Welcome to IMR

IMR is an advanced computational tool for Inertial Microcavitation Rheometry (IMR), enabling the characterization of soft materials under high strain-rate conditions. IMR correlates the evolution of bubble pressure and stress fields in a material with kinematic observations obtained from high-speed videography.

IMR is actively developed by researchers at multiple institutions (alphabetical):

• Spencer Bryngelson (Georgia Tech)
• Jon Estrada (University of Michigan)
• Christian Franck (University of Wisconsin-Madison)
• David Henann (Brown University)
• Eric Johnsen (University of Michigan)
• Mauro Rodriguez (Brown University) - Lead Developer
• Jin Yang (University of Texas at Austin)

For questions, contact Mauro Rodriguez or request to join the IMR Slack workspace.

Features

IMR offers several key capabilities for modeling and analyzing inertial microcavitation:

• Bubble Dynamics Simulation: Implements both finite difference and spectral methods for discretizing partial differential equations, as detailed in:
  • Estrada et al., "High Strain-rate Soft Material Characterization via Inertial Cavitation," Journal of the Mechanics and Physics of Solids, 2017.
  • Warnez and Johnsen, "Numerical modeling of bubble dynamics in viscoelastic media with relaxation," Physics of Fluids, 2015.
• High Strain-rate Characterization: Analyzes high-speed video data to extract material properties under dynamic loading.
• MATLAB Integration: Provides scripts and functions for simulation control, data analysis, and visualization.
• Experimental Validation Support: Facilitates comparison between simulation results and experimental observations.

Getting Started

Prerequisites

IMR is implemented in MATLAB and requires the following dependencies:

• MATLAB (version R2021a or newer recommended)
• Optimization Toolbox (optional but recommended for parameter fitting)
• Image Processing Toolbox (for analyzing high-speed video data)

Installation

Clone the repository and navigate to the IMR directory:

git clone https://github.com/InertialMicrocavitationRheometry/IMRv2.git
cd IMRv2

Add IMR to your MATLAB path:

addpath(genpath('IMRv2'))
savepath

Running an Example

To run a basic simulation of bubble dynamics, execute the following command in MATLAB:

run_example.m

For additional examples, see the examples/ directory.

Documentation

Comprehensive documentation, including a user guide, can be found in the docs/ folder and on the IMRv2 website.

Citation

If you use IMRv2 in your research, please cite:

@article{Estrada_2017,
  title   = {High Strain-rate Soft Material Characterization via Inertial Cavitation},
  author  = {J. B. Estrada and C. Barajas and D. L. Henann and E. Johnsen and C. Franck},
  journal = {Journal of the Mechanics and Physics of Solids},
  year    = {2017},
  volume  = {112},
  pages   = {291–317},
  doi     = {10.1016/j.jmps.2017.12.006}
}

For additional references, see the IMR Bibliography section above.

License

IMRv2 is released under the GNU General Public License v3.0.

Acknowledgments

IMRv2 development has been supported by funding from the National Science Foundation (NSF), the Department of Defense (DOD), and other research institutions.

Contact

For issues, bug reports, or feature requests, please open an issue on GitHub or contact the maintainers.