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In Taiwan, a motorcycle is the most important and general transportation. It is no denying that wearing a motorcycle helmet could prevent the rider from head injuries in the accidents. However, the ventilation of helmets still has to be improved. This study aims to set several ventilation channels in the energy absorption liner. They apply the Venturi effect to increase the ventilation of helmets. But it may affect the protection performance of helmet. The purpose of this study is to estimate the protective ability of the ventilative helmet. Therefore, the various ventilative helmets are designed by the computer-aided design software SolidWorks, and simulations of the impact test of the helmet are investigated by the finite element analysis software ANSYS/LS-DYNA. In addition, the effect of using different foam material is also discussed in this study.

Plusieurs études ont montré que dans les accidents réels, la vitesse d’impact de la tête n’est que rarement normale à la surface et présente une composante tangentielle non négligeable. Aucune norme, à l’heure actuelle ne propose de choc oblique avec enregistrement de l’accélération en translation et en rotation de la fausse tête. Un aspect essentiel de cette recherche a été d’aborder les descriptions d’accidents réels impliquant un motocycliste et un véhicule afin d’évaluer les conditions aux limites de la tête juste avant impact, en termes de vecteur vitesse et de localisation d’impact. Cette étude a permis d’établir le vecteur vitesse possible et de l’angle d’impact de la tête du motocycliste en situation. Une méthode de test pour évaluer le casque a été proposée. Les tests d'impact obliques, sont effectués avec une vitesse d’impact de 8.5 m/s sur une enclume inclinée de 45° permettant la rotation autour de l’axe Y X et Z. Les accélérations 6-D sont implémentés dans le modèle SUFEHM afin d’extraire la déformation axonal maximale et le risque lésionnel. Cette fusion de la méthode expérimentale et numérique donne un avantage par rapport aux normes conventionnelles, tant en termes de conditions d’impact qu’en termes de critère de blessure de la tête. / It is well know that in case of accident the head does not only impact perpendicularly to the impacted structure but presents an oblique impact condition. However none of the today helmet standards do integrate oblique impacts with the recording of the dummy head rotational acceleration. An essential aspect of the present research is to simulate real world accident and to compute the victim’s kinematic in order to extract the head impact conditions. In collaboration with University Florence (Italy) 19 cases were considered and it was shown that the head impact velocity vector presents a significative angle. A novel helmet test method has been proposed. Helmeted headfoml is impacting a 45° inclined anvil at a speed of 8.5 m/s and the 6D acceleration versus time curves are introduced into an existing head FEM in order to compute the axon strains and to derive the brain injury risk.

[pt] O objetivo deste estudo foi comparar o teste de absorção de impacto em compósitos reforçados com fibras naturais às espumas de PU em substituição ao tradicional poliestireno expandido EPS em capacetes para motociclistas, item de segurança essencial, que tem como principal função mitigar a gravidade das lesões cranianas em acidentes. Este estudo teve como principal motivação a utilização do PU devido as suas propriedades mecânicas adaptáveis e por um processo simplificado de mistura, que torna viável a incorporação de fibras naturais como coco, sisal e bagaço de cana, em sua matriz, frente aos crescentes desafios ambientais e à necessidade urgente de sustentabilidade. A metodologia adotada incluiu a formulação de compósitos em proporções de fibras naturais selecionadas, variando de 5 a 15 por cento seguida pela realização de testes de absorção de energia de impacto. A avaliação metrológica usou ferramentas paramétricas e não-paramétricas para a comparação dos resultados da absorção de energia de impacto entre os compósitos de PU puro e aqueles reforçados com as fibras naturais selecionadas. Os resultados obtidos demonstraram uma melhoria significativa na absorção de energia de impacto ao se usar compósitos de PU reforçados com fibras naturais. Por fim, conclui-se que a adição de fibras naturais ao PU pode substituir o EPS, visto que, metrologicamente, não houve prejuízo na absorção de energia de impacto, além da contribuição para a responsabilidade ambiental. / [en] The purpose of this study was to compare the impact absorption test of fiber-reinforced composites with natural fibers to expanded polyurethane (PU) foams as a substitute for traditional expanded polystyrene (EPS) in motorcycle helmets, an essential safety item whose primary function is to mitigate the severity of cranial injuries in accidents. This study was principally motivated by the use of polyurethane (PU) due to its adaptable mechanical properties and a simplified mixing process, which enables the incorporation of natural fibers such as coconut, sisal, and sugarcane bagasse into its matrix, in response to the growing environmental challenges and the urgent need for sustainability. The methodology employed included the formulation of composites in varying proportions of selected natural fibers, ranging from 5 to 15 percent, followed by the execution of impact energy absorption tests. The metrological evaluation utilized parametric and non-parametric tools to compare the impact energy absorption results between pure PU composites and those reinforced with selected natural fibers. The results demonstrated a significant improvement in impact energy absorption when using PU composites reinforced with natural fibers. In conclusion, the addition of natural fibers to PU can replace EPS; since, metrologically, there was no detriment to impact energy absorption, in addition to contributing to environmental responsibility.

