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BioMechanics and Materials Laboratory


Blast Wave Modeling With Rats

Overview

 A supersonic blast wave or shock blast induces an instantaneous increase in atmospheric pressure and causes what is called primary blast injury. Modeling blasts’ effects on rats may help to characterize and understand its mechanisms and so we have begun using three dimensional finite element models of a rat brains and heads to simulate controlled cortical impacts (CCI) and blast loading. Models are developed from MRI images using Avizo© and Mimics13©.

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3D Model of a Controlled Cortical Impact (CCI) Here, the impactor strikes a rat brain at a velocity of 3.5m/s and a depth of 2mm, illustrating the evolution of the Mises stress on the brain.


Main Studies


  • Build a three dimensional finite element model of a rat head and a rat brain
  • Simulate the conditions for controlled cortical impact and shock loading on the rat
  • Validate the rat brain model for controlled cortical impacts
  • Model the fluid structure interaction of the blast wave and the rat head
  • Compare the model's results with the experimental results for both CCI and blast loading

Blast Simulation

The Shock Tube is used to simulate primary blast injuries, injuries caused by the force of the initial 1-dimensional blast wave. Mechanical data is generated by the Shock Tube and is then used to help model the event. This is a model of the rat's head sitting on the rigid stand, which is located inside the middle of the Shock Tube as shown in the model.

Controlled Cortical Impact

Controlled Cortical Impact is used to analyze secondary blast injuries, the injuries caused by collision with debris displaced by the explosion. The above image is the model of the rat's head meeting the impactor.

3D Modeling

Avizo© and Mimics© are the primary tools used to generate the 3D models used in the calculations of a blast wave's effects on the rats. Here you see models of the distinct layers in the rat's head, each with its own mechanical properties to more accurately analyze the impact. The models are created using the process below:

  • Avizo is used to segment the skull, brain, and muscle layers from the raw MRI images to create 2d masks.
  • Once segmentation is done, the masks are exported in image format to Mimics where subtle corrections are made.
  • A 2d mesh is generated using Mimics.
  • Mimics or Hypermesh is then used to refine the 2d Mesh and then create a 3d finite element mesh.