1 3 Med Biol Eng Comput DOI 10.1007/s11517-015-1295-6 ORIGINAL ARTICLE Influence of head mass on temporo-parietal skull impact using finite element modeling Debasis Sahoo 1 · Caroline Deck 1 · Narayan Yoganandan 2 · Rémy Willinger 1 Received: 27 January 2014 / Accepted: 1 April 2015 © International Federation for Medical and Biological Engineering 2015 1 Introduction The biomechanical response of human head in pedestrian accidents and side-impact motor vehicle crashes leads to temporo-parietal skull fractures in some of the cases [17, 28, 34]. Due to the proximity of interior components of vehicle, the temporo-parietal region of human head often involves in contact during lateral motor vehicle impact [7]. Around 95 % of all diffuse axonal injury (DAI) cases are associated with head contact to the interior surface of the vehicle [29]. Limited studies are reported in the litera- ture in the context of trauma biomechanics of lateral head impact [1, 7, 18, 28, 29]. In contrast to lateral region of head, the frontal impact has been investigated more often, and current regulatory injury criteria adopted worldwide were derived from the integration of the resultant linear acceleration at the center of gravity of head [15]. How- ever, injury criteria derived for frontal impacts may exceed its limits during side impacts, mostly occurred in vehicle crashes [28]. Hence, the applicability of these criteria to temporo-parietal impacts is not promising during side- impact motor vehicle crashes [7]. In-depth study in this field can provide better understanding of skull fracture mechanism and emphasis on the tolerance of the skull to lateral impact. Quantification of biomechanical tolerance is essential to describe the aspect of head injury in different accident scenarios. There are two widely adapted methods available in the literatures to enumerate the tolerance limit: One is controlled laboratory experiments [33], and the other is numerical computation using mathematical analogue [4–6]. Both the methods have their limitations. There are restric- tions and ethical issues to conduct experiments with post- mortem human surrogate (PMHS) specimen. On the other hand, mathematical simulations have the unique ability to Abstract The effect of head mass on its biomechanical response during lateral impact to the head is investigated in this computational study. The mass of the head of a state- of-the-art validated finite element head model is altered by ±10 % from the base value of 4.7 kg. Numerical simula- tions of lateral head impacts for 30 cases (representing 15 human cadaver experiments × 2 mass configurations) are performed using the LS-DYNA solver at different veloci- ties ranging from 2.4 to 6.5 m/s and three impacting con- ditions representing different stiffness and shapes of the contact/impact surfaces. Results are compared with the original model using the baseline head mass, thus resulting in a total of 45 simulations. Present findings show that the head mass has greater influence for peak interaction forces and the force has a greater dependency on stiffness of con- tact surface than the shape. Mass variations have also influ- ence on skull strain energy. Regardless of increase/decrease in skull strain energy influenced by head mass variations used in the computational study, the 50 % fracture toler- ance limit was unaltered, which was 544 mJ. The present study gives a better understanding of the mechanism of temporo-parietal skull impact. Keywords Parametric study · Temporo-parietal impact experiments · Peak forces · Finite element model · Skull fracture * Caroline Deck deck@unistra.fr 1 Université de Strasbourg ICube, UNISTRA-CNRS, 2 rue Boussingault, 67000 Strasbourg, France 2 Department of Neurosurgery, Medical College of Wisconsin, 9200 West Wisconsin Avenue, Milwaukee, WI 53226, USA