EAPSI: Modeling Mechanical Damage Response in Protein-Bound Soils

Rosa Isamar, Stanford CA

Investigators

Abstract

Extraterrestrial construction presents many interesting and new challenges. Unlike Earth, on the moon, Mars and asteroids there are very limited resources, other than soil, out of which the shelters, roads and landing pads needed for exploration can be built. As a possible candidate, a new material composed primarily of soil held together by a solution of water and proteins called Protein-bound Soils was recently developed. This material has strength similar to unreinforced concrete. However, the material?s behavior after it has been damaged has yet to be explored. This information is critical to designing a durable material that can resist extreme environments. In this project, a collaboration between damage modeling experts at Hokkaido University in Japan and protein-bound soil experts at Stanford University hopes to explore for the first time the material's damage states and computationally model its response. To date, experimental tests of mechanical properties have shown significant variability among Protein-bound Soil samples. This variability drives the creation of computational micromechanical models to gain a better understanding of the underlying mechanics that provide strength. Currently the focus is on the micromechanical properties, with emphasis on modeling periodic unit cells that capture the interactions between the particles and the protein bridges that bind them. Moving forward, mesoscale modeling is needed to understand how the material responds to damage and how its performance is affected by fatigue and environmental attacks. To achieve this, the PI and Prof. Tamon Ueda of Hokkaido University, an expert in mesoscale damage in concrete, will explore how current mesoscale damage modeling can be applied to Protein-Bound Soils. This project would represent the first venture into mesoscale modeling of this new material and promises a framework to computationally model damage in similar earthen materials. This award under the East Asia and Pacific Summer Institutes program supports summer research by a U.S. graduate student and is jointly funded by NSF and the Japan Society for the Promotion of Science.