Analysis of Radiographic Contrast Markers for X-ray Digital Image Correlation of Tissue-Simulants Under Dynamic Load

The study of traumatic brain injury is critical to the improvement of protective equipment. Numerical models of brain deformation require real-world data for validation. In preparation for upcoming cadaver studies, a novel method of measuring displacement and strain fields of optically inaccessible internal planes using high-speed X-ray, embedded contrast markers and digital image correlation (DIC) is presented herein. An uncoupled scintillator and optimally-selected high-speed camera enable continuous X-ray imaging through a human head at 10,000 fps. As varying composition creates radiographic contrast, contrast within a human brain is limited, therefore, artificial contrast markers are required. Markers must be dynamically coupled to the bulk material and provide sufficient X-ray contrast. An analytical tool was developed to design of contrast markers. The impact of contrast-to-noise ratio and out-of-plane motion on DIC accuracy were quantified. Finally, a feasibility study using a biofidelic headform subjected to a NOCSAE drop test is presented.