Growth Resistance R-curve Behavior in Transverse Fracture

Crack growth resistance (R-curve) behavior in transverse fracture 

The size of damage depends on fiber Ff, fiber aspect ratio, types of fiber and matrix material, bonding at the fiber-matrix interface, layup sequence in multi-angle ply laminates, specimen geometry including laminate thickness, and loading 

In short fiber composites, energy absorption mechanisms, such as interfacial debonding and matrix cracking, most often occur at the fiber ends (Curtis et al., 1978). The damage model proposed by Bader et al. (1979) assumes that short fiber composites fail over a critical cross-section which has been weakened by the accumulation of cracks, since the short fibers bridging this critical zone are unable to carry the load. In fatigue loading, sudden fracture takes place as a direct result from the far-field effect of the composite, rather than due to the near field of the crack tip 

It is assumed that the maximum stress in the next fiber located at a distance dj away is approximately equivalent to the composite tensile strength, cr. It follows then that the damage zone size, cq, for aligned short fiber composites is given by (Lauke et al., 1985) 

Agarwal, B.D. and Glare, G..S. (1982). Influence of the properties of the matrix material on the fracture toughness of short fiber composites. Mater. Sci. Eng. S2, 139-145. 

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