Optimisation of cross-banded laminated veneer lumbers manufactured from blending hardwood and softwood veneers

Abstract

This paper presents a methodology to optimise the manufacturing strategy of structural cross-banded laminated veneer lumbers (LVL-C) manufactured by mixing species. The methodology is illustrated by blending nativeforest spotted gum (Corymbia citriodora) with plantation southern pine (Caribbean pine (Pinus caribaea var. hondurensis) and slash pine (Pinus elliottii var. elliottii)) veneers. The aim is to minimise the cost of a family of products (i.e. several types of product manufactured from the same veneered stock) using a maximum allowable number of hardwood veneers, and in which each product has different targeted stiffness and embedment strength. Genetic algorithm, which is widely used in the optimisation of structural products, was selected as the optimisation algorithm. The orientation of the veneers and veneer grades are considered as design variables. Results show that the developed algorithm was able to consistently converge to similar solutions for all investigated cases, demonstrating its robustness. For all cases, the "high" modulus of elasticity graded spotted gum and southern pine veneers were found to be predominant in the final products. LVL-C are found in cases with high targeted embedment strength. Finally, the obtained optimum construction strategies are validated against experimental results.