Conference PaperPDF Available

Comfort Rating for Upholstery Systems

Authors:

Abstract and Figures

Nowadays long-distance drives or sitting workplaces are normal. As consequence a human sit up to 7.5 h per day. Therefore, the comfort while seating is getting more and more important. The comfort of upholstery systems such as car seats, office chairs or upholstered furniture is influenced by different ergonomic properties in particular the thermophysiological comfort. On one hand, the thermophysiological comfort of an upholstery system can be characterized by Hohenstein Skin Model (sweating guarded hot plate) according to ISO 11092(1). With the Skin Model the specific ther-mophysiological quantities of textiles as layers are determined. Under stationary measurement of the Skin Model the water vapor resistance Ret is determined, which characterizes the insensible sweating. Higher sweating rates (sensible sweating) can be described by buffering capacity of water vapor Fd and buffering capacity of liquid sweat Kf(2, 3). In the next step a sitting human can be simulated by the sweating buttocks model or thermal, sweating manikin "Sherlock" (Newton type by Thermetrics). By combining these measurement systems with humidity sensors within in the upholstery the moisture management of an upholstery system can be determined. On the other hand, the contact area of the human on the seat and pressure distribution on the seat are important aspects which influenced the ergonomic comfort of upholstery systems, too. The pressure distribution of a sitting person can be qualified by measurements with a pressure pad. Handheld scanner systems like Ar-tec Eva, Creaform Revscan and or low-cost devices as the Kinect sensor offer the opportunity to scan objects like seats. The three-dimensional information of seats, chairs or furniture can be compared with 3D data of target groups. As a result, the contact area can be identified in regard of size and shape.
Content may be subject to copyright.
Delft, August 29th and 30th, 2019 2nd International Comfort Congress
Comfort Rating for Upholstery Systems
B. M. Woelfling1*, E. Classen1, A. Klepser1 and A. Gerhardts1
1 Hohenstein Institut fuer Textilinnovation gGmbH, Schlossteige1, 74357 Bönnigheim, Germany
* Corresponding author. Tel.: +49-7143-271-370; fax: +49-7143-271-370. E-mail address: b.woelfling@hohenstein.de
Abstract Nowadays long-distance drives or sitting workplaces are normal. As consequence a human sit up
to 7.5 h per day. Therefore, the comfort while seating is getting more and more important. The comfort of up-
holstery systems such as car seats, office chairs or upholstered furniture is influenced by different ergonomic
properties in particular the thermophysiological comfort.
On one hand, the thermophysiological comfort of an upholstery system can be characterized by Hohenstein
Skin Model (sweating guarded hot plate) according to ISO 11092(1). With the Skin Model the specific ther-
mophysiological quantities of textiles as layers are determined. Under stationary measurement of the Skin
Model the water vapor resistance Ret is determined, which characterizes the insensible sweating. Higher
sweating rates (sensible sweating) can be described by buffering capacity of water vapor Fd and buffering ca-
pacity of liquid sweat Kf(2, 3). In the next step a sitting human can be simulated by the sweating buttocks
model or thermal, sweating manikin “Sherlock” (Newton type by Thermetrics). By combining these meas-
urement systems with humidity sensors within in the upholstery the moisture management of an upholstery
system can be determined.
On the other hand, the contact area of the human on the seat and pressure distribution on the seat are im-
portant aspects which influenced the ergonomic comfort of upholstery systems, too. The pressure distribution
of a sitting person can be qualified by measurements with a pressure pad. Handheld scanner systems like Ar-
tec Eva, Creaform Revscan and or low-cost devices as the Kinect sensor offer the opportunity to scan objects
like seats. The three-dimensional information of seats, chairs or furniture can be compared with 3D data of
target groups. As a result, the contact area can be identified in regard of size and shape.
Keywords: seat comfort, comfort, 3D scanning, pressure pad, clothing physiology
1 Introduction
Comfort is not uniformly defined. From physiological point of view, comfort is a multidimensional con-
cept influenced by several factors e.g. physical, physiological, psychological and environmental aspects. One
theory says that comfort is the absence unpleasant feeling (discomfort)(4).
