1 results for Armeanu, Liviu Eduard

  • Analysis of bonded joints for small craft and marine applications

    Armeanu, Liviu Eduard (2010)

    Masters thesis
    University of Waikato

    This Thesis investigates the possibility of replacing, in small craft and recreative boats, some of the more traditionally made joints (using tabbing) with ones made using structural adhesives (adhesive used where the load applied may cause the separation of the adherends [2]), which have the potential to be quicker to produce and have good fatigue resistance. It also focuses on methods that are available to a small and medium size boatbuilding or boat design company in order to design and produce a general safe, light weight adhesive joint. Several static tests were conducted in order to identify the characteristics of the materials to be joined and the properties of the adhesives investigated. A summary of the analytical theories available in order to determine the characteristics of the joints are presented and compared, and several finite element models have been investigated in order to determine the suitability of this method when using adhesive materials. This Thesis focuses first on Single-Lap joints, not only as a joint, but also as a way to compare the characteristics of the adhesives to be used. Three types of adhesives have been tested, two commercially available (Plexus MA550 and Sikaflex 252) and one commonly found on boatbuilding yards, a mixture of vinyl ester and Epiglass HT120 (a silica based filler). It was found that the Plexus MA550 adhesive performed well across different substrates (aluminium and composites) followed closely in performance by the vinyl ester/filler mixture. Very promising results were obtained when a carrier fabric was used inside the adhesive layer. Secondly, a very common type of joint, the T-joint, has been anti - symmetrically tested. A comparison has been made between a more traditionally produced joint (using a small fillet made from vinyl ester and microballoons based filler and EU-glass tabbing) with a joint produced using a fillet made from the above adhesives. It was found that the results from samples with the fillet using the vinyl ester/filler mixture are the closest to the benchmark samples and it seems to be the best candidate to replace the traditional joint, given the strength, failure mode, price and the availability. The joint using a Sikaflex 252 fillet has shown the most interesting results such that none of the materials forming the joint suffered any visible damage after deformation. The joint using a R20mm Plexus MA550 fillet has benefited from the stiffness and the good adhesion characteristics of the adhesive but in all the tests the panels joined ware damaged earlier than for the benchmark samples.

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