Prediction of Modulus of Rupture from Modulus of Elasticity for Some Egyptian Hardwoods
Keywords: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.
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