Comparative Study on the Destructive and Non-destructive Evaluation of the Modulus of Elasticity of Six Hardwood Species

The modulus of elasticity (MOE) of wood is a crucial characteristic as far as its utilization is concerned. Nevertheless, the conventional approach to determine the MOE of wood is time-consuming and destructive in nature. Techniques based on vibration frequencies and the propagation of ultrasonic and stress waves are becoming increasingly popular for the non-destructive evaluation of the dynamic modulus of elasticity (DMoE) of wood. The utility of non-destructive techniques for determining the DMoE of clearwood specimens of six hardwood species, namely, Acacia spp., Ficus spp., Swietenia spp., Mangifera indica, Millingtonia hortensis, and Ailanthus excelsa, was investigated in the current study. The DMoE of wood specimens was estimated using three methods, namely, longitudinal vibration (DMoE_long), flexural vibration (DMoE_flex), and the ultrasound method (DMoE_us), and DMoE values were compared with the static modulus of elasticity determined through destructive testing in a universal testing machine. The DMoE values were found to be greater than the static MOE, and the order of increasing MOE values was as follows: static MOE followed by DMoE_flex, DMoE_long, and DMoE_us. A statistically significant correlation was observed between dynamic and static MOE. An observable strong relationship exists between density and MOE, as established by both non-destructive and destructive testing, suggesting that density significantly affects the mechanical properties of wood. The current study's findings suggest that non-destructive techniques (resonance vibrations and ultrasonic waves) have the potential to serve as a simple, reliable, and quick approach for evaluating wood stiffness.