Tapered Double Cantilever Beam Fracture Tests of Phenolic-Wood Adhesive Joints
Keywords:Tapered double cantilever beam, fracture energy, bondline thickness, grain angle, cure time, phenol-resorcinol
AbstractTapered double cantilever beam specimens were developed and used to test the effects of bondline thickness, wood anisotropy, and cure time on the fracture energy of phenolic-wood adhesive joints. Fracture, energy, G10, increases slowly with bondline thickness (in the range 160-100 microns) then jumps considerably (100-90 microns), and finally drops sharply at bondline thicknesses less than 70 microns. As the grain orientation with respect to the bonded surface (grain angle) is increased from zero degrees, G10 decreases and goes through a minimum at about 20 degrees grain angle. At larger grain angles, G10 increases. The fracture energy also increases strongly with cure time, reaching a plateau at long cure times.
Bascom, W. D., R. D. Cottington, and R. L. Jones, 1975. The fracture of epoxy and elastomer-modified epoxy polymers in bulk and as adhesives. J. Appl. Polym. Sci. 19:2542-2562.nBennett, S. J., K. L. DeVries, and M. L. Williams, 1974. Adhesive fracture mechanics. Int. J. Fracture 10:33-43.nCottrell, A. M. 1959. Theoretical aspects of fracture. Technology Press. New York.nGledhill, R. A., and A. J. Kinloch, 1974. Environmental failure of structural adhesive joints. J. Adhesion 6:315-330.nGotdon, J. E. 1976. The new science of strong materials, Penguin: New York. pp 112-120.nGriffith, A. A. 1920. The phenomena of rupture and flow in solids. Trans. Roy. Soc. London A221:163-198.nIrwin, G. R. 1958. Fracture—Encyclopedia of physics, v. 6. Springer-Verlag, Berlin. Pp. 551-562.nJohnson, J. A. 1973. Crack initiation in wood plates. Wood Sci. 6(2):151-158.nMijovic, J. S., and J. A. Koutsky, 1979. Effect of wood grain angle on fracture properties and fracture morphology of wood-epoxy joints. Wood Sci. 11(3): 164-168.nMostovoy, S. and E. J. Ripling, 1975. Flaw tolerance of a number of commercial and experimental resins. Adhesion Sci. Technol. 93:513-562 (edited by P. H. Lee, Plenum).nRipling, E. J., S. Mosrovoy, R. L. Patrick. 1964. Measuring fracture toughness of adhesive joints, Mater Res. Stand 4 pp 129-134.nRiver, B. H. 1978. Measurement of shear modulus and shear strength of adhesives. Forest Products Laboratory Communication, Madison, Wisconsin.nRuedy, T. C. 1977. The effect of grain angle orientation on the fracture toughness of wood adhesive systems. M.S. Thesis, Forestry and Forest Products, Virginia Polytechnic Institute and State University.nStrickler, M. D., and R. F. Pellerin, 1973. Rate of loading effect on tensile strength of wood parallel to the grain. For. Prod. J. 23(10):34-36.nWilliams, M. D. 1969. The continuum interpretation for fracture and adhesion. J. Appl. Polym. Sci. 13(1):29-40.n
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