1. A 21st Century Validated Approach to ASSESSING THE EFFECTS OF UNDERWATER EXPLOSIONS (UNDEX) ON MARINE MAMMALS
Tom Fetherston, Stephen Turner, Glenn Mitchell, Emily Guzas
Naval Undersea Warfare Center Newport RI
National Military Fish & Wildlife Association Workshop
Norfolk VA
27 March 2018
LPD 19 shock trial Mesa Verde
DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited

2. INTRODUCTION
DoD operations, training, coastal construction activities expose marine mammals to man-made noise/shock
Mortality and serious injury from blast exposure have been documented in a number of species, including common dolphins and humpback whales (e.g. Danil et al 2011, Ketten et al 1993).

3. LUNG DYNAMICS Goertner Approach
Assumed lungs can be represented by a freestanding spherical gas bubble with an omni-directional shock wave
Neglects:
Presence of tissue and ribs surrounding lungs
Internal lung composition (assumed to be air)
Directional nature of most UNDEX events
Used Lovelace Foundation (sheep, dog, and monkey) data
Assumed lung structure of marine mammals similar to terrestrial animals

4. 3-YEAR PROJECT ROADMAP Computational Experimental
Match DYSMAS to Goertner
Include asymmetric shock wave
Add tissue layer(s) around lung volume
Impedance
Elasticity
Evaluate DYSMAS model against experiment
Add rib structure around lungs
Results shown for Beginning of Year 3
UNDEX against spherical gas volume surrounded by elastomer
Include representative rib cage
Include non-spherical gas volume
Experimental

5. OVERALL OBJECTIVE
Build a representative Fluid Structure Interaction (FSI) model of a marine mammal
Skeleton/rib structures
Blubber & Muscle
Realistic geometry/lung volume

6. Highlights of FY16-FY17 Modeling NSMRL “Dodgeball” Experiments at URI
Metrics available vs. experiment:
Ball shape: in air or submerged
Center point out-of-plane displacement
Pressure at sensors in water
Digital image correlation (ball rear or side face)
DYSMAS model includes tank
Reflection effects important over multiple bubble pulses
Simulated Pressure Results

7. SHAPE OF AIR-FILLED BALL NSMRL “Dodgeball” Experiments at URI
Freestanding in Air
Model
Experiment
Submerged to 33-in depth
Model
Experiment
“Teardrop” shape, due to hydrostatic depth gradient and ball buoyancy

8. MODEL RESULTS VS. VIDEO (RP80, Experiment #2)
Time: 10 ms
Video Still Frame:
Cavitation bubbles
Time: 18 ms
Video Still Frame:
Small pockets of cavitation

9. Influence of Ribs GLOBAL metric:
Minimal change in effective air bubble radius for inclusion of generic ribs
LOCAL metric:
Inclusion of ribs produces different pattern of resultant displacement in encapsulating structure
Without Ribs
With Ribs
T. Fetherston, S.E. Turner, G. Mitchell, E. Guzas, “Investigation of Marine Mammal Lung Dynamics when Exposed to Underwater Explosion Impulse,” The Anatomical Record, in press

10. INFLUENCE OF RIB STRUCTURE
Introduction of Rib Structure using Dynamic System Mechanics Analysis Simulation (DYSMAS)
T. Fetherston, S.E. Turner, G. Mitchell, E. Guzas, “Investigation of Marine Mammal Lung Dynamics when Exposed to Underwater Explosion Impulse,” The Anatomical Record, in press

11. EXTENDED RESEARCH
Utilize specimens of cetacean thoracic structure to obtain realistic material properties for inclusion in the model.
Differences in material characterization (properties, mechanical response) for fresh vs. previously-frozen tissue
Freezing tissue: how much is lost?
Validation testing and modeling with added complexity
In discussions with NSMRL about potential to conduct experiments at URI with dodgeball surrounded by rib structure
Full-scale validation testing with Kogia (dwarf sperm whale) replica built using artificial tissue
Work cooperatively with NSMRL (Brandon Casper)
Ichan School of Medicine at Mt. Sinai (Joy Reidenberg)

12. Next Level of Complexity: Realistic Material Properties
Rubber Dodgeball, Air-filled
CT Section of B’nose Dolphin
Ref: James Finneran, “Whole-lung resonance in a bottlenose dolphin (Tursiops truncatus) and white whale (Delphinapterus leucas),” JASA, 114, 529 (2003).
PIT STOP!!!
Specimen Collection
Mechanical Testing
Fit Data to Material Constitutive Models
Increase Model Complexity

13. QUESTIONS?