The QUALIFY project on certifying adhesive joints for primary maritime structures was approved by INTERREG 2Seas in August 2017.

At present, there are no certification guidelines to orient the naval industry when certifying new designs using hybrid assemblies (adhesively bonded, composite to metal connections), which limits their application to secondary structures. In QUALIFY, a multi-scale testing plan will be implemented by a consortium of 11 partners, to provide reliable insights into the long-term performance of hybrid joints operating in demanding marine environments. This will ultimately enable the increased use of adhesively bonded hybrid structures in primary structures in shipbuilding, and will also generate spin-offs to other industries.

What is still needed to enable widespread adoption of hybrid assemblies in the maritime sector?

Before adopting adhesive bonding for critical applications, manufacturers in the maritime industry want to know:

  • Will this joint be reliable after twenty years of exposure to the harsh marine environment?
  • Is it strong enough and tough enough? Can we accurately model the response of an adhesive joint?
  • How can the properties of an adhesive joint be optimised? Is there an optimal thickness?
  • What types of adhesive joint designs are best to withstand specific loading and service conditions?

These are the questions defining the scope of QUALIFY. Answering them will enable qualification of hybrid bonds in primary structures for marine applications.

Project objectives

QUALIFY will remove the barriers that currently prevent the application of adhesively bonded structures in primary structures, through an innovative combination of tests and techniques:

  • Long term prediction models on the durability of the adhesive material and composite-to-metal joint configuration;
  • Coupled effects of environment and loading conditions;
  • Accelerated test methodology and innovative test set-up; real-time aging tests;
  • Reliable inspection protocol and in-situ repair device to preserve the integrity of the monitoring mechanism within the bond.

The project will pursue the following three main objectives:

  1. Evaluate the long term structural performance of the adhesively bonded hybrid joint under representative operational and environmental conditions;
  2. Develop a reliable inspection and maintenance methodology for adhesively bonded hybrid joints;
  3. Develop a procedure (Guidelines) for the qualification of adhesively bonded hybrid joints in primary structures in marine applications.


The approach proposed requires a combination of capabilities and experiences not available within the national borders of individual participants. A blend of expertise is needed, which our consortium brings together.