Determination of Elastic Constants of Cross-Laminated Bamboo (CLB) through Non-Destructive Testing

Abstract

The aim of this work is the evaluation by non-destructive impulse excitation tests, the modulus of elasticity (E) and the transversal deformation modulus (G) of cross laminated bamboo (CLB). Tests were performed on twenty-three CLB specimens measuring: 12 mm (height), 40 mm (width) and 12 mm (length). Twelve specimens have two lamellas with fibers at 0 °, longitudinal direction, and one layer with fibers at 90 °, normal direction (N) and the other eleven specimens have two layers in the normal direction and one in the longitudinal direction (L). The tests were performed using the Sonelastic apparatus indicated for the estimation of the dynamic modulus of elasticity and the damping of materials by the impulse excitation technique. A software attached to the apparatus analyzes the acoustic wave generated, and from it, the dynamic modulus of elasticity is determined. In order to verify the significance of this estimation, semi-destructive, three-point bending tests were performed in a universal test machine, determining E and G. It was concluded that the estimation of the modulus of elasticity is very significant when compared with the semi-destructive tests, and this method can be used to estimate the elasticity modulus of the CLB with high precision (R2 = 99% and p-value <0.001). Modulus of elasticity in the longitudinal direction were five times larger than those in the normal direction.