USACM Student Chapter Seminar Series

July 31, 2026; 1:00 PM EDT

Join via Zoom: https://us06web.zoom.us/j/82464478256?pwd=ZMkJVFdjMJzadgnVWFPqsdUSs4qTaY.1

Speaker: Enze Chen, University of Wisconsin–Madison

Physical mechanisms of blast-induced large deformations in brain-like soft matter

Abstract

Blast-induced traumatic brain injury (bTBI) is a significant burden in the military population, often termed an invisible wound from training and combat. Although postmortem pathologies have been reported in the literature, the physical mechanism underlying their origin remains unclear. Several difficulties obstruct establishing direct causation between blast loading and injurious brain deformation: the fast shock transit and transient pressure loading, the inaccessibility of intracranial strain measurement, the complexity of brain anatomy and material behavior, and the limited availability of facilities generating well-controlled, open-field-like blast exposures at head scale.

In this presentation, I will present our recent work on measuring deformation in a skull–brain phantom from blast exposure and use numerical and theoretical analyses to elucidate the underlying physical mechanism. Biofidelic phantoms embedded with a speckle pattern are subjected to well-controlled blast exposures and imaged with a dual-camera system spanning two timescales, followed by digital image correlation for full-field deformation. This combined approach enables simultaneous observation of ultra-fast events driven by the primary wave and the later-stage material deformations via the much slower shear waves. Our measurement reveals that the shock transit stage produces no measurable deformation and cavitation, with injurious strain emerging only later through rotation-driven shear. Coupled numerical and theoretical analyses explain the physical chain from blast loading to the net moment and force on the phantom, which drives skull rotation and internal shear deformation. The resulting strain and strain rate are governed by the magnitude and frequency content of the net moment from blast loading relative to the phantom's torsional mode. This framework identifies the key parameters dictating brain strain and strain rate and offers key physical insight into postmortem pathology observed in humans from bTBI.

Bio

Dr. Enze Chen is a postdoctoral researcher in the Department of Mechanical Engineering at the University of Wisconsin–Madison. He received his Ph.D. in Civil Engineering from Johns Hopkins University in 2024. His research lies at the interface of solid mechanics and biology, where he develops experimental approaches to uncover the fundamental physical mechanisms governing injury of biological systems under extreme loading. By integrating nonlinear solid mechanics, high-rate experiments, and multiphysics modeling, he investigates how energy from various exposures such as blast waves and directed energy is transmitted through brain tissue and how the resulting deformations drive neurobiological responses at the cellular level. His research also spans mechanics of brittle and soft architected materials, advancing the understanding of brittle failure, nonlinear deformation, and mechanical instabilities in these material systems, while providing mechanics-based principles for the design of tissue-engineering scaffolds. His broader goal is to establish predictive, mechanics-based frameworks for biological systems that connect external loading to mechanical deformation and resulting biological response, enabling a mechanistic understanding of injury mechanisms and mechanobiology.

August 4, 2026; 2:00 PM EDT

Speaker: Teo Lara, Massachusetts Institute of Technology

Simulating Contact-Rich Fluid-Structure Interaction Problems

Abstract

Predicting how soft bodies collide, slide, and deform while immersed in a fluid is challenging: solid mechanics, fluid dynamics, and contact must be resolved simultaneously. This talk will focus on a general simulation approach for fluid-solid interaction problems based on the fully Eulerian reference map technique. Its single unified velocity field and levelset field yield an efficient formulation that can robustly handle self- and multi-body contacts for arbitrary deformable solids immersed in a Navier-Stokes fluid. We extend this framework to include frictional contacts and solid actuation, enabling simulations of many submerged, soft, active swimmers interacting through both fluid and contact forces. The method converges to the Hertzian solution for two tangentially shearing disks, and captures contact-rich dynamics in several test cases including a block sliding down a ramp, a disk rotating in a rigid hoop, and multiple deformable bodies in a fluid settling under gravity or driven by neighboring solids, all while undergoing simultaneous self-contact and friction. Together, these results establish the reference map technique as a practical Eulerian framework for modeling contacts in deformable fluid-structure interaction problems.

Bio

Teo Lara recently completed his undergraduate studies at MIT with a BS in mathematics and physics. His research focuses on developing computational methods for fluid-structure interaction problems with applications to biological systems. Under Professor Ken Kamrin, he built Eulerian simulation techniques for resolving frictional contacts between soft bodies immersed in a fluid. With Professor Jörn Dunkel, he has been studying the feeding and swimming dynamics of jellyfish, connecting vortex structures to energetic tradeoffs in prey capture. This fall, Teo will begin his postgraduate studies at the University of Cambridge, continuing to study applied mathematics in biological contexts. 

Past Seminars

Past recordings of the Student Chapter Seminar Series can be found here.

Past Student Chapter seminar information can be found here.