Multiscale poroelastic model: bridging the gap from cellular to macroscopic scale

Citation:

A. Rafsanjani. 2013. “Multiscale poroelastic model: bridging the gap from cellular to macroscopic scale.” ETH Zürich (20821). Thesis Type: Dr. sc. Thesis. Publisher's Version
Multiscale poroelastic model: bridging the gap from cellular to macroscopic scale

Abstract:

Many biological and engineering materials are essentially porous or cellular, a feature which provides them with a low density and high strength and toughness.  The deformation of cellular materials in response to environmental stimuli such as changes in relative humidity is of practical interest to evaluate the durability of materials in different working conditions. In this thesis, the hygro-mechanical behavior of hierarchical cellular materials is investigated using a multiscale computational framework. Attention is focused on softwoods but the proposed model is general and can be applied to other cellular materials. In wood, the interaction of the moisture and mechanical behavior is best observed in swelling. The complicated hierarchical architecture of wood introduces a strong geometric anisotropy which is reflected in the anisotropy of its mechanical and swelling behavior. A two-step computational upscaling method is utilized to devise a finite element model for the estimation of swelling behavior of softwoods. Starting from the cellular scale which represents the underlying structure of the growth ring scale, an efficient scheme is developed for the estimation of the hygro-elastic properties of periodic honeycombs as a model for the cellular structure of wood. Predicted results are found to be comparable to experimental data at both cellular scale and growth ring level. A poromechanical approach is also presented as an alternative formulation for the estimation of the effective swelling coefficients of cellular materials. The computational approach proposed in this thesis provides a predictive tool for revealing the structure-property relations of biological and engineering cellular materials and can also be used for the design of new functional cellular materials with tailorable swelling properties. 

Last updated on 10/02/2016