The mechanics of z-fiber reinforcement

In-plane properties of composite laminates with through-thickness pin reinforcement

“…1 While they gave no quantitative information on the elevation in delamination resistance imparted by z-pins, they suggested that some degradation of the in-plane properties will occur. Barrett (1996) performed axisymmetric and three-dimensional finite element analysis of the delamination behaviour of carbon fibre-epoxy z-pins in a carbon fibre-epoxy laminate, including the effects of thermal expansion mismatch. Grassi et al (2002) performed finite element computations of z-pinned reinforced laminates to determine in-plane moduli in tension and compression, and found that the knockdown in modulus was 7-10%.…”

Influence of through-thickness reinforcement aspect ratio on mode I delamination fracture resistance

“…The shape of the resin layer is controlled by the hole diameter, whereas it is different from the zpinning process, where the resin pool is developed in the cavity that forms around a z-pin when it penetrates into the prepreg and pushes fibers aside to produce the ''cat eye geometry''. The resulting elliptic shape cavity is filled with resin of the native laminate during the consolidation and cure process [4,8,26].…”

A Fundamental Investigation into the Deformation and Failure Behavior of Heterogeneous Materials with the Aim of Developing Design Guidelines

“…For short rod reinforcements, various metallic (aluminum and titanium), or fibrous carbon rods with diameter between 0.2-0.6 mm are inserted through the thickness of the laminate (Barrett, 1996, Rugg et al, 1998. The area density of reinforcement is between 1-5 %.…”

“…Therefore, drawing on the biological experience, we developed the helicoidal architecture to build a laminated carbon-fiber epoxy-matrix composite. However, since interlaminar strength is still governed by the matrix material, the delamination 8 resistance must be increased by using through-thickness reinforcement (Barrett, 1996;Rugg et al, 1998Rugg et al, , 2002Mouritz et al, 1997aMouritz et al, , 1999; these reinforcements increase the load capacity, and prevent initiation and propagation of delamination cracks. The z-stapling reinforcement with an appropriate pattern was evaluated and implemented in this work as described in detail later in this report.…”