, where consequently the most loaded intermonomer bonds are located. The spatial stress distribution, when scaled by the proper power of the radius of gyration, is independent of aggregate size and fractal dimension. This feature has made it possible to identify the most probable locations of bond failure in the structure and to estimate the relationship between shear rate and particle size for the occurrence of restructuring and of breakage.
刚性胶体聚集体在剪切流下的应力分布进行了数值研究，研究对象包括具有分形维数 1.7 至 2.3 的颗粒-簇和簇-簇聚集体。斯托克斯动力学用于计算每个单体上的流体动力，而内部单体间相互作用则通过对每个初级粒子施加力和扭矩平衡来计算。尽管流体动力主要作用于聚集体的外围，但它们的丝状结构会向聚集体的内部区域传播和积累内部应力，从而导致最受力的单体间键位于此处。当用适当的转动半径幂次对空间应力分布进行缩放时，它与聚集体尺寸和分形维度无关。这一特征使得能够识别结构中最有可能发生键失效的位置，并估计在发生重构和断裂时剪切率与颗粒尺寸之间的关系。