International organisations such as the World Health Organisation highlight the road crash problem in less motorised (or developing, or low income) countries like those in Southeast Asia and recommend the adoption of Western road safety measures. However, there are many differences between highly motorised and less motorised countries which raise questions about how successfully Western road safety knowledge and expertise can be transferred.----- A review of the statistical information on road crashes shows a great deal of uncertainty about both the scale and likely trajectory of road fatalities globally, in less motorised countries and in Asia. It is generally agreed, however, that Asia accounts for around half of all road fatalities, and analysis of the limited available data shows both that Southeast Asia is not an atypical region of Asia in road safety terms, and that Thailand and Vietnam are not atypical of Southeast Asian countries.----- A literature review of recommended practice approaches to road safety transfer in Asia shows that there are many economic, institutional, social and cultural factors which potentially influence the success of transfer. The review also shows that there is no coherent, comprehensive approach which either conceptualises these factors and their relationship to transfer outcomes, or uses an analysis of these factors to plan or modify transfer. To address this gap, this thesis develops a 'road safety space' model as a tool for conceptualisation and analysis, based on a biological metaphor which views the transfer of road safety measures from one context to another as analogous to the transfer of a species into a new ecological space. The road safety space model explicitly considers economic, institutional, social and cultural factors (from specific to broad) which influence the particular road safety issue which a particular road safety transfer effort seeks to address. A central contention of this thesis is that the road safety space model is both a feasible and useful tool to improve the process of road safety transfer to less motorised countries. Road safety space analysis is seen to have a role in a broader process of selection of road safety measures for transfer, along with knowledge of how the measures are considered to operate.----- The research reported in this thesis is comprised of three studies. Study 1 reviewed evaluations of road safety transfer to Thailand and Vietnam. Studies 2 and 3 were case studies of road safety transfer to Thailand and Vietnam respectively.----- Study 1 was an analysis of existing evaluations of road safety transfer to Thailand and Vietnam. The aims were to analyse the evaluations for their consideration of contextual factors, as described in the road safety space model, and to discuss whether the road safety space model assisted in understanding the reasons for success or failure of transfer. However, very few such evaluations exist, and those that were found generally lacked information on whether contextual factors were considered. This indicated the need for a more detailed, in-depth qualitative investigation of particular cases of road safety transfer, in order to investigate the feasibility and utility of the road safety space model.----- Two case studies (Study 2 and Study 3) were conducted to test whether the road safety space approach was both feasible and useful as a means of improving road safety transfer efforts. Study 2 was a case study of the development and implementation in Thailand of a road safety education program for school children, which involved the transfer of Western research and techniques. The transfer agents (i.e. those who effected the road safety transfer) were Australian consultants working for the Australian Road Research Board (ARRB). The transfer was funded by the World Bank and managed by the Thai Ministry of Education (MOE). Study 3 was a case study of the development and implementation of a motorcycle helmet wearing program in Vietnam, which involved the transfer of Western knowledge, techniques and technology. The transfer agents were staff of Asia Injury (AI), a non-government organisation (NGO), and the program was funded initially by a charitable fund, with the intention of becoming self-funding through operation of a helmet factory.----- The case studies employed background research into existing information on economic, institutional, social and cultural factors relevant to the road safety issues (road use behaviour of school children in Thailand and motorcycle helmet purchase and wearing in Vietnam), and collected data through interviews with key informants, analysis of secondary sources and observations. This information was used to derive the road safety space for each road safety issue, to identify the road safety space recognised and addressed by the transfer agents (ARRB and AI), and to determine which factors they missed, or were aware of but took no action on. The focus of this analysis was on the processes used in transfer, not on the road safety outcomes of transfer, although these provided information on the processes as well. Available evaluation information was used to draw links between the omissions and the success of the transfer processes. It was noted that information on how the transferred measures operate should come from a road safety space analysis in the originating country, although this raised questions about selection of country and time (when the measure was first introduced, or in its maturity).----- The feasibility and utility of the road safety space model were discussed. It was clear that the model provided information on the cases which was missed by the transfer agents. The questions examined next were whether this information could have been obtained from an exercise conducted before the transfer had commenced, whether the required effort and cost justified the potential benefits, and whether the information on the road safety space could have been useful for the transfer agents. Comparisons between the road safety spaces for the two cases showed some areas of commonality, e.g. perceptions of police corruption, but also many differences. It was considered likely that some broad factors could be generic, and the possibility was mooted that less motorised countries share issues with police enforcement. This requires further research, however, and at this stage it is better to treat each road safety space as a unique combination of contextual factors influencing the road safety issue of interest.----- It is concluded that the road safety space model is feasible if used in such a way as to minimise the research involved, and useful, although the degree of utility needs to be further explored in a prospective study. The limitation introduced by restricting informants to those who could speak English are discussed. An approach using road safety space analysis is recommended, emphasising analysis of the country to which the road safety measure is being transferred, supplemented by analysis of the originating country road safety space. Gaps in knowledge are identified for further research and development, in particular the theoretical and practical understanding of road use behaviours and their modification in less motorised countries in Southeast Asia. Elaboration of the model is also recommended, to take into account the influence of the type of measure transferred, the role of the transfer agent, the area of road safety (education, engineering or enforcement), and the time dimension (the time which might be needed for a transfer to show its effects).----- The findings of this research are likely to be applicable to road safety transfer in other less motorised regions of the world, however prospective testing is needed. They may also be relevant to issues of transfer for areas other than road safety, in particular public health and traffic engineering, where similar economic, institutional, social and cultural issues come together.