Nowadays the comfort while sitting is getting more and more important. Depending on the clothing the
human body is in direct contact with the upholstery system e.g. vehicle seat, office chair, couch. More pre-
cisely shoulders, back, buttocks, thighs and lower legs have contact areas with such an upholstery system.
Further long-distance drives or sitting workplaces are getting normal. As consequence a human sit up to 7.5 h
per day(5). Hence, the comfort of upholstery systems is important. For the comfort characterisation of uphol-
stery systems while sitting different aspects should be considered: sensorial, thermophysiological and ergo-
nomic comfort.
2
2 Methods und Discussion
2.1 Sensorial comfort characteristics
The sensorial comfort characteristics are mainly determined by the textile's surface structure, which can be
characterized by specific quantities.
If a fabric is clinging on moist skin, this is felt as uncomfortable by the wearer. The intensity of "wet cling"
on the skin can be expressed by a wet cling index iK. For measurements a special apparatus mainly consisting
of a sintered glass plate is used, which in its surface roughness equals human skin. The porous surface of the
sintered glass plate is moistened with distilled water. The force, which is necessary to draw the sample hori-
zontally across the sintered glass plate describes the wet cling index iK(6). The lower values, the less uncom-
fortable wet cling is felt. Particularly iK should be below 15.
Under heavy sweating a textile worn next to the skin is felt the more comfortable, the faster liquid sweat is
transported away from the skin. This sorption speed can be determined of a water drop of defined size falling
above the sample onto the fabric's inner surface. By measuring the contact angle of the water drop the time
lapse can be extrapolated, after which the water drop has been completely absorbed by the sample. This time
lapse yields the sorption index iB(7). About its sensorial comfort a fabric must be judged the better, the small-
er iB. Particularly iB should be below 270.
On one hand a textile is felt as too smooth on the skin on the other hand as too rough or scratchy. This
characteristic is given by the surface index io. Therefore, the number and length of the fiber ends protruding
from the fabric's bulk is measured(8). Regarding sensorial comfort a fabric must be judged as good if the sur-
face index io lies between 3 and 15.
A fabric is felt less sticky to the skin, the smaller its contact area with the skin. This contact area is mainly
determined by the fabric's surface structure, particularly by the distant keeping fiber ends protruding from the
fabric's bulk. Quantitatively a fabric's contact area with the skin can be expressed by the number of contact
points nK. This number is determined optically with a topograph, which gives a 3-dimensional picture of the
textile surface(9). A fabric is less sticky, the smaller the number of contact points nK. Particularly nK should
be below 1500.
The stiffness s of a fabric can be expressed by the bending angle against the perpendicular direction of a
fabric sample(10). The stiffness s describes, whether a fabric is felt as comfortable or as too flabby or too stiff.
By this definition s can assume values between 0 (completely flabby) and 90 (completely rigid). In order to
yield good sensorial comfort for sportswear fabrics s should lie between 5 and 27.
2.2 Thermophysiological comfort characteristics
Skin Model
The thermoregulatory model of human skin (Skin Model) simulates the dry as well as the sweating human
skin. With the Skin Model the specific thermophysiological quantities of textiles as layers, relevant to physio-
logical comfort, can be determined. So, the thermophysiological comfort can be characterized. Under “nor-
mal” or “stationary” conditions the moisture flux from the skin appears as water vapor (insensitive sweating).
In this stationary case the water vapor resistance Ret including short-time water vapor absorbency Fi can be
measured according ISO 11092(1). Further the thermal resistance (thermal insulation) Rct is determined under
these stationary conditions. In general upholstery systems more specifically their material combinations are
rated the better, the lower water vapor resistance Ret and higher the short-time water vapor absorbency Fi.
