Orthotropic Viscoelastic Creep in Cellular Scaffolds

TL;DR

This paper investigates the anisotropic creep behavior of cellular scaffolds, specifically Norway spruce, revealing microstructural influences and emphasizing the importance of non-linear responses for accurate predictions.

Contribution

It introduces a surrogate-based inverse parameter identification method applied to hierarchical models to understand microstructural effects on creep behavior.

Findings

Creep curves converge despite microstructural disorder

Directional creep behavior is not solely due to tissue topology

Non-linear responses are essential for realistic creep predictions

Abstract

Recent measurements of Norway spruce have revealed stress-state-dependent normalized creep behavior, highlighting a gap in our fundamental understanding. This study examines whether the anisotropic response originates from the micro-structural, cellular nature of composite cell walls with varying tracheid types. Cell wall creep parameters are identified via surrogate-based inverse parameter identification, applied to hierarchical micro-mechanical and FEM models of increasing topological complexity up to the growth ring scale. Despite microstructural disorder, simulated creep curves converge toward a universal set of proportionality factors. The results indicate that directional creep behavior cannot be attributed solely to tissue-scale topology, and that realistic predictions require the inclusion of non-linear material responses at stress concentration sites.