**3.2. Validation**

Validation of the model with experimental data was carried out while keeping the properties and load applications same. In order to reproduce the impact conditions, ~8000kN load was applied to the frontal side of the head, same as in Nahum's experiment [42]. Figure 15 shows pulse duration was kept 2 ms to reduce the time step cycles. Also, to compare the results for skull fracture with the prior experimental data [34], 8kN-16kN loads were applied.

### *3.2.1. Simulation versus experiment*

To simulate the lateral impact, except the impact side on the head, all the other parameters were kept same, load was applied on the lateral side (left side) of the head as shown in Figure 14.

Nahum Experiment [42, 2] This simulation

Comparison of Intracranial Pressure by Lateral and Frontal Impacts – Validation of Computational Model 109

differences attributable to one or more of the following factors: the mesh fineness, reduced frame time steps, or by the material properties. An autopsy did not reveal any visible injury as a result of the Nahum experimental test and, therefore, based on this observation the

A 16kN load applied to the frontal side of the head while other parameters kept same. Analysis ran 1.1E-3 seconds due to large number of damaged volumes created after that instance. This was consistent with the Yoganandan [19] and Allsop [20] that fracture occurs because of applied force range of 8.8-17 kN. The intracranial pressure reached 200 kPa which was an indicator for brain contusion, oedema, and haematoma, but the pressure exceeded 200 kPa and reached 249 kPa, which was only slightly higher than the threshold

**Frontal**

0 0.5 1 1.5 2

**Figure 16.** Frontal pressure- time curve results for comparison with Nahum's experimental results.

adults in the age range of 30-50 and the mass of head was considered nearly ~ 4.5 kg).

results depict that the model is valid for the further analysis in injury biomechanics.

The history output of strain energy of the model also seemed to be at 2.2 J consistent with indications of skull fracture Figure 17. Also, from Newton's second law, the resultant acceleration of head can be calculated as a=16kN/4.5kg (sample of patients were of male

**Time(ms)**

A fall resulting in head acceleration of over 200 g and pulse duration of 3.5 ms or less would create conditions necessary for the production of bridging vein ASDH [4, 28]. Also, a= 355.5g is > 150g represents the HIC > 2000 which is non-survival head injury. Thus, these

brain tolerance thresholds were: compression: 234 kPa, tension: 186 kPa.

limit of brain (234kPa), see Figure 17.

**Pressure(kPa)**

**Figure 15.** Comparison of impact force- time curve between Nahum's experiment and current simulation
