Fatigue characteristics of stainless steel pin-reinforced composite hat joints

Effective use of metallic Z-pins for composites' through-thickness reinforcement

“…Z-pins most commonly take the form of thin pre-cured carbon fibre rods, inserted into an uncured pre-preg laminate. Metallic Z-pins are the most commonly used Z-pin type after composite Z-pins [1]- [6]. Metallic Z-pins differ from carbon-fibre through-thickness reinforcements because of their capacity to absorb large amounts of fracture energy via plastic deformation.…”

“…Metal Z-pins tend to have poor interfacial properties with composite materials, therefore surface treatments are necessary to ensure high fracture toughness under Mode I loading [1]- [3]. In the literature, aggressive surface treatment techniques such as targeted forging on the Z-pin surface and aqua regia solutions have been investigated to increase the bond strength of metal Z-pins with the laminate [1], [2]. Organosilane-coupling agents have also been shown to be effective at improving Mode I delaminations through the formation of polar bonds [3].…”

Fatigue behaviour of composite–composite joints reinforced with cold metal transfer welded pins

“…Thus, many research groups have investigated the effect of reducing these stress peaks with through-the-thickness reinforcements [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. Among these are stitched [1,[3][4][5]20], tufted [2] and z-pin reinforced [6][7][8][9] composite-composite joints.…”

“…Among these are stitched [1,[3][4][5]20], tufted [2] and z-pin reinforced [6][7][8][9] composite-composite joints. More recent studies focussed on the use of metallic rods as joining reinforcement [10][11][12][13][14][15][16][17][18][19]. Metallic reinforcements can, in contrast to polymeric yarns, glass or carbon fibres, add to the damage tolerance of the joint by plastic deformation [11,16].…”

“…The results indicate an increased damage tolerance of CFRP to CFRP joints compared to unreinforced SLS specimens. Results from literature show that through-the-thickness reinforcements can increase the fatigue life of SLS joints [1,10,13,18,20,[30][31][32][33][34]. The most common way to present the fatigue behaviour of SLS joints is a correlation of stress to numbers of cycle at failure, the so-called S-N curve [1,13,18,[30][31][32][33][34].…”