On the Relationship of Fracture Energy to Fiber Debonding, 1999 International Paper Physics Conference Proceedings

Heikki Kettunen, Kaarlo Niskanen

We present a microscopic model for both the spatial distribution of microscopic damage along a fracture line and for the energy consumption in the fracture process. Damage refers to bond failures and other microscopic ruptures that can be made visible using silicone impregnated specimens. The model assumes that all fibers crossing the fracture line may either debond completely or fail. The network geometry suffices in reproducing measured distributions of damage across the fracture line. When fiber failures are absent and inter-fiber bonding reasonable, microscopic damage can be seen in a zone whose width is equal to two fiber lengths. Fiber failures decrease the width of the damage zone. When modeling the fracture energy we assume that the fiber debonding process propagates stochastically from the fracture line towards fiber ends. Fiber failures are allowed during the process but they are assumed to consume no extra energy compared to the debonding of a fiber end. When plotted against the width of the damage zone, the predicted fracture energy is consistent with a variety experimental results taken from previous studies.