For the clothing physiological properties of textiles not only their stationary thermo-physiological proper-
ties are important but also the capacity to buffer sweat pulses which are occurring quite frequently in the prac-
tical use of textiles and clothing. Concerning the buffering capacity, it must be distinguished between two
mechanisms:
3
Buffering capacity of water vapor (moisture regulation index Fd): This measurement describes the wear
condition where the wearer is already sensibly sweating, but the sweat is still evaporating within the channels
of the skin's sweat glands. In the clothes' microclimate an increased water vapor pressure is occurring but still
no liquid sweat(2).
With the buffering capacity of liquid sweat (buffering index Kf) a wear condition is comprehended where
the wearer is sweating so heavily that there is liquid sweat on his skin(3).
Like the stationary wear conditions, also the instationary conditions can be simulated with the Skin Model.
A description of the test procedures is given in the Standard-Test Specification BPI 1.2(2, 3). Therefore, high-
er sweating rates while sitting during a long-term drive can be described by Fd- and Kf-value. Both thermo-
physiological characteristics must be rated better with higher values.
Fig. 1. Schematic structure of the sweating guarded hot plate (Skin Model).
Sweating buttocks
Measurements with the Sweating Buttocks Model (Institut für Holztechnologie Dresden gGmbH) or Seat
Test Automotive Manikin (Thermetrics) determine sweat management (moisture accumulation, moisture
transport, moisture degradation) of 3-dimensional cushion compositions following real conditions (Fig. 2).
Thus, a deeper understanding of the thermophysiological comfort of upholstery systems can be gained.
The Sweating Buttocks Model is placed on the sample with a load of 400 N, which simulates an adult
standard man. Further sweating while sitting can be simulated by the Sweating Buttocks Model. There are
combined temperature and moisture sensors built-in the measuring head of the Sweating Buttocks Model.
These sensors detect the temperature and moisture within the microclimate between Sweating Buttocks Model
and cover of the upholstery system. By adding combined temperature and humidity sensors into the material
combination of the upholstery system, additional information about the heat and moisture distribution can be
obtained.
During the measurement the initial heat flux Hci is detected. It represents the situation of a person sitting on
a cold or hot upholstery system compared to skin temperature. In the moment of contact the maximum heat
flux Hci max from the human body to the cold upholstery or from the hot upholster to the human body (negative
values) take place. For a good thermophysiological comfort the amount of Hci max should be less than 85 W/m².
So, there is no uncomfortable fleeing during the first contact with the upholstery and the upholstery is per-
ceived as hot or cold. A comfortable feeling results with Hci max < 64 W/m ². Further the time span for aligning
the skin temperature and the temperature of the upholstery should the short. Th initial initial heat flux Hci is
mainly influenced by the cover material of the material composition.
4
Fig. 2. Sweating Buttocks Model in climatic chamber (left), anatomically shaped measuring head on cushion composition
(right).
Thermal, sweating Manikin
For measurements of complete ready-made clothing systems or upholstery systems thermal, sweating mani-
kins were developed since 1980s. Thus, heat and moisture management of a human body can be simulated
while taking the shape of the human into regard. In comparison to the thermal, sweating body segments (e.g.
Sweating Buttocks) the manikins are highly variable in use.
The thermal resistance Rc and water vapor resistance Re measurements of ready-made systems can be per-
formed with thermal, sweating manikins. The thermal, sweating manikins Newton and Andy by Thermetrics
are the only commercially available sweating manikins (11). Newton is available with 20, 26, 34 or 35 inde-
pendent thermal and sweating segments. A skin-tight sweat suit distributes the water homogeneously over the
manikin’s surface. Newton has a wide range of body motions e.g. running, sitting, lying (Fig. 3).
In general, thermal resistance measurements Rc are carried out under non-isothermal conditions and water
vapor measurements Re under isothermal conditions. The measurement of water vapor resistance Re with a
thermal, sweating manikin is standardized in the ASTM F2370(12). Further an ISO standard is in process(13).
For calculating the thermal and water vapor resistance for more than one segment there are different calcula-
tion models available: the parallel, the serial and the global calculation model.[88] The results of the different
calculation models differ significantly for a given clothing system(14). In general, the standards contain an
indication which of these models is to be used for the specific application.
