Material point method simulations of transverse fracture in wood with realistic morphologies
Abstract A new numerical method called the material point method (MPM) is well suited for modeling problems with complex geometries and with crack propagation in arbitrary directions. In this paper, these features of MPM were used to simulate transverse fracture in solid wood. The simulations were run on the scale of growth rings. The ease with which MPM handles complex geometries was helpful for modeling realistic morphologies of earlywood and latewood. Because MPM discretizes a body into material points, it was possible to go directly from a digital image of wood to a numerical model by assigning the location and properties of material points based on the intensity or color of pixels in an image. Because the description of cracks in MPM is meshless, it can handle a variety of crack propagation and direction criteria and can simulate complex crack paths that are a consequence of the morphology of the specimen. MPM simulations were run for cracks in the radial direction, the tangential direction, and at two angles to the radial direction. The specimens were loaded by axial displacement or by wedge opening. The MPM simulations fully included contact effects during wedge loading. Finally, the potential for coupling such simulations to new experiments as a tool for characterization of wood is discussed.