Loading...
2 results
Search Results
Now showing 1 - 2 of 2
- Mode II fracture toughness of carbon–epoxy bonded joints with femtosecond laser treated surfacesPublication . Ferreira Moreira, Raul Domingos; Oliveira, Vitor; Silva, Filipe Gonçalo Andrade Da; Vilar, R.; Moura, MarceloMode II fracture toughness of carbon–epoxy bonded joints considering laser treated surfaces was evaluated using the End-Notched Flexure (ENF) test. Four different surface preparations were performed using distinct processing conditions before bonding the specimen arms. The Resistance-curves of the fracture tests were obtained considering an equivalent crack length based procedure. The influence of the different surface treatments on the mode II fracture behaviour was assessed comparing the average values of the fracture toughness. It was verified that a laser treatment employing two interfering laser beams, which produces a complex multi-scale surface morphology free of contaminants, is the best surface preparation regarding higher values of the mode II fracture energy. A cohesive zone analysis was used aiming to validate the followed procedures. The excellent agreement obtained between numerical and experimental results reveals that the used techniques are sound.
- Influence of femtosecond laser treated surfaces on the mode I fracture toughness of carbon-epoxy bonded jointsPublication . Ferreira Moreira, Raul Domingos; Oliveira, Vitor; Silva, Filipe Gonçalo Andrade Da; Vilar, R.; Moura, MarceloThe influence of laser surface treatments on mode I fracture toughness of carbon fibre reinforced composites bonded joints is addressed in this work. Five different surface treatments considering several combinations of laser fluence and scanning speeds were applied prior to bonding of the adherents, aiming to increase the adhesion and, consequently, the fracture resistance of the bonded joint. Mode I fracture characterisation considering Double Cantilever Beam tests was subsequently performed to assess the influence of the several treatments on the critical fracture toughness under pure mode I loading. A suitable compliance based data reduction scheme was used to obtain the resistance curves as function of the equivalent crack length. It was verified that a laser treatment based on an interference scheme is the most effective surface preparation concerning maximization of the mode I fracture energy. A finite element analysis including cohesive zone modelling was performed to validate the procedure and experimental conclusions.