F.A.O. Fernandes

Motorcycle helmets—A state of the art review

This paper tries to make an overview of the work carried out by scientific community in the area of road helmets safety. In an area that is constantly being pushed forward by market competition, self-awareness of danger and tighter standards, several research groups around the world have contributed to safety gear improvement. In this work concepts related to head impact protection and energy absorption are explained. It also makes reference to the theories related to the development of helmets, as well as to the different existing types nowadays. The materials that are typically used in impact situations and new design concepts are also approached. In addition, it is presented a literature review of current--and most commonly used--helmet test standards, along with new tests and helmet concepts to assess the effects of rotational motion. In a non-restrictive, and never up-to-date report, a state-of-art review on road helmets safety is done, with a special insight into brain injury, helmet design and standards.

Head injury predictors in sports trauma--a state-of-the-art review.

Head injuries occur in a great variety of sports. Many of these have been associated with neurological injuries, affecting the central nervous system. Some examples are motorsports, cycling, skiing, horse riding, mountaineering and most contact sports such as football, ice and field hockey, soccer, lacrosse, etc. The outcome of head impacts in these sports can be very severe. The worst-case scenarios of permanent disability or even death are possibilities. Over recent decades, many In recent decades, a great number of head injury criteria and respective thresholds have been proposed. However, the available information is much dispersed and a consensus has still not been achieved regarding the best injury criteria or even their thresholds. This review paper gives a thorough overview of the work carried out by the scientific community in the field of impact biomechanics about head injuries sustained during sports activity. The main goal is to review the head injury criteria, as well as their thresholds. Several are reviewed, from the predictors based on kinematics to the ones based on human tissue thresholds. In this work, we start to briefly introduce the head injuries and their mechanisms commonly seen as a result of head trauma in sports. Then, we present and summarize the head injury criteria and their respective thresholds.

Computer Simulations for Head Injuries Verification After Impact

The paper describes an experimental and numerical approach to head injury verification occurring in transportation accidents. Current trends in pedestrian, cyclist and motorcyclist safety are presented and some state-of-the-art techniques are included to mitigate injuries, which occur when an external force traumatically damages the brain. Finally, a finite element analysis was conducted to assess the safety performance of a commercial motorcycle helmet.

Development and validation of a new finite element human head model: Yet another head model (YEAHM)

Purpose Currently, there are some finite element head models developed by research groups all around the world. Nevertheless, the majority are not geometrically accurate. One of the problems is the brain geometry, which usually resembles a sphere. This may raise problems when reconstructing any event that involves brain kinematics, such as accidents, affecting the correct evaluation of resulting injuries. Thus, the purpose of this study is to develop a new finite element head model more accurate than the existing ones. Design/methodology/approach In this work, a new and geometrically detailed finite element brain model is proposed. Special attention was given to sulci and gyri modelling, making this model more geometrically accurate than currently available ones. In addition, these brain features are important to predict specific injuries such as brain contusions, which usually involve the crowns of gyri. Findings The model was validated against experimental data from impact tests on cadavers, comparing the intracranial pressure at frontal, parietal, occipital and posterior fossa regions. Originality/value As this model is validated, it can be now used in accident reconstruction and injury evaluation and even as a design tool for protective head gear.

Mechanical Properties of Natural Cellular Materials

Natural cellular materials can be found nearly everywhere in nature: from wood to leaves and cork or looking at the human bone, these structures have been studied more intensively over the last decades. Some of them have been showing exceptional mechanical properties that can compete or even surpass their synthetic competitors. The following sections plan to give a concise overview of some of these materials and their mechanical properties.

Validation of YEAHM

This chapter presents the validation of a new and geometrically detailed FEHM against experimental data from impact tests on cadavers. YEAHM was validated against experimental data from impact tests on cadavers performed by Nahum et al. (1977), comparing the intracranial pressure at frontal, parietal, occipital and posterior fossa regions. The influence of mesh quality on the results is also analysed. In addition, YEAHM was also validated in terms of brain intracranial motion by simulating the impact performed by Hardy et al. (2001). In this, ten different points in the brain were tracked in terms of relative displacement in two directions. Since YEAHM is validated, it can be used as an injury evaluation tool in accident reconstructions, in forensic cases and even in the design of protective head gear.

Development of a New Finite Element Human Head Model

This chapter presents the modelling of a new and geometrically detailed FEHM. This model stands out by its brain with sulci and gyri structures. Several steps were necessary to model it, specially the geometry based on medical images. Material modelling and proper contact definition were also necessary to develop the head model. In addition, the contact definition used for this model allows the brain to move inside the skull, which makes this model more realistic.

Finite Element Head Modelling and Head Injury Predictors

This chapter presents a state-of-the-art review on finite element head modelling. In addition, it also includes a review about the parameters used as head injury criteria with finite element head models as well as their respective thresholds. The head injury criteria and the thresholds here summarised are the result of a great number publications available in the literature. These are the output from experimental and numerical research works. The injury thresholds presented in the latter were generally obtained through accident reconstructions with finite element head models. An overview of their evolution over the last decades and an assessment of the more complex ones are also presented.

Application of Numerical Methods for Accident Reconstruction and Forensic Analysis

Accident reconstructions and numerical simulations are used to evaluate and improve protective systems as a complement to other methods, such as epidemiological and experimental studies. This chapter sets out how the virtual testing and numerical methods can contribute in vulnerable road user forensic science and injury biomechanics. The utilisation of virtual simulations has been continuously evolving, yet it still requires some accuracy enhancements, particularly in components and material modelling. Currently, numerical simulations constitute the basis for the Computer-Aided Engineering—numerical models can reflect the tissue-level response to provide information about location and severity of injury. The expansion of numerical simulations enables widening the possibilities and application field including vulnerable road user safety in terms of a collision with a motor vehicle. Although the physical validation of a test tends to be costly, it assesses whether potential development can be made in terms of safety enhancement. The accident data determines the quality of the accident reconstructions, which in turn lays the foundations for the evaluation of FE models. This chapter presents the tremendous potential of using computer-aided engineering and describes the numerical approach to head injury verification occurring in a real-world transportation accident, particularly a complex lawsuit that have been already investigated by many accident reconstructionists, experts and witnesses who were called by various court instances.