Optimization of steel-composite marine structures

To improve stability and functionality of a ship by reducing and re-distributing its weights, to make management of ship much more cost-effective, to protect its hull form the harmful impacts of marine environment, constructing steel ship?s superstructure by using Fibre Reinforced Polymer based composites (FRP) has been found very wide application area in today?s shipbuilding industry. This experimental study aiming to contribute the related efforts which the industry pays a lot of importance has been focused on the bonding performance of two materials which have very different properties: steel and FRP.To determine the reliability of bonding of these two materials, it is necessary to study on the fracture failure mechanism on the interface of the related materials. Considering this very critical failure for laminated materials, E-glass/epoxy composites and shipbuilding steel bonding?s performance has been measured under Mode I, Mode II and single-lap adhesively bonded joints? tensile loading conditions as the case studies.Strain energies as the measures of the performance have been calculated under three different loading conditions, for three roughness values of steel surface namely SA0, SA1 and SA2.5 and for two epoxy products of different producers. To minimize test errors, five specimens for each system have been produced. So, totally 90 tests have been performed.From the results obtained from the tests and the calculations, it has been concluded that:?The surface roughness of steel has a significant effect on the bonding performance of such kind of materials combination.?These tests can be used as a quality assurance tools for epoxy products.,?The strength of interfaces under shear loads (Mode II) are much more higher than which under tensile loads (Mode I).?The performance of the resin can be improved by using the undercoat materials in an economical way.?For the reduction of Mode I data, Area Method is much more advisable than Modified Beam Theory Method.?To evaluate steel ? FRP adhesive joints? performance Mode II test could not be found adequately useful because of the differentiation of the related materials? properties and behaviors.?Instead of Mode II test, tensile test for single lap adhesive joints has been concluded as a practical way to determine an deven to optimize steel ? FRP bondings.