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Abstract and Figures

This study involves evaluation of the suitability of ergonomic criteria for seat models grouped under two different types (light and medium) in various armchair designs. Survey and contact surface pressure distribution measurement methods were utilized to conduct the evaluation. A total of 4 different seat models were investigated in order to compare the survey data with the data obtained from the mat (surface pressure distribution meter). Five out of ten criteria for evaluation and classification of the seat models were used in the study. (i) lightweight and 2 medium-type seat model; (ii) lumbar support, (iii) back support, (iv) armrest height, (v) is anthropometric. The participants of the study comprised of 30 subjects (15 females and 15 males) who self-reported to have no serious health conditions and were voluntarily tested on the seats for two intervals: 5 and 30 minutes. Subjects were assessed by the same surveys and the qualitative ratings of comfort that their bodies felt in various areas. It was analyzed whether the percentages of comfort obtained from the surveys were consistent with the mat results by taking quantitative (numerical) data from the sitting surface using mat. Consistency of results obtained from survey and pressure mat measurements were performed as well. Both ergonomic assessment techniques did point out same armchair designs as the best and worst. Based on these results, solution proposals for ergonomic armchair design were presented.
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4th International Furniture and Decoration Congress, Duzce,Turkey
(4.Uluslararası Mobilya ve Dekorasyon Kongresi)
484
TEKLİ KOLTUKLARIN ERGONOMİK KRİTERLER VE KONFOR
BAKIMINDAN İNCELENMESİ
Mehmet YÜKSEL1, Ali KASAL1
L
1
, Yusuf Ziya ERDİL1, Halil KILIÇ1, Can ÖZCAN2
ya
¹Muğla Sıtkı Koçman University, Faculty of Technology, Department of Woodworking
Industrial Engineering, 48000 Kötekli/MUĞLA
2Akro Mühendislik, GOSB Teknopark – Kemal Nehrazoğlu Cad. High Tech Bina, Kocaeli,
Türkiye myuksel@mu.edu.tr
Bu çalışma, çeşitli tasarımlardaki iki farklı tip (hafif ve orta tip) altında
Bu
Özet:
gruplandırılmış koltuk modellerinin ergonomik kriterlere uygunluğunun
değerlendirilmesini içermektedir. Değerlendirme anket ve temas yüzeylerinde basınç
dağılımı ölçümü yöntemleri kullanılarak gerçekleştirilmiştir. Anket verilerinin, mat (yüzey
basınç dağılım ölçer) dan elde edilen verilerle kıyaslanabilmesi için toplam 4 farklı koltuk
modeli incelenmiştir. Çalışmada kullanılan koltuk modellerinin değerlendirilerek
sınıflandırılmasında kullanılan 10 kritereden 5 kriter ön plana çıkmıştır: (i) hafif ve orta
tipte koltuk modeli; (ii) lumbar desteği olan ve lumbar desteği olmayan, (iii) arkalık desteği
yarım ve tam olan, (iv) kolçak yüksekliği uygun olan ve olmayan, (v) antropometrik
ölçülere uygun olan ve olmayan. Çalışmaya gönüllülük esasına göre katılan 30 sağlıklı
denek (15 kadın ve 15 erkek) 30 dakika deney koltuklarında oturmuştur. Deneklere 2 farklı
zaman noktasında (5. ve 30. dakika) aynı anket uygulanarak vücutlarının çeşitli
bölgelerinde hissettikleri rahatlık dereceleri niteliksel (kalitatif) olarak tespit edilmiştir.
Ayrıca mat kullanılarak oturma yüzeyinden kantitatif (sayısal) veriler alınarak anketlerden
elde edilen rahatlık yüzdelerinin, mat sonuçları ile tutarlı olup olmadığı kıyaslanmıştır.
Sonuç olarak, matdan alınan verilerin rahatlık düzeyi ile, anketlerden alınan verilerin
rahatlık düzeyleri arasındaki ilişkinin tutarlı olduğu belirlenmiş olup, koltuk tasarımına
ilişkin çeşitli çözüm önerileri sunulmuştur.
ilişki
Anahtar kelime: Ergonomi, Tekli koltuk, Konfor, Antropometri, Mat (Pressure map),
Ergonomi.
