Thermal Perception of Ventilation Changes in Full-Face Motorcycle Helmets: Subject and Manikin Study

We report the effects of full-face motorcycle helmet ventilation systems on heat, airflow, noise, and comfort perception for ventilation changes on the scalp. Eight subjects (aged 28.0 ± 5.4 years) underwent two experimental trials at ambient temperatures of 23.7 ± 0.4°C or 27.5 ± 0.3°C. In each trial, the thermally equilibrated subjects underwent two examination phases, during which four different helmets were assessed at wind speeds of 39.2 ± 1.9 km h−1 and 59.3 ± 1.4 km h−1. Vent-induced heat loss in the scalp ranged from −6.1 to 6.1 W, corresponding to vents being closed or opened, respectively. Perception of vent-induced changes was assessed immediately after the change. We find that the vent-induced heat loss, the subject, and the helmet are the most important response factors. In addition, comparison of two helmets with similar vent-induced heat loss suggests that internal airflow patterns may be important in explaining the observed perception difference

The Effect of Two Sock Fabrics on Perception and Physiological Parameters Associated with Blister Incidence: A Field Study

The goal of the present study was to investigate differences in perception and skin hydration at the foot of two sock fabrics with distinct moisture properties in a realistic military setting. Thirty-seven military recruits wore two different socks (PP: 99.6% polypropylene and 0.4% elastane, and BLEND: 50% Merino-wool, 33% polypropylene, and 17% polyamide), one on each foot. Measurements were carried out after a daily 6.5-km march on 4 days. Each participant rated temperature, dampness, friction, and comfort for each foot. On a daily selection of participants, skin hydration was measured on three sites of both feet using a corneometer, and moisture content of the socks was determined. BLEND was rated to be cooler, less damp, and more comfortable (P < 0.05). Two out of three skin sites were drier for BLEND than PP (P < 0.05). Moreover, BLEND stored 2.9 ± 0.3 times more moisture compared to PP. Thus, under the present conditions, socks such as BLEND are to be preferred over polypropylene sock

PHYSIOLOGICAL EFFECTS AFTER EXPOSURE TO HEAT: A BRIEF LITERATURE REVIEW

Many employees are exposed to heat stress during their work. Although the direct effects of heat are well reported, the long term physiological changes after heat exposure are hardly described. The present manuscript addresses these issues in the form of a brief literature review. Repeated heat exposure results in heat acclimatization, these physiological adaptations decay gradually afterwards, re-increasing the vulnerability to heat injuries. Repeated heat exposure may lead to kidney damage (related to dehydration) and reduced efficiency of the reproductive system. A history of heat stroke may increase the sensitivity to heat illness. The increased susceptibility possibly indicates an impaired thermoregulatory system resulting from a heat stroke, or a genetic predisposition prior to the first heat stroke

Thermal Perception of Ventilation Changes in Full-Face Motorcycle Helmets: Subject and Manikin Study

ISSN:0003-4878ISSN:1475-316

Final report of Working Group 4: Ergonomics of thermal effects. A COST Action TU1101 / HOPE collaboration

The thermal effects related to wearing a bicycle helmet are complex and different studies have investigated single parts of this topic. A literature review was produced and published (Bogerd et al., 2015) summarizing the different findings to give a complete overview on this topic as well as to suggest new perspectives. Headgear increases head insulation and therefore is mainly problematic under warm conditions, which is the focus of that review. Helmets do not affect physiological parameters other than the local skin temperature and sweat rate. However, the head is among the most sensitive body parts related to thermal comfort, thereby directly affecting the willingness to wear headgear. Several methods have been used to study thermal aspects of headgear, which could be categorized as (i) numerical, (ii) biophysical, (iii) combined numerical and biophysical, and (iv) user trials. The application of these methods established that heat transfer mainly takes place through radiation and convection. Headgear parameters relevant to these heat transfer pathways are reviewed and suggestions are provided for improving existing headgear concepts and developing new concepts, ultimately leading to more accepted headgear. The report of working group 4 (WG4) provides information about activities undertaken during the COST Action TU1101 “Towards safer bicycling through optimization of bicycle helmets and usage” to better understand the ergonomics of thermal aspects and to work towards the tasks defined in the memorandum of understanding (COST Secretariat, 2011). Primary Task 5: Development of guidelines for thermally-optimized helmet designs Secondary Task 3: Inform impact studies on which kinds of ventilation structures are useful and which are unnecessary Secondary Task 7: Review of physiological and comfort effect of wearing bicycle helmets All the chapters listed below include important aspects contributing to the primary task 5. Modelling and simulation tools (Chapter II) are becoming more and more important in research and development of new bicycle helmets but also in the development of guidelines, directives and norms. An example for the industrial application of models is given in Chapter III. The investigation of different forms of helmet coverings provides important information about the future direction for the development of helmet designs. Completely new helmet designs and the respective thermal properties are presented in Chapter IV. This chapter shows a different approach for finding new concepts of helmet designs. In Chapter V, new project initiatives are introduced to improve thermal aspects of helmets but also to include information and communication techniques (ICT) into helmets. Finally, the tasks of WG4 are summarized in Chapter VI, conclusions are drawn and an outlook is provided regarding the future development of helmets to comply with the requests of two-wheel commuters (including e-bikes, segway and others)