Numerical Modeling of 'Green' Wood Chips Processed Through Rotary Shear

摘要

The Forest Concepts Crumbier~R rotary shear comminution machine processes "green" venee wood chips through intermeshed rotary cutters so they are "crumbled" into small particles. As the thicknes: the cutters gets smaller, understanding the processingforces is important for optimizing the design . appropriately strong cutters. We have modeled the process using the material point method (MPM). In brief, ' process involves massive amounts of contact between the wood and the tools (cutters and spacers),la deformation/rotation of the wood material and material failure. These mechanical characteristics suggest I MPM, which has advantages for discretizing the geometry and modeling contact and material behavior, r provide numerical tools that could not bedone by other methods. We monitored contact forces and energy dui the shearing process and visualized the process in 3D.Numerical results highlight the effects of wood material strength and hardening, wood/tool friction parame and geometry (thickness and width) of the wood and cutters on the tools contact forces. Contact forces increi with the increase of material strength and plastic hardening, the cutters width and the wood sheet thickne Processing green wood results in contact forces that are 50% lower than dry wood. Contact force curves sh significant peaks corresponding to contact of wood with teeth on the cutters.MPM is a particle-based numerical analysis tool that can run virtual experiments to help optimize equipment wood comminution. The MPM analysis method may be more accurate than finite element mesh modeling biomass materials.