**3.1. Methodology**

### *3.1.1. Software*

104 Injury and Skeletal Biomechanics

[4].

**Figure 10.** Tolerance curves for DAI and cerebral concussion [4, 29]

Tolerance of the head to skull fracture is much easier to determine than tolerance to intracranial injury. This is because of the definite relationship between force applied to the skull, and failure of cranial bone. Applied maximum force can be calculated from the equations discussed in the background section of head injury. Also from the Wayne State

Tolerance limits to specific types of head injury were from reconstructing accidents and comparing the injuries sustained with parameters calculated from the reconstructions. For example, Auer [33] reconstructed 25 fatal pedestrian accidents using various methods, including computer simulations. Head acceleration and impact duration were calculated, and from these, the upper tolerance limit (lowest level of loading above which the specific injury is always observed) and the lower tolerance limit (highest value below which the injury never occurs) for various kinds of brain injury were determined, shown in Figure 11

**Figure 11.** Upper and lower tolerance curves for ASDH, subarachnoid haematoma, and contusion [4]

Tolerance Curve [23-24], tolerance of the head to skull fracture can be determined [4].

MIMICS software used in this study allows user to process and edit 2D image data (CT, μCT, MRI, etc.) to construct 3D models with accuracy, flexibility and user-friendliness, Figure 12. Besides smoothening, FEA, wide variety of boolean functions, the powerful segmentation tools allow user to segment the medical CT/MRI images, and take measurements. The designs can be modified based on the simulation outcomes and can be exported to the FEA/CFD packages [44]. Additional steps like assigning material properties, part sections, assemblies, load, boundary conditions and analysis for head models then exported into the ABAQUS [45].

Comparison of Intracranial Pressure by Lateral and Frontal Impacts – Validation of Computational Model 107

**Figure 12.** Use of Mimics to create 3D models of human head

**Figure 14.** Blue/purple markers show the spots on at neck-head junction where boundary conditions

**Figure 13.** Four meshed skulls in ABAQUS

were applied
