Computational Modeling and Simulation of Viscoelastic Granular Packings

In the domain of granular materials, understanding the mechanical properties of soft, viscoelastic systems is paramount due to their widespread relevance in both industrial and natural environments. A comprehensive understanding of their compaction behavior is essential for optimizing processes and designing efficient systems. This thesis investigates rate-dependent mechanics of two dimensional (2D) viscoelastic granular packings, aiming to unravel the complex relationship between particle-level properties and macroscopic responses. We perform a suite of finite element simulations under rate-dependent uniaxial compaction. The study commences with an analysis of a granular lattice featuring particles arranged in a square packing, revealing two distinct regimes in force-displacement behavior influenced by loading time-scale and rate-dependent porosity evolution. This investigation extends to polydisperse packings, examining the impact of initial porosity. Analytical models are formulated to predict force-displacement and porosity evolution, enhancing our comprehension of compaction processes. A particle packing algorithm is introduced to generate assemblies compatible to Finite element analysis (FEA) environment, offering the capability to use different particle size distributions (PSDs) and equipped with post-processing options. The thesis also presents systematic study of local statistics of large assemblies for different PSDs by using the aforementioned post-processing options. A concept of microstructurally equivalent statistical volume elements (ME-SVEs) is introduced to capture characteristics of the large parent assembly efficiently. A specific focus is given to interface strength in deformable granular systems, particularly in the context of vitrimers compaction. An analytical model is developed to investigate the evolution of chain density at the interface between different networks, resulting in a transient advection-diffusion-reaction (ADR) equation. The influence of temperature and association-dissociation rates on interface welding has also been presented. Overall, the findings in this thesis expand our understanding of 2D viscoelastic granular systems, offering insights for process optimization and designing materials with tailored mechanical properties.

Name thesis:degree_name

Doctor of Philosophy

Discipline thesis:degree_discipline

Mechanical Engineering

Grantor

University of Houston

Year dc:date.issued

2025

Author dc:creator

• Selvaraju, Srinivas

Advisor dc:contributor.advisor

• Joshi, Shailendra P

Committee members dc:contributor.committeemember

• Nakshatrala, Kalyana B.
• Kulkarni, Yashashree
• Chen, Tian
• Baxevanis, Theocharis
• Ferdowsi, Behrooz

• Mechanical engineering
• Engineering

Language dc:language.iso

English

Handle dc:identifier.uri

https://hdl.handle.net/10657/19468

OAI identifier oai:identifier

oai:uh-ir.tdl.org:10657/19468