Max Planck Institute for Dynamics and Self-Organization (MPIDS), 37077 Göttingen, Germany.
Soft Matter. 2017 Feb 7;13(5):1040-1047. doi: 10.1039/c6sm02600a. Epub 2017 Jan 13.
We study experimentally the fracture mechanisms of a model cohesive granular medium consisting of glass beads held together by solidified polymer bridges. The elastic response of this material can be controlled by changing the cross-linking of the polymer phase, for example. Here we show that its fracture toughness can be tuned over an order of magnitude by adjusting the stiffness and size of the polymer bridges. We extract a well-defined fracture energy from fracture testing under a range of material preparations. This energy is found to scale linearly with the cross-sectional area of the bridges. Finally, X-ray microcomputed tomography shows that crack propagation is driven by adhesive failure of about one polymer bridge per bead located at the interface, along with microcracks in the vicinity of the failure plane. Our findings provide insight into the fracture mechanisms of this model material, and the mechanical properties of disordered cohesive granular media in general.
我们通过实验研究了由玻璃珠组成的模型粘性颗粒介质的断裂机制，这些玻璃珠通过固化的聚合物桥连接在一起。例如，通过改变聚合物相的交联，可以控制这种材料的弹性响应。在这里，我们表明可以通过调整聚合物桥的刚度和尺寸来调节其断裂韧性。我们从不同材料制备下的断裂测试中提取出一个明确定义的断裂能。发现该能量与桥的横截面积呈线性关系。最后，X 射线微计算机断层扫描显示，裂纹扩展是由位于界面处的每个珠子上大约一个聚合物桥的粘附失效以及失效平面附近的微裂纹驱动的。我们的发现为这种模型材料的断裂机制以及一般无序粘性颗粒介质的力学性能提供了深入的了解。
