Neutral Axis in Thermally Modified Timber Determined by Image-Based Approach

An alternative assessment procedure for the mechanical performance of thermally modified timber is presented. Non-defect beech wood (Fagus sylvatica L.) specimens were thermally modified at 180°C and 200°C and subjected to static three-point bending load. Based on the full-field strain data acquired during the tests, the neutral axis (NA) at a 50 % level of maximal loading force was identified and localized within the specimen height by means of image processing methods. The NA in specimens mildly thermally modified moved toward the tensile zone when compared to the control specimens, whereas the position of NA within the specimens severely thermally modified was comparable with the NA position in control specimens. The proposed procedure proved to be applicable for the assessment of the mechanical performance; however, in the present study, the NA movements caused by thermal modification were not found to be statistically significant.