Report 14 - Overall Summary

Key messages arising from Project No 3 are listed in this report.

Test Methods

• Simple tests are not discriminating enough.
• It is vital in ranking systems consistently.
• For non-stress specimens the tensile butt joint is more suitable than the lap joint.

Moisture Absorption

• Use of sensor techniques to monitor in-situ the level of water uptake is preferred.

Forensic/Analytical Studies

• Accelerated ageing tests are unrealistic in terms of quantitative prediction of joint service life.
• Joint performances appear to be tolerant to flaws.
• Corrosion protection of adherends is important.
• Surface preparation is vital.
• Seeking expert advice pays dividends.

Failure Mechanism

• Cohesive, or failure near the interface is common.
• Water ingression is higher than predicted by simple diffusion.
• The reduction in elastic property as a result of water swelling can be marked by altering the stress distributions.

Design Methodology

• Pragmatic approaches are effective.
• A holistic model that links water ingress, surface and adhesive effects, and joint failure is required.
• Use of fracture mechanics is effective.

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