Experimental and numerical methods to analyse deformation and damage in random fibrous networks

Deformation and damage behaviours of random fibrous networks are investigated with experimental and numerical methods at local (fibre) and global (specimen) levels. Nonwoven material was used as an example of fibrous network, with its individual fibres were extracted and tested with a universal testing system in order to assess their material properties. The fibres demonstrated a nonlinear time-dependent response to stretching. For analysis of notch sensitivity, undamaged nonwoven specimens and those with various notch shapes were analysed with fabric-level tensile tests and finite-element simulations. A level of strains around notch tips was tracked in simulations, demonstrating that the material was notch-sensitive, but load-transfer mechanisms were different than those in standard homogeneous materials. The notch shape also affected the rate of damage growth in the main directions. A good agreement between experimental and numerical damage patterns was observed. Also, the notch shape affected the strength and toughness of the fibrous network.