Prediction of long term strength of adhesively bonded steel/epoxy joints in sea water

Abstract

This study is concerned with the development of a tool to predict the long term behaviour of adhesively bonded steel joints aged in sea water. First, diffusion kinetics and the mechanisms governing the degradation of mechanical properties of an epoxy adhesive are described. These two sets of data were used in a coupled finite element (FE) analysis to determine the stress state in double lap shear (DLS) specimens before and after aging. However, subsequent tests on DLS specimens indicated an adhesive and not cohesive failure mode, so this approach could not be used to predict failure in the present case without introducing an interfacial damage parameter. A second approach was therefore employed, in which modified Arcan samples were designed in order to identify directly how the failure envelope changed with aging. Tests were performed on these modified Arcan specimens under shear, tensile/shear and tensile loads before and after aging. The results from these tests have enabled a tension-shear failure envelope to be constructed, which may be used to predict failure in joints with more complex stress states. The application of a coupled diffusion-mechanical property approach is illustrated for the Arcan specimen loaded in tension, and its application to the prediction of failure behaviour after aging is discussed.

Adherence Measurements and Corrosion Resistance in Primer/Hot-Dip Galvanized Steel Systems

“…A coupled study of adherence with corrosion characterisation is of great interest though few studies are available [24,[26][27][28][29][30][31][32][33][34][35], whereas adherence measurement is a key point in both painted and bonding systems [36,37]. In addition, these studies always use the pull-off test.…”

Durability

“…This section describes the conditioning and test procedures required to examine the influence of moisture on adhesives and adhesively bonded joints. Moisture affects most adhesives, as discussed by Kinloch [6], Bowditch [7], Crocombe [8], and Bordes et al [9], for example, and a quantitative evaluation of its influence is essential if long-term durability is to be guaranteed. Unfortunately, the strong influence of specimen geometry on water uptake and the sensitivity of many test specimens to edge effects make the procedures necessary to determine useful design data quite complex.…”

On the peel behavior of polymer coating–steel system: Effect of hygrothermal aging

“…21 Thus, the failure occurred in the interface region between the steel substrate and primary adhesive. 29 This result reveals a harmful effect of the adopted aging on the coating disbondment mechanism.…”