A review of contemporary techniques for measuring ergonomic wear comfort of protective and sport clothing

Protective and sport clothing is governed by protection requirements, performance, and comfort of the user. The comfort and impact performance of protective and sport clothing are typically subjectively measured, and this is a multifactorial and dynamic process. The aim of this review paper is to review the contemporary methodologies and approaches for measuring ergonomic wear comfort, including objective and subjective techniques. Special emphasis is given to the discussion of different methods, such as objective techniques, subjective techniques, and a combination of techniques, as well as a new biomechanical approach called modeling of skin. Literature indicates that there are four main techniques to measure wear comfort: subjective evaluation, objective measurements, a combination of subjective and objective techniques, and computer modeling of human–textile interaction. In objective measurement methods, the repeatability of results is excellent, and quantified results are obtained, but in some cases, such quantified results are quite different from the real perception of human comfort. Studies indicate that subjective analysis of comfort is less reliable than objective analysis because human subjects vary among themselves. Therefore, it can be concluded that a combination of objective and subjective measuring techniques could be the valid approach to model the comfort of textile materials

Human environmental heat transfer simulation with CFD – the advances and challenges

The modelling and prediction of human thermoregulatory responses and comfort have gone a long way during the past decades. Sophisticated and detailed human models, i.e. the active multi-nodal thermal models with physiological regulatory responses, have been developed and widely adopted in both research and industrial practice. The recent trend is to integrate human models with environmental models in order to provide more insight into the thermal comfort issues, especially in the non-homogeneous and transient conditions. This paper reviews the logics and expectations of coupling human models with computational fluid dynamics (CFD) models. One of main objectives of such approaches is to take the advantage of the high resolution achievable with the CFD, to replace the empirical methods used in the human models. We aim to initiate debates on the validity of this objective, and to identify the technical requirements for achieving this goal. A simple experiment with 3D human models of different sizes and shapes is also reported. Initial results shows the presence of arms may be important. Further experiments are required to establish the impact of size and shape on simulation result

The effect of condensation in clothing on heat transfer

A condensation theory is presented, that enables the calculation of the rate of vapour transfer with its associated effects on temperature and total heat transfer, inside a clothing ensemble consisting of underclothing, enclosed air, and outer garment. The model is experimentally tested by three experiments: I impermeable garments worn by subjects with and without plastic foil around the skin, blocking sweat evaporation underneath the clothing; 2 comparison of heat loss in impermeable and semipermeable garments and the associated discomfort and strain; 3. subjects working in impermeable garments in cool and warm environments at two work rates, with and without external radiation, until tolerance. The measured heat exchange and temperatures are calculated with satisfying accuracy by the model (mean error - 11, sd - 10 W/m2 for heat flows and .3 and .9 °C for temperatures, respectively). A numerical analysis shows that for total heat loss the major determinants are vapour permeability of the outer garment, skin vapour concentration, air temperature and clothing insulation. In the cold the condensation mechanism may completely compensate for the lack of permeability of the clothing as far as heat dissipation is concerned, but in the heat impermeable clothing is more stressful

