Development of a finite element human head model partially validated with thirty five experimental cases.

TLDR: Studies from 35 loading cases demonstrated that the FE head model could predict head responses which were comparable to experimental measurements in terms of pattern, peak values, or time histories.

Abstract: This study is aimed to develop a next-generation, high quality, extensively validated finite element (FE) human head model for enhanced head injury prediction and prevention. The geometry of the model was based on CT and MRI scans of an adult male. A new feature-based multi-block technique was adopted to develop hexahedral brain meshes including the cerebrum, cerebellum, brainstem, corpus callosum, ventricles, and thalamus. Conventional meshing methods were used to create the bridging veins, cerebrospinal fluid (CSF), skull, facial bones, flesh, skin, and membranes - including falx, tentorium, pia, arachnoid, and dura. The head model has 270,552 elements in total. A total of 49 loading cases were selected from a range of experimental and real world head impacts to check the robustness of the model predictions based on responses including the brain pressure, relative skull-brain motion, intracranial strain, skull response, facial response, and bridging vein elongation. The brain pressure was validated against intracranial pressure data reported by Nahum et al. (1977) and Trosseille et al. (1992). The brain motion was validated against brain displacements under sagittal, coronal, and horizontal blunt impacts performed by Hardy et al. (2001, 2007). The facial bone responses were validated under nasal impact (Nyquist et al., 1986), zygoma and maxilla impact (Allsop et al., 1988). The skull bones were validated under frontal angled impact, vertical impact, and occipital impact (Yoganandan et al., 1995) and frontal horizontal impact (Hodgson et al., 1970). The FE head model was further used to study injury mechanisms and tolerances for brain contusion (Nahum et al., 1976), bridging vein rupture (Depreitere et al., 2006), and brain strains for real-world brain injury cases (Franklyn et al. 2005). Studies from 49 loading cases demonstrated that the FE head model had good biofidelity in predicting head responses under various impact scenarios. Furthermore, tissue-level injury tolerances were proposed. A maximum principal strain of 0.42% was adopted for skull cortical layer fracture and maximum principal stress of 20 MPa was used for skull diploe layer fracture. Additionally, a plastic strain threshold of 1.2% was used for facial bone fracture. Average of 17% of engineering tensile strain indicates bridging vein rupture. For brain contusion, 277 kPa of brain pressure was calculated from reconstruction of one contusion case. Lastly, the high strains predicted by the FE head model match the trend of brain injuries reported in four real-world cases. Language: en