Terms for Delamination in Wood Science and Technology

In Material Science, delamination is defined as a sub critical damage to the interfaces between the plies in a laminate composite that causes a reduction in the load carrying capacity of composite (Morris 1992). The terms which describe delamination in wood and wood- based composites are numerous and often confusing for multiple reasons (the use of terms which were previously considered inappropriate, new technologies related to microscopic observation of the structure, etc). A comprehensive understanding of these terms is essential for the uses of wood products under competitive conditions of modern technology. A new classification of the delamination in wood, wood products and wood-based composites is proposed, depending on its position in the member, such as: internal delamination, near surface delamination and delamination producing multi-cracking of the member. Fracture Mechanics is an useful tool for the study of initiation of cracks and growth of delamination in wood and wood-based composites. In the context of structural health monitoring, the detection of damage induced by delamination in wood-based composites can be achieved with nondestructive ultrasonic methods and with model dependent methods implemented by finite element analysis. These methods are able to provide local and global damage information, as can be seen in Chapter 3.