Bending Performance of Plantation Teakwood and Its Mechanism Based on Radial and Tangential Directions

Abstract

Curvilinear components made from solid wood bending not only enhance the use value of wood but also add a unique aesthetic to solid wood products, in line with the concept of green and sustainable development. In this study, we focused on the influence of the direction of the wood growth rings on the bending performance of teakwood and its bending mechanism, and radial and tangential bending experiments were conducted on teakwood using the synergistic softening method of a triethanolamine compounding solution and steaming. The results showed that the radial bending coefficient of the teakwood after softening treatment was 1/9.26, 41.39% higher than that for chordwise bending, 1/15.8. Through a macroscopic analysis, the stress distribution of the teakwood during radial bending was found to be uniform, while during tangential bending, the stress was mainly borne by many longitudinal growth rings, which are prone to the bending “destabilization” phenomenon. From SEM and AFM observations, it was found that the earlywood zone and latewood zone on the outermost tensile surface of the tangential bending are longitudinal; the stress redistribution problem still exists in the bending process; and ray parenchyma are the most vulnerable part, gradually extending to the earlywood zone and causing more serious bending tearing. It can be seen that the bending performance of teakwood is not only affected by the softening process but also obviously constrained by the direction of the growth rings, which is of great significance for the optimization of hardwood bending processing technology and product design.