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- Aljaste, Helena, et al.
(författare)
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Better bicycle helmets for commuters – evaluation of ventilation
- 2014
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Ingår i: International Cycling Safety Conference 2014.
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Konferensbidrag (refereegranskat)abstract
- As a continuation of the work on the development of setting the requirements for ventilation of a bicycle helmet for commuters, 15 full scale helmet mock-ups were created by the students of the Estonian Academy of Arts. In order to encourage creativity for ventilation solutions the students were not restricted to consider the other properties except it was pointed out that the meaning of helmets use is protection. These 1:1 scaled mock-ups were tested at Thermal Environment Laboratory, Lund University for their heat transfer characteristics (insulation) in a wind tunnel on a thermal head manikin. The helmets were tested at the room temperature with the air velocities of 0.2, 1.6 and 6.0 m/s. The air velocities of 0.2 and 1.6 m/s were tested without a wig and 1.6 and 6.0 m/s were tested with wig to simulate the effect of hair. In addition, 4 reference helmets were tested in some conditions. Three (3) of them were one of the best, one average and one of the less well performing helmets of an earlier study, and one was a helmet commonly bought and used by an ordinary bicyclist. The helmets in new design were affected by ventilation and covered a wide range of insula-tion. The reference helmets from the earlier study stayed quite in the middle of the tested range. Thus, the new solutions could work much better or worse than available helmets. However, practically any new helmet was better than the common helmet from the shop. It was also very clear that various air velocities affected heat loss from the helmets. This means that a best solution for a commuter has to be defined by the user’s bicycling velocity. The best ventilation solutions will be chosen and the design work with considering of impact testing will be continued.
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| 2. |
- Aljaste, Helena, et al.
(författare)
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The effects of air channel construction and design elements on heat transfer characteristics of bicycle helmets for commuters
- 2015
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Ingår i: International Cycling Safety Conference 2015.
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Konferensbidrag (refereegranskat)abstract
- The earlier studies in this measurement series defined the limits and aims for design process to create better ventilating helmets [1], and tested the insulation [2] and evaporative characteristics [3] of the designed mock-ups. In addition some of the tested mock-ups were modified to study more closely the factors that were expected to improve heat transfer from the bicycle helmets. The present paper covers making a new prototype that allowed modifications of the air channels and in- and outlet openings. In total 2 new helmet design concept mock-ups were created and tested with 13 modifications in comparison with 6 selected helmets from the previous studies including the modified versions. The mock-ups were tested at the Thermal Environment Laboratory, Lund University for insulation and evaporative resistance. Dry tests for insulation were carried on at 20 °C temperature in a wind tunnel on a thermal head manikin at the chosen air velocities of 1.6 m/s on a bald head and 1.6 m/s and 6 m/s with the wig in order to simulate the effect of hair. Wet tests were carried out with textile skin on the head manikin, using the air velocity 1.6 m/s with and without the wig. As the main result it was concluded that a well ventilating helmet is characterized by less contact with the head, and proper air channels with strategically placed air inlets and outlets. Large openings worked much better than a several small ones, yet, the care has to be taken as too large openings reduce the helmet protective capabilities. The shape and other design related modifications of the air inlets and outlets had minimal effect on ventilation.
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| 3. |
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| 4. |
- Kuklane, Kalev, et al.
(författare)
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User friendly bicycle helmet for commuters
- 2013
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Konferensbidrag (refereegranskat)abstract
- The number of adult bicycle helmet users in Sweden has stayed over the years relatively stable around 20 % [1]. In Europe the number of helmet users varies between 1 and 40 % depending on country. Research has shown that the use of helmet considerably diminishes head injuries in the case of traffic accidents [2]. In spite of that it is not fully clear what are the main factors why only a small number of bicyclists use a helmet. In order to raise awareness of helmet use and improve traffic safety COST Action supported a European initiative “Towards safer bicycling through optimization of bicycle helmets and usage”. Why helmet use is not popular? Several reasons could be pointed out: design, destroys the hair style, attitudes against helmet use, nowhere to put, too warm etc. Often the initial complaints are related to heat [3]. In cold additional insulation from the helmet may be a positive factor while compatibility issues may rise. As the professional bicyclists and most training/competing amateurs do wear the helmets then the aim for traffic safety should be increasing helmet use among commuters and bicyclists who do it just for fun. Therefore a project was initiated where main issue was to reduce initial thermal disturbance from a bicycle helmet while keeping in mind visibility, protection aspects, look, issues related to wearing comfort etc. Some relevant factors to be considered are: • The motion speeds of commuters would stay on average around 15 km/h (4.2 m/s) with average high speed not much above 20 km/h. • Aerodynamics and placement of the vents and air channels. • The effect of hair should not be underestimated – these may fill air channels with very effective insulation material.
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