Multivariate analysis of near-infrared hyperspectral imaging for identification of moisture content in wood under static load

The relationship between wood and moisture content is complex and can lead to a range of issues, such as cracking due to dimensional changes and fungal degradation (Sargent, 2019). Wood expands in response to increased moisture content. The moisture content can be affected by the external loads that compress the wood fibres and reduce their ability to absorb moisture to some extent (Kersavage, 1973; Tsai and Ansell, 1990), while numerical calculations have shown that varying loading conditions redistribute moisture content in wood (Chen et al., 2019). The determination of moisture content under static loading conditions and varying relative humidity is important to understand the behaviour of wood in service. For this, we designed specialized fixtures to apply static loads on woodblocks in both the radial and tangential directions during conditioning. Near-infrared hyperspectral imaging and principal component analysis were used to identify the change in wood moisture content under static loading conditions.