Failure mechanisms in wood-based materials: A review of discrete, continuum, and hybrid finite-element representations

Abstract

Challenges arise in finite element (FE) analyses that predict mechanical failure in wood-based materials because their structural complexity is difficult to mimic. When considered at the macro scale, wood and engineered wood composites can reasonably be assumed to behave as homogenous continua. However, accurate meso- and micro-scale representations require a different approach. Models employing discrete FEs are robust tools for detailed failure analysis, because the elements can be made to mimic the functions of morphological structures in the material. Hybrid models that meld continuum and discrete FEs also show good promise as generalised analysis tools, but as yet their development is in its infancy. In the future, beyond mechanical damage, other energy sinks also need to be included in models, and computational efficiency should be improved. In this overview, the advantages and limitations of alternative FE representations are demonstrated in terms of failure processes in wood-based materials via case analyses.

Influence of the moisture content on the fracture characteristics of welded wood joint. Part 1: Mode I fracture

“…Finite element modeling (FEM) should be used to construct a model based on cohesive elements. FEM is a powerful tool to model the failure and interface fracture mechanisms in wood-based materials (Smith et al 2007;Landis and Navi 2009). The parameters of the cohesive law will be experimentally established with the help of DCB and uniaxial tensile tests.…”

Impact of knots on the fracture propagating along grain in timber beams

“…Smith, Snow, Asiz and Vasic 2007). Variation in material properties of timber can be reduced by strength grading the raw material as it is commonly done for e.g.…”

Determination of cohesive laws in wood bonded joints under mode I loading using the DCB test

“…In this context, a better description of the mechanical behaviour of the bonded joints is needed to improve further the efficiency and safety of wood-based structures. The modeling of crack propagation in wood and wood composites is a powerful tool (Keunecke et al 2007;Smith et al 2007;Landis and Navi 2009;Stanzl-Tschegg and Navi 2009), and this research area is in permanent development. Cohesive zone models (CZM) appear to be suitable to deal with challenges posed by the design of bonded joints (Yang et al 1999;Gonçalves et al 2003;Andersson and Biel 2006).…”