Orthotropic viscoelastic creep in cellular scaffolds

Area of Science:

• Wood science
• Material science
• Biomechanics

Background:

• Recent Norway spruce measurements show stress-state-dependent normalized creep behavior.
• A fundamental understanding of this anisotropic response is lacking.
• The origin of anisotropy in wood creep is investigated.

Purpose of the Study:

• To determine if anisotropic creep in Norway spruce originates from the micro-structural, cellular nature of composite cell walls.
• To identify cell wall creep parameters using advanced modeling techniques.
• To assess the role of topology versus material response in directional creep.

Main Methods:

• Utilized surrogate-based inverse parameter determination.
• Applied hierarchical micro-mechanical and finite element method (FEM) models.
• Increased topological complexity from cell walls up to the growth ring scale.

Main Results:

• Simulated creep curves converged to universal proportionality factors despite microstructural disorder.
• Directional creep behavior was not solely attributable to tissue-scale topology.
• Non-linear material responses at stress concentration sites are crucial for accurate predictions.

Conclusions:

• The anisotropic creep in Norway spruce is influenced by factors beyond tissue-scale topology.
• Inclusion of non-linear material responses at stress concentration sites is necessary for realistic wood creep predictions.
• Further research into cell wall mechanics is warranted.