Applications of lignin-based foam as a load-bearing component in engineered laminates

Lignin is the second most abundant sustainable material, yet it is not used in load-bearing wooden stressed-skin panels such as the sandwich type. Thus, the literature lacks technical guides for professionals to engineer lignin-based load-bearing panels. This shortcoming hinders the promising application of the new sustainable material and product. The key objectives of this paper are to introduce lignin-based engineered laminates and devise a pertinent engineering mechanic-based model and a series-type closed-form solution, including the weak bonding stiffness in panels under transverse and in-plane loads, and thermal gradient. The paper validated the finding using independent analytical solutions and experimental measurements. It also ascertained the effect of bonding stiffness on the performance of the panels. All the results indicated satisfactory agreements. Because of the mathematical complexity of the solution, a knowledge-based toolkit was coined to bring design applications into everyday practice. The numerical results indicated that bonding stiffness must not be underestimated when engineering design code mandatory serviceability is considered. What constitutes perfectly rigid bonding is also quantified by professionals to balance the design constituents. These findings establish a strong technical foundation to not only accept the novel introduction of lignin-based panels in real-world applications but also contribute to tackling unprecedented environmental, energy, and economic challenges.