Phase Field Methods in Cold Regions Material Research
Researchers from CRREL’s Advanced Materials Team are characterizing and developing innovative materials to support our warfighters in the Arctic.  Effective and sustainable operations in cold climates necessitate the use of locally sourced materials for both force protection and projection on the battlefield. Leveraging indigenous materials reinforced with natural fibers allows the Army not only to protect the US and its Arctic Circle Allies, but also the Arctic environment. These reinforced materials can be applied to various applications ranging from fabrication of ballistic-resistance structures to bridges over gaps for vehicle traversal. 
Ice is a brittle, creep-prone, and temperature sensitive material that can fail in catastrophic fashion when loaded. However, ice reinforced with a secondary material such as cellulose has the potential to be a tougher, stronger, and more thermally resistant material that is easily producible in the Arctic. This research addresses the mechanisms by which cellulose nanofibrils (CNFs) enhance the mechanical and thermal response of ice. We characterize the effect of CNFs on ice properties using optical microscopy, flexural testing, and thermal cycling. These studies demonstrate the CNFs ability to delay bulk melting of ice while also increasing mechanical strength. These improvements are observed within as little as 1 % CNF reinforcement by weight. This discovery drove us to develop computational models of these composites to both describe the mechanisms by which these phenomena occur and then predict future composite performance.
	The phase field approach to capturing both material solidification via phase change and material fracture by crack propagation is leveraged in this work. Studies of material solidification involve 3D printing of ice composites and experimental deviations in differential scanning calorimetry. Material fracture, inspired by successful ice bridging, is extended into the viscoelastic behaviour of pure ice. Furthermore, leading into Representative Volume Element development of fiber reinforced ice composites. We leverage the open-source platform Dolfinx on Onyx and Carpenter using Spack to execute parallelized models leveraging the phase field approach to solidification and fracture. We present both published and ongoing work in the icy materials realm. Currently we are exploring models to account for fiber bridging, crack arrestation, and other phenomena for fiber-reinforced composites.
IMPACT
Corroborated ice material performance for Arctic construction and mobility applications.
PRESENTER
Montmayeur, Olivier
Olivier.M.Montmayeur@erdc.dren.mil
603-646-4181
USACE-ERDC-CRREL
CO-AUTHOR(S)
Asenath-Smith, Emily
emily.asenath-smith@usace.army.mil
Thompson Towell, Kiera
Kiera.L.Towell@usace.army.mil
Fernando, Payagala
Payagala.I.Fernando@usace.army.mil
CATEGORY
Comp Chemistry & Materials
SYSTEM(S) USED
Onyx, Carpenter