STUDY ON SINGLE SEAT ARMCAHIRS IN TERMS OF
ERGONOMICS AND COMFORT
This study involves evaluation of the suitability of ergonomic criteria for seat
Th
Abstract:
models grouped under two different types (light and medium) in various armchair designs.
Survey and contact surface pressure distribution measurement methods were utilized to
conduct the evaluation. A total of 4 different seat models were investigated in order to
compare the survey data with the data obtained from the mat (surface pressure distribution
Mehmet YÜKSEL, Ali KASAL
, Yusuf Ziya ERDİL, Halil KILIÇ, Can ÖZCAN
485
meter). Five out of ten criteria for evaluation and classification of the seat models were
used in the study. (i) lightweight and medium-type seat model; (ii) lumbar support, (iii)
back support, (iv) armrest height, (v) is anthropometric. The participants of the study
comprised of 30 subjects (15 females and 15 males) who self-reported to have no serious
health conditions and were voluntarily tested on the seats for two intervals: 5 and 30
minutes. Subjects were assessed by the same surveys and the qualitative ratings of comfort
that their bodies felt in various areas. It was analyzed whether the percentages of comfort
obtained from the surveys were consistent with the mat results by taking quantitative
(numerical) data from the sitting surface using mat. Consistency of results obtained from
survey and pressure mat measurements were performed as well. Both ergonomic
assessment techniques did point out same armchair designs as the best and worst. Based on
these results, solution proposals for ergonomic armchair design were presented.
thes
Key words: Ergonomics, single seater armchair, comfort, anthropometrics, pressure mat.
1. INTRODUCTION (GİRİŞ)
The human beings who lived in prehistoric times were hunting in the daytime to survive, and they
continued their lives in the cave, tree hut or rock hut to be protected from wild animals and bad
weather at night. Over time, they learned to meet the need for food and shelter by means of
agriculture and sewing. They used stones, trees, etc. to create living areas and things to sit on.
Since it is not possible for a person to learn everything and meet all his needs all by himself, it was
vital to live collectively. People started to live collectively: after they built houses, they started to
work in various professions. Thus, they started to buy bread from the bakery, vegetables and fruit
from the grocery store, and furniture from the furniture manufacturer. Over time, the development
of the industry helped to shape the business life and allowed people to continue their lives by
working at work. It is important for the seating element; to support the areas where the body
touches the seating element, to match the dimension between the human-sitting elements, to be
ergonomic, to sit comfortably, and to provide relaxation. This is the work of ergonomists, and in the
furniture sector, work on more comfortable furniture production has increased in recent years
thanks to ergonomics scientists. Today, technology has developed and various studies have been
carried out to increase the comfort of seating elements. At home or at work, people feel the need for
a comfortable sitting during daytime or in the evenings. It is a necessity to increase the comfort for
easing the sitting related problems in seating elements.
Smardzewski, J. (2013) studied on Auxetic springs for seating, auxetic springs for seating tested
and determine their resistance to cyclic as well as prolonged static loads. The results of his
investigations made it possible to conclude that the designed spring had stiffness characteristics
similar to the compression characteristics of polyurethane foams, cyclical and prolonged static loads
had no significant influence on changes in spring height so their impact on the comfort of seating
was insignificant on the setting [1].
Smardzewski, J. at al. (2014) studied the structure and properties of composite seat with auxetic
springs. The performed laboratory tests corroborated the obtained calculation results and
demonstrated that the impact of seat modification with the NHE35 foam was negligible. The
examined seats exhibited comparable stiffness and comfort of utilization. Numerical modelling can
Mehmet YÜKSEL, Ali KASAL
, Yusuf Ziya ERDİL, Halil KILIÇ, Can ÖZCAN
486
constitute a useful tool for rapid prototyping of complex, multilayer systems made up of materials
with non-linear characteristics [2].
In another study, Smardzewski, J. at al. (2014) stated that contact stresses between the seat cushion
and the user’s body should decrease as a result of application of a frictionless combination of thin
layers of polyurethane foams with foams forming the proper elastic layer of the seat. It was also
suggested that seat cushion stiffness assessment should be carried out using the identical loading
pads of stiffness selected by the investigator [3].