Fig. 3. Thermal, sweating Manikin Sherlock (Newton type, Thermetrics) in sitting position.
5
2.3 Ergonomic comfort characteristics
Pressure pad
Dealing with the comfort while sitting the ergonomic comfort is important, too. Therefore, the contact area
between human and seat as well as the pressure distribution on the seat should be investigated. The pressure
distribution of a sitting person can be qualified by measurements with a pressure pad. Fig. 4 shows for exam-
ple the pressure distribution of a sitting person on a car seat. Further this measurement provides information
about the contact area between human and upholstery system.
Fig. 4. Pressure distribution and contact surface of a human sitting on a car seat.
3D-Scanning
In fields like automotive it is common practice to analyse seating situations with 3D simulation software for
many years(15-17). These tools enable to simulate realistic positions of seat users with the aim to improve
safety, efficiency and comfort. Performing human-centered design is based on virtualized human bodies and
products. On the one hand digital human models are created by adapting existing manikins in regard of body
measurements via parameter setting. Similarly, products are developed and moulded in CAD software. On the
other hand, test persons or products are 3D scanned with full body or handheld scanner systems like Artec
Eva, Creaform Revscan and or low-cost devices as the Kinect sensor. The three-dimensional information of
seats, chairs or furniture can be compared with 3D data of target groups. Amongst other issues the following
points can be analyzed:
Is the seating surface long and wide enough?
Is the backrest high and wide enough?
How does the contact area look like in regard of size and shape?
Are adjustment handles ease to reach?
Are adjustments efficient?
Fig. 5. Comparing individual 3D body scan with office chair.
6
To perform these analysis, real person’s body scans give many advantages. The body forms are realistic.
Parametric models tend to look not like real human beings. Although simulation software improved enor-
mously, there are still problems with the visualization of the body surface due to movement. The research in
the field of scanning in motion (4D scanning) and capturing human bodies in different postures will lead
steadily to enhanced performance of simulation software(18-20). Furthermore, creating a data pool of full
body scans in different positions combined with socio-demographic questions allows to choose focused target
pool representatives (factory or office workers, specific age groups or BMI cluster etc.). Or, in a next step cal-
culate average manikins with not only average body measurements but as well average body geometry and
posture.
3 Conclusion
In conclusion it can be stated that the comfort while sitting is important. It is possible the characterise dif-
ferent aspects of upholstery systems.
The sensorial comfort describes mainly the textile surface structure of the face fabric by five specific quan-
tities: wet cling index iK, sorption index iB, surface index iO, number of contact points nK and stiffness s.
The thermophysiological comfort can be described by measurements with the thermoregulatory model of
the human skin Skin Model for short. It can simulate the human dry as well as the sweating skin. Under sta-
tionary measurements thermal resistance Rct and water vapour resistance Ret are determined. For the clothing
physiological properties of textiles next to the skin not only their stationary thermophysiological properties
are important but also the capacity to buffer sweat pulses which are occurring quite frequently in the practical
use of textiles and clothing. Concerning the buffering capacity, it must be distinguished between two mecha-
nisms: Buffering capacity of water vapour Fd and buffering capacity of liquid sweat Kf. A deeper understand-
ing of the thermophysiological comfort of upholstery systems can be gained by measurements with three di-
mensional systems such as the Sweating Buttocks Model or thermal, sweating manikins.
The ergonomic comfort can by characterized by pressure pads, which determine the contact area between
human and seat as well as the pressure distribution. Further the seating situations can be described with 3D
simulation software. These tools can simulate realistic positions of seat users with the aim to improve safety,
efficiency and comfort.
Acknowledgments IGF project 18080 BG and ZIM project KF2136735CJ4 were founded through the AiF within the frame-
work of the program for promotion of cooperative industrial research (IGF) by the German Federal Ministry for Economic Af-
fairs and Energy based on a resolution by the German Bundestag.
