Prediction of Modulus of Rupture from Modulus of Elasticity for Some Egyptian Hardwoods


  • M. L. M. Ei-Osta
  • O. A. Badran
  • A. O. K. El-Wakeel


Eucalyptus camaldulensis, Khaya senegalensis, Tamarix articulata, Casuarina spp., Jacaranda ovalifolia, Melia azedarach, stress grading, bending strength, modulus of elasticity, specific gravity


The MOE and MOR of 112 air-dry small, clear specimens (2 x 2 x 30 cm) of six species of hardwoods grown in Egypt were determined. Simple linear regression analysis revealed that MOR is highly correlated with MOE of Eucalyptus camaldulensis, Khaya senegalensis, Tamarix articulata and Casuarina spp. However, the "r" values for Jacaranda ovalifolia and Melia azedarach were not significant. In addition, covariance analysis showed that the six regressions equations have different slopes and Y-intercepts and therefore cannot be grouped. The only grouping was that between the regression lines of the first three species mentiones above.

Introducing specific gravity in the regression equation did not result in improving the correlation coefficients, except in the case of Casuarina spp. Using specific gravity alone for predicting the MOR was found to be unreliable due to the relatively low "r" values obtained for the species except in the case of Casuarina spp.


Badran, O., and M. L. EL-Osta. 1967. A study on the mechanical and physical properties of some timber tree species grown in U.A.R. Proc. 2nd Arab Horticulture Congr. Cairo, 25 March-6 April 1967.nBadran, O., S. A. E. Kandeel., and. S. A. Tawfik. 1975. Regression analysis of moduli of rupture and elasticity (MOR and MOE) relationship in some Egyptian grown hardwoods. Proc. 11th Conf. on Statistics and Computational Science. Cairo, 14-17 April 1975.nBritish Standards Institution (BSI) 1957. British Standard methods for testing small clear specimens of timber. British Standards Institution Bull. No. 373, London.nCorder, S. E. 1965. Localized deflection related to bending strength of timber. Second Symposium on the Nondestructive Testing of Wood. Wash. State Univ., Pullman, Washington. Pp. 461-473.nEl-Wakeel. A. O. K. 1978. Vibrational characterstics of some hardwoods directed towards the development of nondestructive test. Unpubl. M.Sc. thesis, Faculty of Agriculture, Alexandria University. 71 pp.nFreese, F. 1964. Linear regression methods for forest research. USDA For. Serv. Res. Pap. FPL 17. 136 pp.nHearmon, R. F. S. 1966. Theory of the vibration testing of wood. For. Prod. J, 16(8):29-40.nHilbrand, H. C., and D. G. Miller. 1966. Machine grading theory and practice. For. Prod. J. 16(11):28-34.nHoyle, R. J. 1968. Background to machine stress grading. For. Prod. J. 18(4):87-97.nJohnson, J. W. 1965. Relationships among moduli of elasticity and rupture. Second Symposium on the Nondestructive Testing of Wood. Wash. State Univ. Pullman, Washington. Pp. 419-459.nKennedy, D. E. 1969. A new look at mechanical lumber grading. For. Prod. J. 19(6):41-44.nMiller, D. G. 1963. Nondestructive testing of cross-arms for strength. Dep. For. Canada Publ. No. 1021. 18 pp.nO'Halloran, M. R., and J. Bodig. 1972. Nondestructive parameters of lodgepole pine dimension lumber. For. Prod. J. 22(2):44-51.nOrosz., I. 1968. Some nondestructive parameters for prediction of strength of structural lumber. USDA For. Serv. Res. Pap. FPL. 100. 6 pp.nPellerin, R. F. 1965. A vibrational approach to nondestructive testing of strectural lumber. For. Prod. J. 15(3):93-101.nSenft, J. F., and R. M. Della Lucia, 1975. Increased utilization of tropical hardwoods through species-independent structural grading. For. Prod. J. 29(6):22-28.nWalters, C. S., and W. L. Reiss. 1977. Predicting modulus of rupture from modulus of elasticity for small clear specimens of oak and cottonwood. For. Prod. J. 27(6):51-53.n






Research Contributions