Experimental and numerical investigation of wood fracture mechanisms at different humidity levels
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Svetlana Vasic
Abstract
Differences in fracture patterns and properties at various moisture levels are experimentally and numerically evaluated and discussed. Experiments were performed on spruce, pine, oak and beech. The influence of moisture at 98%, 80%, 65% and 30% RH and the mechanisms involved were investigated for softwoods and hardwoods subjected to opening mode I fracture using in situ and ex situ real-time environmental scanning electron microscopy (ESEM). The wedge-splitting technique was employed. To quantify the effect of humidity, fracture toughness values were obtained from ex situ tests and finite element analysis of the contact problem in wedge-splitting. In addition, lattice fracture model simulations were performed for numerical investigation of the fracture mechanisms. Distinct changes in wood fracture behaviour were observed as a function of moisture content. Fracture toughness was highest at 30% RH for all species except for oak, and showed higher values in the radial-longitudinal than in the tangential-radial direction. In green wood, water droplets moved away from the cell lumens around the crack tip. Drying of wood promotes microcracking and crack bridging as toughening mechanisms. The findings reported may be useful for further research into the interaction between moisture transfer and stress gradients in wood accompanied by moisture-crack phenomena.
©2007 by Walter de Gruyter Berlin New York
Articles in the same Issue
- Meetings
- Micromechanical modeling of solid-type and plate-type deformation patterns within softwood materials. A review and an improved approach
- Failure mechanisms in wood-based materials: A review of discrete, continuum, and hybrid finite-element representations
- Morphological lattice models for the simulation of softwood failure and fracture
- Experimental and numerical investigation of wood fracture mechanisms at different humidity levels
- Material point method simulations of transverse fracture in wood with realistic morphologies
- Simulation of cracks in wood using a coupled material model for interface elements
- Preliminary tests to evaluate the mechanical properties of young trees with small diameter
- Characterization and strength modeling of parallel-strand lumber
- Dynamic behaviour of cork and cork-filled aluminium tubes: Numerical simulation and innovative applications
- A numerical study of the transverse modulus of wood as a function of grain orientation and properties
- Effects of ring characteristics on the compressive strength and dynamic modulus of elasticity of seven softwood species
- Experimental device for the accurate determination of wood-water relations on micro-samples
- Evaluating the suitability of hybrid poplar clones for the manufacture of oriented strand boards
- Finely milled kenaf core as a natural plywood binder
- Alkaline peroxide treatment of ECF bleached softwood kraft pulps. Part 1. Characterizing the effect of alkaline peroxide treatment on carboxyl groups of fibers
- Alkaline peroxide treatment of ECF bleached softwood kraft pulps: Part 2. Effect of increased fiber charge on refining, wet-end application, and hornification
- Molar mass determination of lignins by size-exclusion chromatography: towards standardisation of the method
Articles in the same Issue
- Meetings
- Micromechanical modeling of solid-type and plate-type deformation patterns within softwood materials. A review and an improved approach
- Failure mechanisms in wood-based materials: A review of discrete, continuum, and hybrid finite-element representations
- Morphological lattice models for the simulation of softwood failure and fracture
- Experimental and numerical investigation of wood fracture mechanisms at different humidity levels
- Material point method simulations of transverse fracture in wood with realistic morphologies
- Simulation of cracks in wood using a coupled material model for interface elements
- Preliminary tests to evaluate the mechanical properties of young trees with small diameter
- Characterization and strength modeling of parallel-strand lumber
- Dynamic behaviour of cork and cork-filled aluminium tubes: Numerical simulation and innovative applications
- A numerical study of the transverse modulus of wood as a function of grain orientation and properties
- Effects of ring characteristics on the compressive strength and dynamic modulus of elasticity of seven softwood species
- Experimental device for the accurate determination of wood-water relations on micro-samples
- Evaluating the suitability of hybrid poplar clones for the manufacture of oriented strand boards
- Finely milled kenaf core as a natural plywood binder
- Alkaline peroxide treatment of ECF bleached softwood kraft pulps. Part 1. Characterizing the effect of alkaline peroxide treatment on carboxyl groups of fibers
- Alkaline peroxide treatment of ECF bleached softwood kraft pulps: Part 2. Effect of increased fiber charge on refining, wet-end application, and hornification
- Molar mass determination of lignins by size-exclusion chromatography: towards standardisation of the method