Air gaps in protective clothing during flash fire exposure

Protective clothing is widely used in many industries and applications to provide protection against fire exposure. Exposure to fire can result in skin burn injuries that range from first-degree to third-degree burn injury depending on the exposure intensity and duration. Within the firefighting community, and especially the petroleum and petrochemical industries flash fire is one of the possible fire hazards for workers. Exposure to flash fire is usually of short duration (a few seconds) until the worker runs away from the fire location. The typical protective clothing system consists of a fire resistant fabric, the human skin, and an air gap between the fabric and skin. The protective performance of the clothing is evaluated based on the total energy transfer from the fabric to the skin through the air gap causing burn injury to the skin. Therefore the air gap between the protective clothing and skin plays an important role in determining the protection level provided by the clothing since the energy transfer through the air gap determines the amount of energy received by the skin. The more realistic the analysis of the air gap, the more reliable the evaluation of the protective performance of the clothing. This study introduces a more realistic analysis for the air gap between protective clothing and the skin compared to that found in the literature. More specifically, the study accounts for the combined conduction-radiation heat transfer through the air gap, which was treated as a thermal radiation participating medium with temperature dependent thermophysical properties. A finite volume model was developed to simulate the transient heat transfer in a single layer protective clothing system with radiation heat transfer. The model was employed to investigate the influence of the conduction-radiation heat transfer through the air gap on the overall heat transfer through the protective clothing system and hence on its protective performance. The influence of different protective clothing parameters on the combined conduction-radiation heat transfer through the air gap such as the air gap absorption coefficient, air gap width, fabric thickness, and fabric backside emissivity was studied. A comprehensive study of the influence of a periodic variation in the air gap width and associated inflow of cool air due to the motion of the person wearing the clothing on its protective performance was carried out. A wide range of variation in the frequency and amplitude of the fabric periodic movement was considered to capture different scenarios for the wearer’s motion. Finally, a finite volume model was developed to simulate the transient heat transfer in multiple layers firefighters’ protective clothing. The model considered the combined conduction-radiation heat transfer in the air gaps entrapped between the clothing layers, which were treated as thermal radiation participating media. The influence of each air gap on the overall performance of the clothing was investigated as well. The improved air gap model is a significant improvement for modeling heat transfer in protective clothing. It was used to obtain a more detailed knowledge of the theoretical performance of such clothing, e.g. it was found that reducing the fabric backside emissivity was more effective in improving the clothing protective performance than increasing the fabric thickness. It was also observed that the motion of the person wearing the clothing has a significant effect on the performance of the clothing: an increase in the frequency of the fabric movement improves the protection provided by the clothing, primarily due to the more frequent inflow of cool air, while an increase in the amplitude of the fabric movement reduces the protection provided by the clothing by concentrating the exposure on the skin. Finally, the air gaps entrapped between the clothing layers in firefighters’ protective clothing were found to improve the clothing performance, and the influence of the air gap between the moisture barrier and the thermal liner is greater than that of the air gap between the outer shell and the moisture barrier

Oral application of L-menthol in the heat: From pleasure to performance

When menthol is applied to the oral cavity it presents with a familiar refreshing sensation and cooling mint flavour. This may be deemed hedonic in some individuals, but may cause irritation in others. This variation in response is likely dependent upon trigeminal sensitivity toward cold stimuli, suggesting a need for a menthol solution that can be easily personalised. Menthol’s characteristics can also be enhanced by matching colour to qualitative outcomes; a factor which can easily be manipulated by practitioners working in athletic or occupational settings to potentially enhance intervention efficacy. This presentation will outline the efficacy of oral menthol application for improving time trial performance to date, either via swilling or via co-ingestion with other cooling strategies, with an emphasis upon how menthol can be applied in ecologically valid scenarios. Situations in which performance is not expected to be enhanced will also be discussed. An updated model by which menthol may prove hedonic, satiate thirst and affect ventilation will also be presented, with the potential performance implications of these findings discussed and modelled. Qualitative reflections from athletes that have implemented menthol mouth swilling in competition, training and maximal exercise will also be included

COMPUTER–AIDED CLOTHING ERGONOMIC DESIGN FOR THERMAL COMFORT

Ergonomija je definirana kao znanstvena disciplina koja proučava interakcije između ljudi i ostale elemente sustava, te kao profesija koja primjenjuje teoriju, načela, podatke i metode dizajna kako bi optimizirala ljudsko stanje i ukupnu aktivnost sustava. Odjeća je ključna za ljudsku dobrobit, postojanje i preživljavanje, što uključuje proučavanje ljudi i njihovu okolinu, uključujući antropometriju, biomehaniku, tekstilno inženjerstvo, kineziologiju, fiziologiju, termofiziologiju i psihologiju. Odjeća pruža prenosivo, osobno toplinsko okruženje bitno za preživljavanje u ekstremnim uvjetima te utječe na zdravlje i obolijevanje ljudi u svakodnevnom životu. Ergonomijski dizajn za termičku udobnost uključuje integraciju multidisciplinarnog znanja i predstavlja jedan kompleksan i dugi proces koji se zasniva na pokušajima i pogreškama u tradicionalnom značenju. Primjenom matematičkih modela, računalnih algoritama, baze podataka i povećanjem moći računala i popularnosti, možemo dizajnirati i konstruirati odjevne predmete za termičku udobnost na učinkovit, ekonomičan i znanstveni način pomoću naprednog CAD sustava. Ovaj rad prikazuje virtualni CAD sustav za ergonomijsko dizajniranje termičkih svojstava odjeće. CAD sustav formira virtualni prostor za dizajnere i inženjere za dizajn, razvija odjevni predmet i prikazuje njegove termičke funkcije bez izrade stvarnog odjevnog predmeta. Termički bioinženjering i načela ergonomijskog dizajna odjeće su, također, prikazani.Ergonomics is defined as the scientific discipline concerned with the understanding of interactions among humans and other elements of a system, and the profession that applies theory, principles, data and methods to design in order to optimize human well-being and overall system performance. Clothing is an essential means for human well-being, existence and survival, which involves study of humans and their environments, including anthropometry, biomechanics, textile engineering, clothing engineering, kinesiology, physiology, thermophysiology and psychology. Clothing provides a portable and personalized thermal environment that is critically important for human survival in extreme conditions and determines the health and sickness of human populations in daily life. Ergonomic design for thermal comfort involves the integration of multidisciplinary knowledge and has been a complex and long process of trial-and-error in traditional means. Utilizing proper mathematic models, computational algorithms, databases and increasing computer power and popularity, we can design and engineer apparel products for thermal comfort in an effective, economical and scientific way by using advanced CAD system. This paper presents a virtual thermal ergonomic CAD system for ergonomic design of clothing, which creates a virtual space for designers and engineers to design and develop apparel products and view their thermal functional performance without making the real garment samples. The thermal bioengineering framework and clothing ergonomic design principles are presented with case demonstrations

