Characterisation and modelling of the rate-dependent behaviour of adhesive bonded interfaces

Thesis

This thesis develops a numerical and experimental framework to model and characterise the rate-dependent mechanical performance of adhesively bonded structures. Experimental methods suitable for various strain rates – including impact – enable direct measurement of mechanical properties to derive accurate adhesive interface models – such as the cohesive zone modelling approach. First, this thesis explores a newly developed experimental method. This was developed to enable the characterisation of adhesive joints for different loading rates. The method is then used to characterise the rate, fracture mode and thickness dependent behaviour of ductile adhesive inter- faces. Microstructural analysis is performed to prove the validity of the experimental measurements to calibrate cohesive zone models. These results are also used to rank two different types of adhesives: paste and film adhesive. Second, the experimental results are used to develop a cohesive zone model that captures all critical aspects of the observed phenomena. Third, fracture mechanics experiments are performed to understand the rate-dependent behaviour of similar and dissimilar material combinations. A new data acquisition method is developed for the high-rate mechanical response of the adhesive interface which relies entirely upon digital image correlation. Moreover, experiments with dissimilar material combinations provide information about the failure sequence which depends upon the loading rate regime. To the author best knowledge this is the first time that dynamic fracture mechanics experiments are performed in hybrid material adhesive structures. Finally, simulations of the experiments for both material combinations are used to validate the newly developed cohesive zone model. The ability of the model to predict cohesive failure under a wide range of strain rates and fracture modes is demonstrated. The simulations are then used to rationalise the failure performance of hybrid material adhesive joints.

Authors: Lissner, M

• DOI: 10.5287/ora-a4a966ezd
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English