The Influence of Overlap Length on Adhesive Joint Strength


  • Audrey G. Zink
  • Robert W. Davidson
  • Robert B. Hanna


Double lap joints, joint strength, adhesive connections, failure mode


The influence of overlap length on the strength and failure mode of bonded wood double lap joints was investigated in this study. The overlap lengths ranged from 12.7 mm (0.5 in.) to 44.45 mm (1.75 in.) in 6.35-mm (1/4-in.) increments. The side members were 50.8 mm (2 in.) long, and the center member was 88.9 mm (3.5 in.) long. All joint members were 25.4 mm x 25.4 mm (1 in. x 1 in.) in cross section. The type of wood was yellow-poplar (Liriodendron tulipifera), and the joints were loaded in double shear. The strength of the joint was found to increase slightly with increased overlap length. The failure mode of the joints shifted from cleavage of the side members for the shortest overlap lengths, to a combination of side splits and forward shear failures for the intermediate overlaps, to center splits for the longest overlap lengths studied. While the joint strength trends observed for the double lap wood joints were consistent with previous work on other materials and similar conditions, the failure modes with the wood adherends were different from any other studies to date.


Adams, R. D. 1989. Strength predictions for lap joints, especially with composite adherends. A review. J. Adhesion 30:219-242.nAdams, R. D., R. W. Atkins, J. A. Harris, and A. J. Kinloch. 1986. Stress analysis and failure properties of carbon-fibre-reinforced-plastic/steel double lap joints. J. Adhesion 20:29-53.nAdams, R. D., and V. Mallick. 1993. The effect of temperature on the strength of adhesively-bonded composite-aluminum joints. J. Adhesion 43:17-33.nAmerican Society for Testing and Materials (ASTM). 1986a. Standard test methods for strength properties of adhesive bonds in shear by compression bonding. Standard D-905-49. American Society for Testing and Materials, Philadelphia, PA.nAmerican Society for Testing and Materials (ASTM). 1986b. Method A, Ovendry Method. Standard D-2016-83. American Society for Testing and Materials. Philadelphia, PA.nAmerican Society for Testing and Materials (ASTM). 1986c. Method D, Volume by Mercury Immersion. Standard D-2395-83. American Society for Testing and Materials. Philadelphia, PA.nBodig, J., and B. A. Jayne. 1982. Mechanics of wood and wood composites. Van Nostrand Reinhold Company, New York, NY.nBullen, I. C. 1986. The design and construction of glued joints. J. Inst. Wood Sci. 10:220-228.nChen, D., and S. Cheng. 1983. An analysis of adhesive-bonded single-lap joints. J. Appl. Mech. Trans. ASME (March 1983) 50:109-115.nCornell, R. W. 1953. Determination of stresses in cemented lap joints. J. Appl. Mech. Trans. ASME (Sept. 1953) 75:355-364.nDe Bruyne, N. A. 1967. The measurement of the strength in adhesive and cohesive joints. In R. Houwink and G. Salomon, eds. Adhesion and adhesives, vol 2. Elsevier Publishing Company, New York, NY.nDe Bruyne, N. A., and R. Houwink. 1951. Adhesion and adhesives. Elsevier Publishing Company, New York, NY.nDelale, F., and F. Erdogan. 1981. Viscoelastic analysis of adhesively bonded joints. J. Appl. Mech. Trans. ASME (June 1981) 48:331-338.nGilibert, Y., M. L. L. Klein, and A. Rigolot. 1988. Mechanical behavior assessment of epoxy adhesive in the double-lap joint. Pages 39-53 in W. S. Johnson, ed. Adhesively bonded joints: Testing, analysis, and design. ASTM STP 981. American Society for Testing and Materials, Philadelphia, PA.nGlos, P., D. Henrici, and H. Horstmann. 1988. Shear strength of glued lap joints in timber structures. Pages 663-672 in 1988 International Conference on Timber Engineering, September 19-22, Seattle, WA.nGoland, M., and E. Reissner. 