Smardzewski, J. (2019) studied on antropotechnical aspects of furniture design, when designing
furniture for sitting at tables. The aim of the research project was to present anthropotechnical
aspects of furniture design for sitting and meal consumption. He discussed the methodology of the
assessment of ergonomics of a chair, a table and a chair + table set, where the assessment criteria
were: anthropometric dimensions of the user, stiffness of seats and the value of contact strains on
the seat surface. It is necessary not only to take care of correct chair dimensions but also to select
appropriate dimension relationships between these two pieces of furniture [4].
Smardzewski, J. (2013) studied the evaluation of seat comfort of office armchairs, precisely an
impact of articulated seat support and gas spring. The goal of this alternative approach was to
determine the comfort of office armchairs equipped with new construction solutions ensuring
articulated support of the seat as well as articulated mounting of the gas spring. He indicated that
the new construction solution of the gas spring support guaranteed the highest comfort of the use of
the examined armchairs [5].
Ahmadian, M., (2004) carried out a field study to evaluate driver fatigue
on air-inflated truck seat cushions. He conducted a series of road tests in regular fleet operations of
a revenue service to better understand the relationship between vehicle seat design and driver
fatigue, improve two newly proposed objective methods for evaluating driver fatigue, and provide
design guidelines for evaluating and improving vehicle seat characteristics in
terms of driver fatigue. Results indicated that the air-inflated seat cushion had advantages in terms
of subjective measures of comfort, support, and fatigue. In addition, the results highlight the
advantages of using these measures to evaluate the fatigue performance of distinct types of seat
cushions namely foam and air-inflated seat cushions [6].
Smardzewski, J. (2012) studied models of hybrid springs for ergonomic seats and mattresses.
He aimed at developing a new construction of an upholstery spring of bilinear stiffness. On the
basis of the conducted studies and analysis of their results, this study showed that traditional bonnell
and barrel springs exhibited linear stiffness within the range of deflections of up to 70 % of their
initial pitch. New spring designs changed stiffness already at deflections of 34% of their pitch. They
may be used in designs of seats and mattresses for individual users [7].
Altiparmakogullari Y., (2009) attemted to develop criteria for the seating profile by using pressure
diagram model for designing seating units. The purpose of this study was to show the importance of
customized seating units which are designed
considering the physiological and anthropometric features of individuals. In order to
actualize the purpose of the study, an experiment was conducted with 13 university
students whose body-mass index was fixed. Moreover, the effects of different postures, seating
heights, support situations and seating slopes on pressure were examined. Findings of the
experiment showed that seating contrivances which were prepared regarding average values and
Mehmet YÜKSEL, Ali KASAL
, Yusuf Ziya ERDİL, Halil KILIÇ, Can ÖZCAN
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disregarding the anthropometric features of individuals did not provide seating comfort. The
variables of seating unit affected seating comfort and several physiological problems. Thus, the
significance of designing customized seating units according to the physiological and
anthropometric features of individuals could be seen clearly. Finally, customer design was very
important for comfort [8].
The purpose of this study was to determine the comfort of 4 different types of
armchairs by using pressure mat values and survey data. In these armchairs, correlations among
lumbar support, seating height, seating depth, and backrest factors which are the most influential
factors on comfort of the armchairs were analyzed.
2.MATERIAL AND METHOD (MATERYAL VE METOD)
This study involved evaluation of the ergonomic suitability of armchairs by using both survey and
pressure mat. The study consisted of 4 different ergonomics characteristic armchairs that were
obtained from a manufacturer. Subjects were 30 volunteers (15 females, 15 males aged 19-31 years
old) who self-reported to have no serious health conditions. Armchair sample and dimensions are
shown in Figure 1 and Table 1.
Model 1
Model 2
Model 3
Model 4
Figure 1. The armchair models used in this study (Çalışmada kullanılan koltuk modelleri)
Table 1. Dimensions and properties of the armchair used in this study (Bu çalışmada kullanılan
koltuk boyutları ve özellikleri).
Pressure mat was placed on the surface of the armchair to obtain values of the pressure distribution.
3D and 2D pressure distribution view is shown in Figure 2.
