Wood

Wood is the hard tissue of trees and shrubs. In addition to lignin, it also contains the skeleton substances cellulose and hemicellulose as well as extractives and minerals. A distinction is made between the individual tissue areas of a tree - heartwood, sapwood, bast and bark.

The wood's Material properties - such as porosity, anisotropy and hygroscopicity - are determined by its natural, organic origin. Heartwood and sapwood also have different permeabilities and durabilities.

As a material, wood tends to absorb moisture from the environment. Variable ambient Humidity therefore results in poor dimensional stability and also causes fluctuations in shape due to swelling and shrinkage. Using technology to modify wood can limit its hygroscopicity.

Wood is one of the viscoelastic materials for which load duration, the type of Force acting (static, dynamic) and the direction in which the load is applied need to be taken into account.

As a biodegradable material, wood needs to be protected to stop it being destroyed by biological pests (especially insects and fungi). Appropriate measures include chemical preservation and the use of resistant heartwoods and modified (thermotreated, acetylated) wood.