1944. The stresses in cemented joints. J. Appl. Mech. Trans. ASME (March 1944) 66:A17-A27.nGoodman, J. R. 1969. Layered wood system with interlayer slip. Wood Sci. 1(3): 148-158.nHart-Smith, L. J. 1987. Adhesive-bonded single lap joints. NASA Report CR-112236, Langley Research Center, VA.nHilbrand, H. C. 1964. Comparison of block shear methods for determining shearing strength of solid wood. Res. Note FPL-030, USDA Forest Serv., Forest Prod. Lab., Madison, WI.nHoyle, R. J., Jr. 1988. Design of wood shear joints fastened with nails and structural elastomeric adhesive. Pages 38-45 in 1988 International Conference on Timber Engineering, September 19-22, Seattle, WA.nKinloch, A. J., and R. J. Young. 1983. Fracture behavior of polymers. Appl. Sci. Pub., London, UK.nKrueger, G. P. 1981. Design methodology for adhesives based on safety and durability. Pages 321-351 in Adhesive bonding of wood and other structural materials. EMMSE Project. Materials Research Lab. Pennsylvania State University, University Park, PA.nLunsford, L. R. 1961. Design of bonded joints. Pages 9-13 in Symposium on Adhesives for Structural Applications, September 27-28, Dover, NJ.nMallick, V., and R. D. Adams. 1987. The stresses and strains in bonded joints between metal and composite materials. Pages 10.1-10.7 in Adhesion '87. Plastics and Rubber Institute, London, UK.nMallick, V., and R. D. Adams. 1989. Strength prediction of lap joints with elasto-plastic adhesive using linear closed form methods. Pages 160-165 in Proc. Structural Adhesives in Engineering. Butterworths, London, UK.nMcLaren, A. S., and I. MacInnes. 1957. The influence on the stress distribution in an adhesive lap joint of bending of the adhering sheets. Br. J. Appl. Phys. 9:72.nMcLeod, A. M., L. A. Yolton, W. A. Sanborn, and R. S. Phillips. 1962. A comparison of shearing strengths of glued joints at various grain directions as determined by four methods of test. FPL Rep 1522. USDA Forest Serv., Forest Prod. Lab., Madison, WI.nMylonas, C., and N. A. De Bruyne. 1951. Static problems, Pages 91-143 in N. A. deBruyne and R. Houwink, eds. Adhesion and adhesives. Elsevier Publishing Company, New York, NY.nNorris, C. B. 1957. Comparison of standard block-shear test with the panel-shear test. Forest Prod. J. 7(9):299-301.nOkkonen, E. A., and B. H. River. 1988. Factors affecting the strength of block-shear specimens. Forest Prod. J. 39(1):43-50.nPanshin, A. J., and C. De Zeeuw. 1980. Textbook of wood technology, 4th ed. McGraw-Hill Book Company, New York, NY.nPatton-Mallory, M., and S. M. Cramer. 1987. Fracture mechanics: A tool for predicting wood component strength. Forest Prod. J. 37(7/8):39-47.nRenton, W. J., and J. R. Vinson. 1975. The efficient design of adhesive bonded joints. J. Adhesion 7:175-193.nRiver, B. H., and R. H. Gillespie. 1978. Measurement of shear modulus and shear strength of adhesives. FPL Research Report, USDA Forest Prod. Lab., Madison, WI.nSancaktar, E. 1991. A comparison of linear with nonlinear viscoelastic solutions for shear stress concentration in double lap joints. J. Adhesion 34:211-220.nSelbo, M. L. 1975. Adhesive bonding of wood. Tech. Bulletin No. 1512, USDA Forest Serv., Washington, DC.nSuddarth, S. K. 1961. The design of glued joints for wood trusses and frames. Res. Bull. No. 727, Wood Research Lab., Purdue University, Lafayette, IN.nUSDA. 1974. Wood handbook: Wood as an engineering material. US Forest Products Lab, Agric. Handbook No. 72, Supt. Documents, U.S. Govt. Printing Office, Washington, DC.nVolkerson, O. 1938. Die nietkraft verteilung in zugbenspruchten nietverbindugen mit constanten laschenquerschnitten. Luftfahrtforschung 15:41-47.nWilliams, J. G., and M. W. Birch. 1976. Mixed mode fracture in anisotropic media. Cracks and Fracture. ASTM STP 601. American Society for Testing and Materials. Philadelphia, PA. Pp. 125-137.nZink, A. G., P. J. Pellicane, and C. E. Shuler. 1994. Ultrastructural analysis of softwood fracture surfaces. Wood Sci. Technol. 28:329-338.n






Research Contributions