Emerging anchored FRP systems bonded to steel subjected to monotonic and cyclic loading: A numerical study. (15th February 2022)

• Record Type: Journal Article
• Authors: Biscaia, Hugo C.; Micaelo, Rui
• Is Part Of: Engineering fracture mechanics. Volume 261(2022)
• Publication Date: 2022-02-15
• Subjects: Cyclic loading -- Hybrid bonded joints -- CFRP -- Steel structures -- Numerical simulations; Fracture mechanics -- Periodicals; Rupture, Mécanique de la -- Périodiques; Fracture mechanics; Periodicals; 620.112605
• DOI: 10.1016/j.engfracmech.2022.108250
• Languages: English
• ISSNs: 0013-7944

Abstract

Highlights: Forty eight different CFRP-to-steel bonded joints are modelled with DEM; The strength of short CFRP-to-steel bonded joints decreases upon cyclic loading; The smooth variable-width bonded strip performs better to improve strength; The global stiffness decreases with the number of cycles and is followed by the increase of the debonded length; The energy dissipation increases with the bonded length and fracture energy. Abstract: Recently, the study of the bond behaviour of hybrid joints has increased due to their application in different industries. Their main purpose is to obtain lightweight but strong, durable structures. In addition, in some industries such as the automotive industry, those requirements may facilitate the construction of vehicles that have lower carbon dioxide emissions. Although the knowledge on the bond behaviour of hybrid bonded joints under monotonic loading is sufficient, the knowledge on the cyclic bond behaviour needs to be improved. The present work aims to mitigate that gap by proposing a numerical model in which the cyclic bond performance between a Carbon Fiber Reinforced Polymer (CFRP) bonded to a steel substrate can be analysed. The results provided by the Externally Bonded Reinforcement (EBR) are used as reference data. These other simulated bonding techniques cover cases where the CFRP is anchored to the substrate in different ways, which are becoming more popular, namely by: (i) linearly increasing the width of the CFRP; (ii) using the mixed adhesive concept (two solutions were considered); (iii) using a steel plate on top of the CFRP strip; and (iv) assuming no interfacial slips at the CFRP unpulled end, which is intended to simulate a perfect anchorage. Compared to the simulations carried out under monotonic loading, the simulations with the adopted cyclic loading history (loading/unloading cycles), allowed us to observe a degradation of the bond strength of the joints with the number of cycles. However, if the overlapped bonded joint is long enough, the strength of the CFRP-to-steel joints is not affected. Excluding the numerical specimens with the perfectly anchored CFRP, i.e. with an "ideal" anchorage, the length of the other adopted anchorages affected either the strength or the ductility of the joint, whether subjected to a monotonic or to the adopted cyclic loading protocol.