Pull-out testing of multiscale structured metallic z-reinforcements for CFRP laminates

• Published in: Composite structures Vol. 161; pp. 384 - 392
• Main Authors: Juergens, Michael, da Silva, Manuel Tiago von Hafe Pérez Ferreira, Heimbs, Sebastian, Lang, Holger, Ladstaetter, Elisabeth, Hombergsmeier, Elke
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.02.2017
• Subjects: Carbon fiber reinforced plastics; Energy absorption; Laminates; Mechanical properties; Morphology; Nanostructure; Polymer-matrix composites (PMC); Scanning electron microscopy; Surface chemistry; Surface properties; X-ray photoelectron spectroscopy; z-Reinforcements; Surface properties; Mechanical properties; Polymer-matrix composites (PMC); z-Reinforcements
• ISSN: 0263-8223; 1879-1085
• DOI: 10.1016/j.compstruct.2016.11.060

A testing method is presented to determine the pull-out behavior of interleaving metallic z-reinforcements for carbon fiber reinforced polymer (CFRP) laminates and joints. Energy absorbing mechanisms are described with respect to the metallic materials and means of surface pretreatment applied. Mechanical, wet-chemical and physical pretreatments result in milli-, micro- and nanoscaled oxide morphologies of titanium and stainless steel surfaces. Both, a high macro roughness of the reinforcement surface and a low difference in thermal expansion with regard to the surrounding CFRP is clearly proven to feature the highest level of energy absorption during pull-out tests. Surface analyses through scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) indicate laser-induced nanostructure’s scale and morphology to provide good adhesion properties but not to allow macroscopic friction between metal surface and epoxy resin.