New dummy head prototype : development, validation and injury criteria

Abstract

Head injuries cause a large proportion of fatalities to road users particularly motorcyclists. Currently, helmets are assessed using rigid headforms and criteria related to acceleration measured at the centre of the headform. This system is not representative of the human head, which comprises a brain that moves relative to the skull in an impact. Finite element techniques were used in the design, development and validation of a new dummy head prototype named Bi-mass 150. It has been constructed using a Hybrid 111 headform and comprises two masses: a skull and a mass to represent the brain attached to the skull with a damped spring system. The novel feature of this device is that it can simulate the brain -skull relative displacement at a frequency close to 150 Hz. This is the frequency recorded in tests in vivo. The prototype was made by removing mass from a Hybrid 111 dummy head and fixing to the centre a metallic mass, which simulates the brain. The two components were connected by means of a plastic element such that the natural frequency corresponded to the 150 Hz measured in-vivo. The outputs from thirteen accident reconstructions, using an instrumented helmeted headform, were used as inputs to the FE model. The results are the first part of the process to establish bi-mass related injury criteria, and, in turn, to provide a much more human-like headform for evaluating and optimising head protection systems.

The influence of impact location and angle on the dynamic impact response of a Hybrid III headform

“…Additionally, the distribution of mass for the headform is not uniform about the interface with the neckform. The moments of inertia for the Hybrid III headform are 1.590 9 10 -2 , 2.400 9 10 -2 , and 2.200 9 10 -2 kg m 2 about the x-, y-and z-axes, respectively [37]. A future study analyzing the interaction between the Hybrid III head-and neckform could provide an explanation of this result.…”

Continuum modeling of a neuronal cell under blast loading

“…Impact- and/or acceleration-induced brain traumatic injuries have already been the focus of many cellular and macroscopical studies through in vivo [3, 4, 5, 6, 7, 8, 9, 10], ex vivo [11, 12], in vitro [13, 14, 15, 16, 17], medical postanalysis [18, 19, 20] or modeling approaches [21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34]. However the specific effects of a blast—a pressure wave of finite amplitude generated by a rapid release of energy [35]—on the brain is still widely unkown.…”

The Influence of Impact Angle on the Dynamic Response of a Hybrid III Headform and Brain Tissue Deformation

“…The Hybrid III headform does not have a uniform mass distribution, which would affect the moment of the inertia of the headform. The moments of inertia of a Hybrid III headform are1.590 · 10 -2 kg· m 2 in the x-axis, 2.400 · 10 -2 kg· m 2 in the y-axis and 2.200 · 10 -2 kg· m 2 in the z-axes, with positive axes oriented frontwards, leftwards and upwards respectively [23]. A lower moment of inertia in the x-axis would contribute to the larger magnitudes of rotational acceleration seen for side impacts relative to frontal impacts.…”