Numerical modeling in timber engineering – moisture transport and quasi-brittle failure

With the rising popularity of timber structures and the increasing complexity of timber engineering projects, the need for numerical simulation tools specific to this building material is gaining rapidly in importance. in particular, moisture transport processes and the quasi-brittle failure behavior, both difficult to describe, present major challenges and are of great relevance in practical construction. For these reasons, this article presents numerical modeling concepts for predicting moisture gradients, estimating effective stiffness and strength, and numerically identifying potential cracking mechanisms in wooden components. These concepts are validated through experimental test programs, and the associated challenges are addressed. selected results ultimately demonstrate the capabilities and relevance of such methods for timber engineering

Simulating failure mechanisms in wooden boards with knots by means of a microstructure-based multisurface failure criterion

(VLID)279048

A numerical approach to describe failure of wood - From the wood cell level up to wood-based products

For the description of the failure processes in clear-wood, a multiscale approach, based on the Finite Element (FE) method, was performed. In a previous work, failure mechanisms at the single wood cell level were identified by using a unit cell approach in combination with the eXtended Finite Element Method (XFEM). Finally, a multisurface failure criterion was obtained. Within this work, these results were combined in another unit cell at the annual year ring level, where late-(LW) and earlywood (EW) cells form a layered structure. Subsequently, a single multisurface failure criterion with predefined global crack directions at the clear-wood level could be won, which will be implemented into the commercial FE software Abaqus through a subroutine. In combination with a previously developed FE simulation tool, which allows the 3D virtual reconstruction of different wood-based products, including knots and the surrounding fiber deviations, the main failure mechanisms in such products can now be captured realistically. Thus, the influences of knot configurations on several effective properties, like modulus of elasticity or bending strength, can be determined. Moreover, the resulting effective stiffness properties are used to study strengthening and load-transfer effects between lamellae in Glulam and CLT elements