Armchair Dimensions
Armchair Model Number
1
2
3
4
Seat width (cm)
47
46
54
59
Seat depth (cm)
44
49
52
59
Seat hight (cm)
45
42
41
45
Back rest angle ( o)
103
102
103
101
Arm rest hight (cm)
21,5
16
19
20,5
Lumbar support
Half support
Half support
Full support
No support
Backrest hight (cm)
82
81
92
90
Mehmet YÜKSEL, Ali KASAL
, Yusuf Ziya ERDİL, Halil KILIÇ, Can ÖZCAN
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a. A pressure mat on the
surface of armchair
b. 3D Pressure distribution
view
c. 2DPressure distribution view
Figure 2. The pressure mat 3D and 2D recorded views (basınç matı ve kaydedilmiş 3D ve 2D
görüntüler)
In the first part of study, primarily, 60 different static anthropometric dimensions and circular
measurements were obtained from 30 participants using anthropometric measuring sets. These data
were then used to make comparisons between armchair and human dimensions. Armchair sample is
shown in Figure 3.
Figure 3. The isometric view a subject that is sitting on an armchair sample used in this study (Bu
çalışmada kullanılan koltuk örneğinde oturan bir deneğin izometrik görüntüsü)
2.1. Evaluation of Surveys (Anketlerin değerlendirilmesi)
Surveys were conducted with 30 subjects. Total survey included 240 items: 30 subjects (15 females
and 15 males), 4 different types of seat models (30 subjects X4 model armchair X 2 sitting time
intervals = 240 questionnaires). Time intervals were 5 and 30 minute time intervals. Subjects were
seated and surveyed one at a time. In other words, more than one questionnaire was not
administered on the same day to obtain reliable data. The level of comfort of the subjects was
measured from their perceptive-- feeling after the seating action. The subjects were allowed to sit
for the prescribed time (5 and 30 minutes) and the feelings about 10 different body areas of the
subjects' bodies were surveyed by 5-point Likert scale questionnaire. In order to obtain 100 points,
Mehmet YÜKSEL, Ali KASAL
, Yusuf Ziya ERDİL, Halil KILIÇ, Can ÖZCAN
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ratings between 2 and 10 points was made for each scale from very uncomfortable (2) to very
comfortable (10) (Figure 4).
The five-points Likert-scale questionnaire scored 100 points out of 10 different questions (10 x 10 =
100) for 10 different regions. The score distribution was as follows:
Very Uncomfortable: 2 Points
Uncomfortable : 4 Points
Medium :6 points
Comfort :8 points
Very Comfort :10 points
The largest score (10 x 10 = 100) in the Likert scale was accepted as 100 points. Comfort level
determination questionnaire set is given in Figure 4.
Body
regions
Ve
ry
Uncomforta
Uncomforta
ble
Medium
Comfort
Very
Comfortabl
Neck
Shoulders
Back
Lumbar
area
Hip
Thigh
Arms
Legs
Feet
General
stance
Figure 4. The questionnaire sample for determining the comfort level (Konfor seviyesinin
belirlenmesine yönelik anket örneği) [9,10].
2.2. Evaluation of Pressure mat (Basınç matının değerlendirilmesi)
Pressure distributions at the body’s interface with the seat surface was captured using the pressure
mat. Sensor mat (sensing area 320 mm x 320 mm, poly thickness 2.5 mm, sensor size 16 mm,
sensor gap 4 mm, sensor arrangement 32 x 32, cover size 440 mm x 410 mm, number of sensors
256) was placed on the armchair surface. The mat was first calibrated and then connected to the
computer. After subjects sat for 60 seconds on the chair, direct measurement results were recorded
in a text file and presented graphically as distribution maps of contact pressure to use in the
statistical analyses. Pressure mat is shown in Figure 5.
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Figure 5. The mat which was placed on the furniture (Mobilya üzerine yerleştirilen basınç matı)
Indirect experimental results were collated in the form of diagrams comparing the following values:
A (m2) - contact area, pm (kPa) - average contact pressure, SPD (%) - coeffi cient [2,11].
(1)
where:
n number of sensors in which contact pressure has non-zero values,
pi contact pressure in any mat sensor,
pm average contact pressure for n sensors.
Since the comfort of sitting depends directly on the contact area, values of contact pressure as well
as on the above-mentioned SPD coefficient, a decision was also made to define and calculate the
value of the discomfort coefficient D (daN/m4) determined on the basis of the following formula:
[2].
(2)
In the case of a uniform contact stress distribution of the seat surface, pi pressure in any sensor
should be equal to the mean pressure pm. In such situation, the SPD coefficient should equal zero.
