Concurrent use of Z-pins for crack arrest and structural health monitoring in adhesive-bonded composite lap joints

Effects of ferromagnetic & carbon-fibre Z-Pins on the magnetic properties of composites

“…Grigoriou et al [16] later extended the electrical-based applications of Z-pins to sandwich composites. In the research of Kadlec et al [17], Z-pins were found to effectively increase crack arrest ability of adhesive-bonded composite lap joints by 33% under static load. At the same time, the electrical resistance across pins was observed to have the same trend as crack growth, making this approach a promising candidate for structural health monitoring, thus supporting the certification of adhesive-bonded joints in aerospace applications.…”

“…More recently, there has been a strongly growing interest towards the exploration of multi-functionality in composites, in addition to load bearing functions. A number of studies have been published regarding the multi-functionality of Z-pinned composites [12][13][14][15][16][17][18][19][20].…”

Polyetherimide-Reinforced Smart Inlays for Bondline Surveillance in Composites

“…Various possible bondline defects such as disbonds, voids, cracks, foreign material inclusions, porosities, poor curing, and weak bonds, as well as sensitivity to environmental or physico-chemical conditions, make it challenging to ensure a certain level of adhesive strength [2,6]. Thus, critical primary bonded joints are still accompanied by additional fail-safe mechanical fasteners (sometimes referred to as chicken-rivets), which diminish the benefits of adhesive bonding [7][8][9]. Regulation authorities make clear requirements for certification of adhesively bonded joints whose failure would mean a catastrophic loss to the overall structure [10].…”

Experimental Investigation of the Effect of Adhesive-Impregnated Pins on the Mechanical Behavior of Z-Pinned Lap Shear Joints

“…In some studies, the use of z-pins for crack propagation arrest was examined [19,20]. Kadlec et al [21] studied the use of z-pins to arrest crack propagation across cracked lap shear (CLS) test specimens and found that the residual load after the crack propagation arrest was 250% of the limit load, which was safely tolerated by the z-pins, and the crack arrest capacity was 33% higher than the static limit load of reference joints without z-pins.…”