Adhesive Bonding of Composite Joints PhD Project Ian Campbell RP/Composites Facility University of the Witwatersrand

Slide 2 © CSIR Why Adhesive Bonding? Proliferation of composite structural equipment in many fields Advantages Speed of manufacture Uniform stresses High strength Repair patches

Slide 3 © CSIR Problems Environmental effects Moisture diffusion and absorption Thermal changes Adhesive property changes Stress analysis Fatigue Creep

Slide 4 © CSIR Typical Bond Configuration Scarf Joint Single Lap Joint adhesiveload Composite adherend

Slide 5 © CSIR Factors Affecting Bond Strength Surface preparation and cohesion Bond thickness Composite adherend layup Adherend material properties Residual stresses

Slide 6 © CSIR Modelling Methods Analytical Finite Element Methods Rayleigh-Ritz Method

Slide 7 © CSIR Finite Element Methods Elastic model Non-linear elements – Elastic-plastic Spring elements

Slide 8 © CSIR Experimental Methods Strain gauges Photo-elasticity Surface coating crack analysis Microscopy

Slide 9 © CSIR Typical Specimen Strain gauges

Slide 10 © CSIR Comparison Strain distribution at 780 N 0.00E E E E E E E E E Location Strain Spring model Experiment Elastic –plastic model

Slide 11 © CSIR Photoelasticity -Reflective film attached to sample -Limited resolution

Slide 12 © CSIR Proposed Solutions Microscopy for strain measurement Rayleigh-Ritz modelling methods