Therefore, seats with low SPD coefficient values can indicate a more uniform support of the user’s
body in comparison with seats characterized by high SPD. This, however, does not rule out the
situation in which the developing stress will be too high for sitting comfort. In the case of the D
coefficient, it should be expected that a high user’s discomfort will be obtained at high pm and SPD
and small A surface. In this situation, low values of the D coefficient will weigh in favor of high
comfort of seat utilization [2].
Also distribution of pressure were recorded by sitting on the test samples during the 60 seconds in
the each type of armchair shown in Figure 3. Especially, the relation of the single seats with the
human being examined and analyzed in terms of ergonomics criteria and the suitability investigated
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in terms of comfort. That, voluntary 30 subjects were tested by sitting on the test samples, sitting
posture shown in Figure 4. During the sitting time in each type of armchairs, the same survey was
applied on 2 different time intervals (5th and 30th minutes), thus, the comfort level subjects felt on
various parts of their bodies were tested qualitatively. After that, level of comfort that related to
different seat height, seat depth, backrest height, backrest and relations among these factors were
analyzed.
Distribution of pressure was recorded by sitting time on the test samples during the 60 seconds in
the each type of armchair for the pressure distribution values. Formula 1 was used to obtain the SPD
(Seat pressure distribution) values, then formula 2 was used to determine D (Mat-distribution)
values for comfort.
3.FINDINGS (BULGULAR)
3.1 Evaluation of Female Subject Data (Kadın Denek Verilerinin Değerlendirilmesi)
ANOVA results indicated that the level of comfort of the subjects was statistically different at the
5% significance level (Table 2).
The least significant difference (LSD) multiple comparison procedure at 5% significance level was
performed to determine the mean differences of the level of comfort the subjects felt percentile,
while seating on the armchairs the ANOVA results mentioned for female subjects.
Table 2. Summary of ANOVA results for comfort percent value of the female subjects (Kadın
deneklerin konfor yüzdesi değerleri için ANOVA sonuçlarının özeti)
Source
Degrees of
Freedom
Sum of squares
Mean Square
F Value
P Value
A
3
4820.344
1606.781
7.3079
0.0002
B
1
1046.531
1046.531
4.7598
0.0311
Error
120
26384.250
219.869
Total
127
32355.219
Average comfort values of the female subjects that were sitting in the armchairs are presented in
Table 2.
Table 3. Performance of seating comfort on four different armchair model for female subject
(Kadınlara yönelik dört farklı koltuk modelinde oturma konforunun performansı)
Armchair Model
X
HG
Model 3
76.25
A
Model 4
70.63
AB
Model 1
65.88
BC
Model 2
59.56
C
LSD value= 7.340 X: Value average HG: Homogeneous group
Test results showed that armchairs models were significantly affected in terms of armchair models.
3th model armchair showed the highest values (76.25 ). The lowest uncomfortable armchair were
obtained from 2nd model armchair sample (59.56 ) for the 7.340 LSD values. According to Table 3,
comfort level indicated that 3th model armchair had %28 more comfort than 2nd model armchair.
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Table 4. Effect of sitting time (time interval) on the comfort for female subjects (Oturma süresinin
(zaman aralığı) kadınlar için konfora etkisi)
Time interval
X
HG
5. min.
70.94
A
30. min
65.22
B
LSD value= 5.190 X: Value average HG: Homogeneous group
Table 4 indicates that relationship between seating time intervals of the comfort level for female
subjects. The single LSD values of 10.38 on the comfort for female subject tests were calculated
based on the error mean square of the full model. Results indicated that the 5 min (70.94) comfort
was better than 30 min. According to Table 4, comfort level obtained that 5 seating time point had
% 8 more comfort than 30 seating time interval
Table 5. Mean comparisons of comfort values between armchair models and seating time intervals,
for the female subjects (Kadınlar için koltuk çeşitleri ve oturma zaman noktaları arasındaki konfor
yüzdelik değerlerinin ortalamalarının karşılaştırmaları)
Armchair Models +Seating Time Intervals
X
HG
3. model + 5. min.
78.38
A
3. model + 30. min.
74.13
A
4. model + 5. min.
72.63
AB
1. model + 5. min.
70.13
ABC
4. model + 30. min.
68.63
ABC
2. model +5. min.
62.63
BCD
1. model + 30. min.
