Analysis of the adhesive thickness effect on failure pressure of metal/composite hybrid joints in pressurized blister tests

Composite repairs are increasingly being used to restore the work capability of pipelines with through-wall defects by corrosion. In this context international standards, such as ISO and ASME are the references to design this kind of repair and to qualify such systems. The referred standards do not take into account the ad-hesive layer thickness (h) on the model for the calculation of the failure pressure (Pcr), as well as for the calculation of the energy release rate (gamma). In this work an experimental investigation evidences the influence of the adhesive thickness on the failure pressure. In order to achieve these results, pressurized blister tests were performed in which the geometrical parameter (h) varied from 0,5 mm to 2,0 mm. Ultimately, an empirical model to calculate Pcr as when the critical energy release rate (gamma LCL) is a function of the adhesive layer thickness was proposed.

Automated summary

Composite repairs are increasingly used for restoring the work capability of pipelines with through-wall defects caused by corrosion. International standards, such as ISO and ASME, are used for designing and qualifying such repairs. However, these standards do not consider the influence of adhesive layer thickness on failure pressure and energy release rate. This paper presents an experimental investigation that demonstrates the impact of adhesive thickness on failure pressure and proposes an empirical model to calculate failure pressure as a function of adhesive layer thickness.