Limiting Performance of Helmets for the Prevention of Head Injury

Abstract

This is a study of the theoretical optimal (limiting) performance of helmets for the prevention of head injury. A rigid head injury model and a two-mass translational head injury model are employed. Several head injury criteria are utilized, including head acceleration, the head injury criterion (HIC), the energy imparted to the brain which is related to brain injury, and the power developed in the skull that is associated with skull fracture. A helmeted head hitting a rigid surface and a helmeted head hit by a moving object such as a ball are considered. The optimal characteristics of helmets and the impact responses of the helmeted head are investigated computationally. An experiment is conducted on an ensemble of bicycle helmets. Computational results are compared with the experimental results.

Limiting Performance Analisys of a Head Protection Helmet Using Multicriteria Control Optimization

“…The boundary conditions c U , of equation ( 7), were given as to model an initial translation with a velocity of 8.5m/s, to be compatible with the study presented in reference [8], in which, the most common interval of head impact velocities in motorcycle helmets is 5,83-8,33 ms -1 . The discretized control force, appears in vector u , of equation (6). Because the temporal finite elements consider the force in the beginning, middle and the end of each of the 40 time finite element, as can be seen in equation ( 4), we have 81 control variables to be calculated in the optimal control problem, as described in the next section.…”

Optimal Impact Isolation for Injury Prevention Evaluated by the Head Injury Criterion

“…The analytical solution of this problem is presented (without proof) in [11] in connection with the crashworthy design of the car hood to reduce the head injury of a pedestrian caused by an impact against the hood. In [3], a numerical solution of a similar problem was constructed in connection with the limiting performance analysis of impact protection helmets.…”

“…The deceleration distance is minimized subject to a constraint on the HIC functional. In contrast to [3,11], the parameters of the problem -the mass of the particle, the initial velocity (impact velocity), the maximum allowable value of the HIC, and the parameter ∆ occurring in the definition of this criterionare arbitrary. Analytical expressions are obtained for the optimal control and the minimal deceleration distance.…”

Optimal control problem for head injury criterion

“…The analytical solution of this problem is presented (without proof) in [2] in connection with the crashworthy design of the car hood to reduce the head injury of a pedestrian caused by an impact against the hood. In [3], a numerical solution of a similar problem was constructed in connection with the limiting performance analysis of impact protection helmets.…”

“…The deceleration distance is minimized under the constrained value of the HIC. In contrast to [2] and [3], the parameters of the problem-the mass of the particle, the initial velocity (impact velocity), the maximum allowable value of the HIC, and the parameter Δ occurring in the de£nition of this criterion-are arbitrary. Analytical expressions are obtained for the optimal control and the minimal deceleration distance.…”