Fracture behaviour of historic oak wood

Damage that might originate from climate fluctuations can be observed on decorated oak wooden panels in historical Dutch cabinets and panel paintings. A thorough analysis of the damage mechanisms is needed to obtain a comprehensive understanding of the causes of damage and to develop sustainable conservation strategies. For this purpose, the combined experimental and numerical characterisation of the fracture behaviour of historic and new oak wood is studied. Three point-bending tests are performed, and the measured failure responses and fracture paths are compared against results computed with a finite element model, in which discrete fracture behaviour is simulated with an interface damage model. The experimental and numerical results are in good agreement. The experiments show a quasi-brittle fracture response for the oldest samples and a more brittle fracture response for the new samples. In addition, the strength required for crack initiation along a radial-longitudinal fracture plane is higher than for a tangential-longitudinal fracture plane and the strength depends on the specimen size. Photographs and scanning electron microscopy photos illustrate that fibre bridging is more apparent for the oldest samples, and that the location of crack initiation is set by geometrical imperfections. Moreover, differences in density characterize the crack propagation path