A Novel Instrumented Human Head Surrogate for the Impact Evaluation of Helmets

Abstract

Abstract:A novel Human Head Surrogate was obtained from available MRI scans of a 50th percentile male human head. Addictive manufacturing was used to produce the skull, the brain and the skin. All original MRI geometries were partially smoothed and adjusted to provide the best biofidelity compatible with printing and molding technology. The skull was 3D-printed in ABS and ten pressure sensors were placed into it. The brain surrogate was cast from silicon rubber in the 3D-printed plastic molds. Nine tri-axial accelerometers (placed at the tops of the lobes, at the sides of the lobes, in the cerebellum and in the center of mass) and a three-axis gyroscope (at the center of mass) were inserted into the silicon brain during casting. The cranium, after assembly with brain, was filled with silicon oil mimicking the cerebral fluid. Silicon rubber was cast in additional 3D-printed molds to form the skin surrounding the cranium. The skull base was adapted to be compatible with the Hybrid-III neck and allow the exit of brain sensors cabling. Preliminary experiments were carried out proving the functionality of the surrogate. Results showed how multiple accelerometers and pressure sensors allowed a better comprehension of the head complex motion during impacts.

Review of Auxetic Materials for Sports Applications: Expanding Options in Comfort and Protection

“…Scientific literature highlights limitations in standards, as well as associated certified products including helmets [69,[79][80][81], back protectors [18,50] and wrist protectors [51,84,85]. Recent trends look to include the use of more representative surrogates rather than rigid anvils [84,86,87] and tests designed for specific sports [50,51] to replace proxy standards (e.g., [61]). Solutions including novel materials are needed to reduce the effect of sports injuries and meet required improvements to standards (i.e., as per BSI 6685-1985 [71] and BS7928:2013 [72]).…”

Feasibility of using a novel instrumented human head surrogate to measure helmet, head and brain kinematics and intracranial pressure during multidirectional impact tests

“…Its morphological biofidelity is higher than EN or ASTM headforms and of HIII dummy heads: previous tests confirmed its ability to give overall comparable results with respect to HIII headform. 28 Compared to analog experiences by Freitas et al, 24 a slightly lower skull biofidelity and a much higher sustainability of additive technology may result a preferable compromise with respect to dehydrated bone.…”

“…1i) were performed: higher energy impacts (44J) were sustained in previous comparative tests. 28 Data were simultaneously collected at 10 kHz per channel.…”

“…27 Aim of this work is to present and discuss the feasibility of using a novel Instrumented Human Head Surrogate (IHHS-1) developed in collaboration between Mid Sweden University, Östersund, Sweden and University of Padova, Italy, for the biofidelic impact investigation of helmets and the study of brain injury mechanisms. 28…”

A Novel Multi-Axial Pressure Sensor Probe for Measuring Triaxial Stress States Inside Soft Materials

“…Indeed, such materials are widely used where high flexibility and strain are required, and their instrumentation represents a challenge that could improve the measurement of the human body and wearable devices. Soft materials such as polydimethylsiloxane (PDMS) or other silicone rubbers are investigated as possible soft tissue surrogates [ 1 , 2 ], and brain surrogates made of these materials are adopted by researchers who are trying to improve the biofidelity of their physical models of the human head [ 3 , 4 , 5 , 6 ]. A biofidelic head model is needed to improve the evaluation of brain kinematics during impacts and, thus, the effectiveness of head protective gear.…”