Comparative Studies of the Shear Strength Property of Two Members of the Fabaceae Family with Respect to Their Fibres

Aim: The shear strength of wood is a very significant parameter required in describing the potential of woods in making wooden structure. This study is aimed at comparing the shear strength of Pentaclethra macrophylla and Erythrophleum suaveolens with respect to their fibre. This is to determine the suitability of including Erythrophleum suaveolens in making traditional motars in order to reduce the demand load on Pentaclethra macrophylla.

Methods: The heartwood samples of Pentaclethra macrophylla and Erythrophleum suaveolens for maceration were fixed in specimen bottles containing formalin-acetic-alcohol (FAA) in the ratio 90:5:5 to prevent fungal growth. The preparations involved cutting small clear samples of the heartwood of the two timber species of fabaceae family. The shear strength parallel to the grain test was conducted using a Hounsfield Tensometer.

Results: Significant differences were recorded across the fibre characteristics of the two plant species. The share strength of the 25 wood samples from the two plants each fluctuate around 100 to 200 N/mm2. On the average, P. macrophylla recorded higher shear strength as compared to

suaveolens however no significant difference was recorded between the means when tested for significant differences using independent sample t-test.

Conclusion: Since the shear strength of E. suaveolens is comparable to that of P. macrophylla, it is therefore recommended its substitute for the manufacturing of wood based products where P. macrophylla has been in continual usage in order to relieve the pressure and demand on P. macrophylla.