References
1. DIN. ISO 11092. Textilien - Physiologische Wirkungen - Messung des Wärme- und Wasserdampfdurchgangswiderstandes
unter stationären Bedingungen (sweating guarded-hotplate test). Berlin: Beuth Verlag GmbH; 2014.
2. Hohenstein Institut für Textilinnovation e.V. Bestimmung der Pufferwirkung von Textilien mit dem Thermoregulationsmodell
der menschlichen Haut (Hautmodell). Standard-Prüfvorschrift HIT 12: Hohensteiner Institute; 2000.
3. Hohenstein Institut für Textilinnovation e.V. Bestimmung der Pufferwirkung aus der flüssigen Phase von Textilien mit dem
Thermoregulationsmodell der menschlichen Haut (Hautmodell). Standard-Prüfvorschrift BPI 121: Hohensteiner Institute;
2010.
4. Hertzberg HTE. The Human Buttocks in Sitting: Pressure, Patterns, and Palliatives. Society of Automotive Engineers.
1972;72005.
5. Froböse I, Wallmann-Sperlich B. Der DKV-Report „Wie gesund lebt Deutschland?“. Zentrum für Gesundheit der deutschen
Sporthochschule Köln; 2015.
6. Prüfung von Textilien - Bestimmung des Klebeindex (wet clinging index) ik - Versuchsanordnung und
Versuchsdurchführung. Standard-Prüfvorschrift HIT 31: Hohenstein Institute; 2004.
7
7. Prüfung von Textilien - Bestimmung des Benetzungsindex (sorption index) iB - Versuchsanordnung und
Versuchsdurchführung. Standard-Prüfvorschrift HIT 32: Hohenstein Institute; 2004.
8. Prüfung von Textilien - Bestimmung des Oberflächenindex (surface index) iO - Versuchsanordnung und
Versuchsdurchführung Standard-Prüfvorschrift HIT 33: Hohenstein Institute; 2004.
9. Prüfung von Textilien - Bestimmung der Zahl der Kontaktpunkte zwischen Textil und Haut (number of contacts between
textile and skin) nK. Standard-Prüfvorschrift HIT 34: Hohenstein Institute; 2003.
10. Prüfung von Textilien - Ermittlung der Steifigkeit (stiffness) s - Versuchsanordnung und Versuchsdurchführung. Standard-
Prüfvorschrift HIT 35: Hohenstein Institute; 2003.
11. Thermetrics. Newton Thermal Manikin System http://www.thermetrics.com/products/full-body-manikins2019 [Available
from: http://www.thermetrics.com/products/full-body-manikins.
12. Standard test methoc for measuring the evaporative resistance of clothing using a heated manikin. ASTM F 2370-10.
Philadelphia2010.
13. Holmér I. Use of thermal manikins in international standards. In: Fan J, editor. Sixth International Thermal Manikin Aand
Modelling Meeting (6I3M); Hong Kong2006.
14. ISO. Ergonomics of the thermal environment - Estimation of thermal insulation and water vapour resistance of a clothing
ensemble. ISO 99202007.
15. Akamatsu M, Green P, Bengler K. Automotive Technology and Human Factors Research: Past, Present, and Future.
International Journal of Vehicular Technology. 2013;2013:27.
16. Duffy VG. Handbook of Digital Human Modeling. Boca Raton: CRC Press; 2008.
17. Gkikas N. Automotive Ergonomics. Boca Raton: CRC Press; 2013.
18. Heindl C, Bauer H, Ankerl M. ReconstructMe SDK: a C API for Real-time 3D Scanning. 6th International Conference on 3D
Body Scanning Technologies; Lugano (CH)2015.
19. Aguiar Ed. Performance Capture Methods. European Conference on Computer Vision (ECCV); Zürich2014.
20. Lane C. The Potential for Dense Dynamic 4D Surface Capture Illustrated with Actual Case Studies 4th International
Conference on 3D Body Scanning Technologies; Long Beach (USA)2013.
ResearchGate has not been able to resolve any citations for this publication.
