Dynamic Jamming in Concentrated Particle Suspensions
Abstract
The project is a systematic investigation of dynamic jamming phenomena in suspensions, focusing on fully three-dimensional (3D) systems in the non-Brownian regime at impact speeds up to a few m/s. This investigation will combine state-of-the-art experimental techniques, including high-speed imaging using video and several modalities of ultrasound. It will break new ground by probing non-invasively the transient reconfigurations associated with dynamic jamming. The overall scientific objective of the proposed research is to provide a better fundamental understanding of dynamic jamming in concentrated particle suspensions, in order to enable the design of smart materials with adaptive stress response. Specific objectives of the project are to 1. Provide detailed experimental data on 3D dynamic jamming phenomena under different modes of excitation. Currently only limited data of this type exists, primarily for normal impact. 2. Map out the state diagram for dynamic jamming. None of the models for steady-state shear thickening currently available in the literature can provide an appropriate framework, and neither can the original jamming phase diagram for frictionless particles. Our hypothesis is that shear jamming forms a good basis for such framework, but this remains to be investigated. 3. Develop suspensions with tailored frictional as well as liquid-mediated interactions to optimize dynamic jamming properties. 4. Apply dynamic jamming concepts to develop predictive capabilities for new types of ÔsmartÕ suspensions that exhibit stress adaptive properties. The project is delineated into two closely coupled efforts: A. Exploring the Properties of the Dynamically Jammed State. This first effort will investigate key aspects concerning the basic properties of the dynamically jammed state that are still unresolved, thereby addressing Specific Objectives 1&2, above. This includes the relative importance of frictional (granular) and viscous (hydrodynamic) particle interactions in controlling how this state is established during loading and central properties such as the effective mechanical moduli. It also includes how this state reverts back to the liquid-like state once the applied stress is removed. We plan to investigate dynamic jamming in response to three different types of stress application: normal impact, Couette shear, and pulling on the suspension surface. There are many indications that the dynamically jammed solid is highly anisotropic and ÔremembersÕ the loading protocol (as might be expected if shear jamming is involved). Using either mechanical excitation of probe particles or focused high-power bursts of ultrasound will make it possible to locally excite the jammed solid along specific directions and thus investigate anisotropic response. Ultrasound imaging in combination with high-speed video tracking of the suspension surface and direct, time-resolved measurement of the overall stress will provide detailed information about the dynamically jammed state and help establish the relationship between the response to normal impact, shear, and tensile loading...
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jan 07, 2019
- Source ID
- W911NF1610078
Entities
People
- Heinrich Jaeger
Organizations
- Army Contracting Command
- United States Army
- University of Chicago