Deformation and fracture of particulate epoxy in adhesive bonds

H. Chai*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

The effect of bond thickness, t, on the mode I, mode II and mode III fracture energies of two epoxy adhesives toughened by a wide range of particle size, distribution and hardness was evaluated using DCB type test specimens. A high-magnification video recording and scanning electron microscopy were used to study the damage evolution and the post-fracture morphology in the bond. The stress-strain behavior in shear was determined for a limited number of bond thicknesses using the napkin ring test specimen. Similarly to previous findings on homogeneous polymeric adhesives, GIIC and GIIIC coincided irrespective of t. Moreover, all three fracture energies converged to a single value when t was decreased to the micrometer range. New trends were found, however, when t approached the size of the reinforcement. A predominant feature of the crack propagation in this case was coalescence of voids that originated from particles ahead of the crack tip. The relief of hydrostatic stress caused by this damage is believed to be responsible for the alteration of the mode I fracture behavior as compared to homogeneous adhesives. The stiffness of the reinforcement particles played an important role in the fracture in shear.

Original languageEnglish
Pages (from-to)163-172
Number of pages10
JournalActa Metallurgica et Materialia
Volume43
Issue number1
DOIs
StatePublished - Jan 1995

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