Book
Full-text available
The 13th International Conference on Human–Computer Interaction, HCI International 2009, was held in San Diego, California, USA, July 19–24, 2009, jointly with the Symposium on Human Interface (Japan) 2009, the 8th International Conference on Engineering Psychology and Cognitive Ergonomics, the 5th International Conference on Universal Access in Human–Computer Interaction, the Third International Conference on Virtual and Mixed Reality, the Third International Conference on Internationalization, Design and Global Development, the Third International Conference on Online Communities and Social Computing, the 5th International Conference on Augmented Cognition, the Second International Conference on Digital Human Modeling, and the First International Conference on Human Centered Design. A total of 4,348 individuals from academia, research institutes, industry and governmental agencies from 73 countries submitted contributions, and 1,397 papers that were judged to be of high scientific quality were included in the program. These papers address the latest research and development efforts and highlight the human aspects of the design and use of computing systems. The papers accepted for presentation thoroughly cover the entire field of human–computer interaction, addressing major advances in knowledge and effective use of computers in a variety of application areas. This volume, edited by Vincent G. Duffy, contains papers in the thematic area of Digital Human Modeling, addressing the following major topics: • Face, Head and Body Modeling • Modeling Motion • Modeling Behavior, Emotion and Cognition • Human Modeling in Transport Applications • Human Modeling Applications in Health and Rehabilitation • Ergonomic and Industrial Applications • Advances in Digital Human Modeling
Article
Full-text available
This paper reviews the history of automotive technology development and human factors research, largely by decade, since the inception of the automobile. The human factors aspects were classified into primary driving task aspects (controls, displays, and visibility), driver workspace (seating and packaging, vibration, comfort, and climate), driver's condition (fatigue and impairment), crash injury, advanced driver-assistance systems, external communication access, and driving behavior. For each era, the paper describes the SAE and ISO standards developed, the major organizations and conferences established, the major news stories affecting vehicle safety, and the general social context. The paper ends with a discussion of what can be learned from this historical review and the major issues to be addressed. A major contribution of this paper is more than 180 references that represent the foundation of automotive human factors, which should be considered core knowledge and should be familiar to those in the profession.
Article
After a brief description of relevant buttock structure, the author presents summary data on buttock size, tuberosity locations, and other dimensions needed for improved seat design, as measured from a sample of 35 young males chosen to approximate the range of USAF flying personnel. Summary load patterns for two angles of seat back are shown, and suggestions to reduce the discomfort of long-continued sitting are made. Curves and data for successful USAF seat surfaces are presented. Citing recent increases in American body size, the author calls for an anthropometric survey on a national sample in which numerous data needed for automotive and other industrial design would be acquired. (Author)
Wie gesund lebt Deutschland?". Zentrum für Gesundheit der deutschen Sporthochschule Köln
  • I Froböse
  • B Wallmann-Sperlich
  • Der Dkv-Report
Froböse I, Wallmann-Sperlich B. Der DKV-Report "Wie gesund lebt Deutschland?". Zentrum für Gesundheit der deutschen Sporthochschule Köln; 2015.
Thermal Manikin System
  • Thermetrics
  • Newton
Thermetrics. Newton Thermal Manikin System http://www.thermetrics.com/products/full-body-manikins2019 [Available from: http://www.thermetrics.com/products/full-body-manikins.
Use of thermal manikins in international standards
  • I Holmér
Holmér I. Use of thermal manikins in international standards. In: Fan J, editor. Sixth International Thermal Manikin Aand Modelling Meeting (6I3M);
Ergonomics of the thermal environment -Estimation of thermal insulation and water vapour resistance of a clothing ensemble
  • Iso
ISO. Ergonomics of the thermal environment -Estimation of thermal insulation and water vapour resistance of a clothing ensemble. ISO 99202007.
The Potential for Dense Dynamic 4D Surface Capture Illustrated with Actual Case Studies 4th International Conference on 3D Body Scanning Technologies
  • C Lane
Lane C. The Potential for Dense Dynamic 4D Surface Capture Illustrated with Actual Case Studies 4th International Conference on 3D Body Scanning Technologies; Long Beach (USA)2013.