Figure 1: Overview of activities carried out in the Dynamic Failure of Materials group: a) cross sections of monolithic and sandwich composite panels subjected to underwater impulsive loading, b) composite sandwich panel subjected to underwater impulsive loading, c) Fluid-Structure Interaction experimental setup in the lab with laser illumination for shadow Moiré, d) dynamic fragmentation simulation of a ceramic, e) dynamic shear band failure surface on a martensitic high strength steel tested in torsion

Dynamic events differ significantly from quasi-static ones and occur ubiquitously in the real world of space, mass and time (vehicle crash, foreign object impact, blast produced by explosions). Our research approach employs both experimentation and modeling to obtain in-depth knowledge of failure mechanisms, including high strain rate deformation, dynamic crack propagation, delamination, fragmentation and dynamic buckling. The group's interests have spanned a broad range of materials such as composites, ceramics, metallic foams, and sandwich structures (Figure 1).

Each investigation is carried out with state-of-the-art experimental equipment consisting of a 3-inch light gas gun, a 1-inch Kolsky bar, and miniature loading stages. We combine a variety of measurement methodologies from novel optical set-ups comprising several laser interferometric techniques. A Cordin 8-CCD high-speed camera and full-field Digital Image Correlation (DIC) are used as diagnostic tools. The high-speed camera is also used to record the deformation history of structures by means of shadow Moiré. Post mortem analysis of the samples is carried out with state-of-the-art experimental equipment including Atomic Force Microscope (AFM), Scanning Electron Microscope (SEM), laser profilometer, and phase-shift white-light interferometer. The group also developed computational models to capture the mechanics of dynamic cracking and delamination as well as mesoscale grain level modeling using cohesive interface element.

Projects: 

1. Fluid Structure Interaction
2. Fiber Composite Panels
3. Instabilities in Novel Alloys
4. Dynamic Failure Modeling