Fracture of spruce and birch in the RT crack propagation direction

摘要

This paper summarises the results of an ongoing project to investigate the fracture behaviour of spruce (Picea abies) and birch (Betula spp.) wood under pure Mode I loading in the RT-direction. Specimens have been studied under "green" and air dried conditions, using small Compact Tension specimens. Combining mechanical testing with optical microscopy and image capture, local deformations of the specimen and crack propagation were computed using the Digital Image Correlation (DIC) method. Based on DIC analyses, large radial deformations were detected approximately 1 mm ahead of the macro-crack tip. Further work has focused on obtaining a more detailed understanding of the fracture phenomenon, by performing similar tests in an Environmental Scanning Electron Microscope (ESEM).