Dissemination of IT for the Promotion of Materials Science (DoITPoMS)

DoITPoMS Micrograph Library Full Record for Micrograph 599

Full Record for Micrograph 599

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Micrograph no
Brief description
Frozen stress photoelastic assessment of load distribution around an ellipsoid
Araldite, birefringence Link to MATTER Glossary entry for birefringence, composite material Link to MATTER Glossary entry for composite material, Eshelby, load distribution, photoelasticity Link to MATTER Glossary entry for photoelasticity, polymer Link to MATTER Glossary entry for polymer, polymer composite, reinforcement Link to MATTER Glossary entry for reinforcement, residual stress Link to MATTER Glossary entry for residual stress, shear Link to MATTER Glossary entry for shear
Composite, Polymer, Polymer composite
Araldite (TM)
Araldite CT200/HT907 'matrix' with ellipsoid CT200/HT901 'particle'
Standard codes
Araldite is a thermoset polymer, formed by the reaction of an epoxy resin with a hardener. In this case, the epoxy resin is CT200 and the hardeners are HT901 and HT909
A 'reinforcement particle' was cast, cured and machined into an ellipsoid, and the 'matrix' cast and cured around it. A load was applied at 135deg C and stresses 'frozen in' by slow cooling through Tg
Mechanical characteristics of the particle-matrix interface are of central importance for composite materials. The distribution of shear stress along the interface is critical to the load distribution and can be evaluated by this method.
Sample preparation
The model has been compressively loaded (0.16MPa) parallel to the particle axis
Cross-polarised light microscopy
Length bar
6 mm
Further information
The experiment indicates a more uniform of shear stress than that predicted by the shear lag model, suggesting that the model underestimates the magnitude of fibre loading, especially at low fibre aspect ratios. Eshelby type models, on the other hand, successfully predict the average phase stresses, but not the form of stress varying within the fibres.
Prof T W Clyne
Department of Materials Science and Metallurgy, University of Cambridge
Licence for re-use
Attribution-NonCommercial-ShareAlike 4.0 International
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