Textile Manufacturing Processes

Textile manufacturing is an important subject in textile programs and processing industries. The introduction of manmade and synthetic fibers, such as polyester, nylon, acrylic, cellulose, and Kevlar, among others, has greatly expanded the variety of textile products available today. In addition, new fiber development has brought about new machines for producing yarns, fabrics, and garments. Textile Manufacturing Processes is a collection of academic and research work in the field of textile manufacturing. Written by experts, chapters cover topics such as yarn manufacturing, fabric manufacturing, and garment and technical textiles. This book is useful for students, industry workers, and anyone interested in learning the fundamentals of textile manufacturing

Clothing Evaporative Resistance: Its Measurements and Application in Prediction of Heat Strain

Clothing evaporative resistance is one of the most important inputs for both the modelling and for standards dealing with thermal comfort and heat stress. It might be determined on guarded hotplates, on sweating manikins or even on human subjects. Previous studies have demonstrated that the thermal manikin is the most ideal instrument for testing clothing evaporative resistance. However, the repeatability and reproducibility of manikin wet experiments are not very high for a number of reasons such as the use of different test protocols, manikins with different configurations, and different methods applied for calculation. The overall goals of the research presented were: (1) to examine experimental parameters that cause errors in evaporative resistance and to set up a well-defined test protocol to obtain repeatable data; and (2) to apply the reliable clothing evaporative resistance data obtained from manikin measurements and physiological data acquired from human trials to validate the Predicted Heat Strain (PHS) model (ISO 7933). Most of the calculations on clothing evaporative resistance up until now have been based on manikin temperature rather than fabric skin temperature because the fabric skin temperature was unknown. However, the calculated evaporative resistance has been overestimated because the fabric skin temperature is usually lower than the manikin temperature. This is mainly due to that water evaporation cooling down the fabric skin. In Paper I, the error of using manikin temperature instead of fabric skin temperature for evaporative resistance calculation was examined. In Paper II, a universal empirical equation was developed to predict wet skin temperature based on the total heat loss obtained from the manikin and the controlled manikin temperature. Paper III investigated discrepancy between the two options for the calculation of clothing evaporative resistance and how to select one of them for measurements conducted in a so called isothermal condition. Paper IV studied localised clothing evaporative resistance through an inter-laboratory study. The localised dynamic evaporative resistance caused by air and body movement was examined as well. In addition, reduction factor equations for localised evaporative resistance at each local segment were established. The thermophysiological responses of eight human subjects who wore five different vocational garments in various warm and hot environments were investigated (Paper V and Paper VI). The PHS model was validated by those human trials. Some suggestions on how to revise this model in order to achieve wider applicability were discussed and proposed. The results showed that the prevailing method for the calculation of evaporative resistance can generate an error of up to 35.9% on the boundary air layer’s evaporative resistance Rea. In contrast, it introduced an error of up to 23.7% to the clothing total evaporative resistance Ret. The error was dependent on the value of the clothing intrinsic evaporative resistance Recl. The isothermal condition is the most preferred test condition for measurements of clothing evaporative resistance; the isothermal mass loss method is always the correct option to calculate evaporative resistance. The reduction equations developed for localised clothing evaporative resistance have demonstrated that a total evaporative resistance value provided very limited information for local clothing properties and thus, localised values should be reported. The skin temperatures predicted by the PHS model were greatly overestimated in light clothing and high humidity environments (RH>80%). Similarly, the predicted core temperatures in protective clothing FIRE in warm and hot environments were also largely overestimated. The predicted evaporation rate was always much lower than the observed data. Therefore, a further revision of this model is required. This can be achieved by performing more human subject tests and applying more sensitive mathematical equations