Numerical simulations of the cathodic delamination of adhesive bonded rubber/steel joints

Cathodic delamination of mechanically loaded rubber/steel adhesive bonds occurs due to bondline degradation (weakening) followed by crack growth under mechanical (here, mostly cleavage) load. In this paper, a mechano-chemical failure criterion is proposed, which couples fracture mechanics principles with the weakening mode of debonding due to environmental effects. The latter is mainly described by electrolyte type, cathodic potential, and temperature and may be analytically described according to the recently introduced [1] analytical model based on liquid-solid reactions and is capable of simulating the weakening mode of bond degradation. This paper extends the model advanced in [1] to where we now account for externally applied mechanical loading (mostly peel mode). Such loads cause already weakened bonds to delaminate thus resulting in physical separation of the rubber from the steel substrate.For the rubber/metal, variable-G, strip blister specimen (SBS) used in this work, progressive delamination proceeds as the applied strain energy release rate, G, decreases from an initial maximum value, GT0 (of about 2.24 kJ/m2 for the most utilized specimen configuration). As the applied G decreases, delamination correspondingly proceeds at progressively slower rates. The fact that delamination rates decrease with increasing delaminated bond lengths has already been established experimentally and simulated using empirical [2] and semi-empirical models [3] but will be simulated numerically in this paper. The model is validated using such experimental data of bond delamination under a variety of cathodic conditions. The validated methodology provides numerical simulations of joint delamination of the SBS under the combined action of mechanical peel loads and cathodic environment.