Effects of Shear Coupling on Shear Properties of Wood


  • Jen Y. Liu


Orthotropic elasticity, shear coupling, shear modulus, shear strength, shear test


Under pure shear loading, an off-axis element of orthotropic material such as pure wood undergoes both shear and normal deformations. The ratio of the shear strain to a normal strain is defined as the shear coupling coefficient associated with the direction of the normal strain. The effects of shear coupling on shear properties of wood as predicted by the orthotropic elasticity theory were validated using our recently developed shear test fixture. The validation also serves to demonstrate that the shear test fixture possesses the capability to introduce a state of pure shear to the critical section of a specimen as required and that orthotropic elasticity theory should be used to describe the mechanical properties of pure wood.


American Society For Testing and Materials (ASTM) 1976. Standard method of testing for shear modulus of plywood. ASTM D3044-76. American Society for Testing and Materials, Philadelphia, PA.nAmerican Society For Testing and Materials (ASTM)1978. Standard method of testing small clear specimens of timber. ASTM D143-52. American Society for Testing and Materials, Philadelphia, PA.nAmerican Society For Testing and Materials (ASTM) 1993. Test method for shear properties of composite materials by the v-notched beam method. ASTM D5379-93. American Society for Testing and Materials, Philadelphia, PA.nArcan, M., Z. Hashin, and A. Voloshin. 1978. A method to produce uniform plane stress states with applications to fiber-reinforced materials. Exp. Mech. 18(14): 141-146.nConant, N. R., and E. M. Odom. 1995. An improved Iosipescu shear test fixture. J. Composites Technol. Res. 17(1):50-55.nDaniel, I. M., and O. Ishai. 1994. Engineering mechanics of composite materials. Oxford University Press, London, United Kingdom. 395 pp.nForest Products Laboratory. 1999. Wood handbook. Gen. Tech. Rep. FPL-GTR-113. USDA Forest Serv., Forest Prod. Lab., Madison, WI. 463 pp.nIfju, P. G. 1994. The shear gauge: For reliable shear modulus measurements of composite materials. Exp. Mech 34(4):369-378.nIosipescu, N. 1967. New accurate procedure for single shear testing of metals. J. Mater. 2(3):537-566.nJones, R. M. 1975. Mechanics of composite materials. Scripta Book Co., Washington, DC. 344 pp.nLiu, J. Y., and R. J. Ross. 1998. Wood mechanical property variation with grain slope. ASCE 12th Engineering Mechanics Conference, La Jolla, CA. Pp. 1351-1354.nLiu, J. Y., D. Flach, R. J. Ross, and G. J. Lichtenberg. 1999. An improved shear test fixture using the Iosipescu specimen. ASME Mech. Cellulosic Mater. 85:139-147.nMarch, H. W., E. W. Kuenzi, and W. J. Kommers. 1942. Method of measuring the shearing moduli in wood. Rep. No. 1301. USDA Forest Serv., Forest Prod. Lab., Madison, WI.nPierron, F., E. Alloba, Y. Surrel, and A. Vautrin. 1998. Whole-field assessment of the effects of boundary conditions on the strain field on off-axis tensile testing of unidirectional composites. Composites Science Technol. 58(12):1939-1947.nPindera, M.-J., and C. T. Herakovich. 1986. Shear characterization of unidirectional composites with the offaxis tension test. Exp. Mech. 26(1):103-111.nTsai, S. W., and H. T. Hahn. 1980. Introduction to composite materials. Technomic Publishing Co., Inc., Lancaster, PA. 455 pp.nWalrath, D. E., and D. F. Adams. 1983. The Iosipescu shear test as applied to composite materials. Exp. Mech. 23(1):105-110.nYoungs, R. L. 1957. The perpendicular-to-grain mechanical properties of red oak as related to temperature, moisture content and time. Science 16(4):567-574.n






Research Contributions