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Injury Biomechanics
From helmets to seatbelts to airbags, much of what keeps us safe today was developed only after years of intense investigation into the mechanisms through which we are injured. Professor K.T. Ramesh and the Tissue Dynamics Lab (TDL) are focused on establishing a rigorous understanding of how the body reacts to a traumatic event and is subsequently injured. The group focuses on elucidating tissue dynamics and injury mechanisms from the organ level down to the cellular level. The TDL works on two fronts: the research group focuses on first ascertaining the primary mechanical behavior of human tissues and second, incorporating this knowledge into developing analytical and computer models of complex human organ systems under dynamic loads.
One major focus of the TDL is the investigation of brain tissue mechanics and traumatic brain injury (TBI), an elusive trauma that affects over 1.5 million Americans each year. To gain insight into brain tissue response to severe impacts, modified Kolsky Bar impact experiments are employed to obtain data at high strain rates on the order of 1000 s-1. Coupling strain gages, quartz crystals, lasers and laser photodiodes, the dynamic behavior of human brain tissue is measured under both compression and shear. The TDL includes a high-speed camera capable of capturing between 20,000 and 1,000,000 frames per second, so that the entire impact process can be visualized.
Once the mechanical response of the various components of the brain is understood, we construct computational models (typically using finite elements) of sub-sections of the brain and of the head as a whole. Owing to the extensive anatomy of the head and the inherent complexity of brain tissues, these computer models incorporate everything from fluid-filled ventricles to hyperelastic grey-matter lobes. The computational models are intended to simulate a range of traumas from a simple knock-on-the-head to the shockwave of an explosion (resulting, for example, from an Improvised Explosive Device). These models reproduce what happens literally in the blink of an eye, with simulations running under very high forces for mere milliseconds. These investigations of injury shed light not only onto the external conditions that cause injury, but on the microscopic phenomena that are responsible for some of the most devastating injuries sustained by humans.
