Compressive damage of three-dimensional random fibrous ceramic materials: A meso-mechanics modeling and experimental study

Compression tests and corresponding simulations are performed to investigate the evolution (including damage, fiber-fiber contact, and compaction) of the microstructure of a transversely isotropic three-dimensional (3D) random fibrous (RF) material under compression along the through-thickness direction. A meso-mechanics model of the 3D RF material is built according to scanning-electron-microscope photographs and used for finite-element simulation. We consider two fiber failure modes: brittle fracture and instability. The fiber-fiber contact effect is a key aspect to be considered in simulating the mechanical behavior of a random fibrous network under compression. A new method for simulating the fiber-fiber contact effect is proposed that overcomes the disadvantages of the nonlinear-spring method. The trend of the simulated stress-strain curve agrees well with our experimental results. Progressive damage is found in the damage process, and we find a new damage mode: layer-by-layer damage. We find that the fiber-fiber contact process lags behind the damage process. We analyze the line density of 3D RF material in the damage process and find local compaction within the yield plateau. The formation mechanism of the yield plateau in the stress-strain curve is analyzed.