61.63
CD
2. model + 30. min.
56.50
D
LSD value= 10.38 X: Value average HG: Homogeneous group
Average comparisons of comfort percent values between 3th model armchair with 5 and 30 min.
seating time intervals, for the female subjects are given in Table 5. Mean comparison results
indicate that 3th model armchair, with 5 and 30 min. seating time intervals (78.38, 74.13) showed
the highest comfort values. But 2nd model of armchair with 30 min. seating time interval (56.50)
showed the lowest comfort values than all of test samples for the 10.38 LSD values. According to
Table 5, the 3th model armchair is the best comfortable armchair for female in both of the seating
time intervals. Female subjects were 39% more comfortable to sit on the 3th model armchair for 5
and 30 minutes time intervals than for the 2nd model armchair for 5 min. time interval.
3.2 Evaluation of Male Subject Data (Erker Denek Verilerinin Değerlendirilmesi)
ANOVA results indicated that the effect of all factors were statistically significant at 5%. The
analyses of variances are given in Table 6. The least significant difference (LSD) multiple
comparison procedure at 5% significance level was performed to determine the mean differences of
the level of comfort values.
Table 6. Summary of ANOVA results for comfort value of the male subjects (Erkek deneklerin
konfor yüzdesi değerleri için ANOVA sonuçlarının özeti)
Source
Degrees of Freedom
Sum of squares
Mean Square
F Value
P Value
A
3
8356.250
2785.417
28.2927
0.0000
Mehmet YÜKSEL, Ali KASAL
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B
1
3003.125
3003.125
30.5041
0.0000
Error
120
11814.000
98.450
Total
127
23259.500
Table 7 Shows the average comfort values of the male subjects that sitting in the armchairs
Table 7. Performance of seating comfort on 4 different armchair models for male subjects (Erkek
denekller için 4 farklı koltuk modelindeki oturma konforunun performansı)
Armchair Model
X
HG
Model 3
74.31
A
Model 1
61.50
B
Model 4
59.63
B
Model 2
51.81
C
LSD value= 4.911 X: Value average HG: Homogeneous group
According to the results, armchair models were significantly different in terms of armchair models.
The highest values were taken from than 3rd model armchair sample (74.31) and the lowest
uncomfortable armchair values were taken from than 2nd model armchair sample (51.81 ) for the
4.911 LSD values. , Comfort level indicated that armchair model 3 had %43 more comfort than 2nd
model armchair comfort levels of model 1 (61.50) and than 4th model armchair (59.63) were in the
middle: they were lower than 3rd model armchair and higher than 2nd model armchair (Table 7).
Table 8 shows the relationship between seating time interval of the comfort level for male subjects.
Table 8. Effect of seating time (time interval) on the comfort for male subjects (Oturma saatinin
(zaman araalığı) erkek denekler için konfor üzerindeki etkisi)
Time point
X
HG
5. min.
66.66
A
30. min
56.97
B
LSD value= 3.473 X: Value average HG: Homogeneous group
The single LSD value was 3.473 according to the results on the comfort for male subjects; tests
were calculated based on the error mean square of the full model. Results of analyze indicated, that
the 5 min. comfort was better than 30 min. seating time interval. The highest values of comfort
levels were taken from 5 min. time interval (66.66), and the lowest values were taken from 30 min.
time interval (56.97). According to Table 8, comfort level obtained with 5 min. seating time point
had %17 more comfort than 30 min seating time interval.
The data obtained from the survey were evaluated as a percentage, and the values of the pressure
distribution obtained from MAT were compared to the graphical expression of the D values
obtained using formula 2. Readability of the graphs is ensured with the highest absolute values in
the Figure 6 and 7.
The relationship between the survey and the pressure distributions of the comfort levels of the
experimental samples on female subjects is given in Figure 6.
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Figure 6. Comfort level between survey and pressure distribution for female subjects (Kadın
denekler için anket ve basınç dağılımı arasındaki konfor seviyesi)
The relationship between the survey and the pressure distributions of the comfort levels of the
experimental samples on male subjects is given in Figure 7.
Figure 7. Comfort level between survey and pressure distribution for male subjects (Erkek denekler
için anket ve basınç dağılımı arasındaki konfor seviyesi)
Figure 6 and 7 show the results of the survey and pressure mat. The highest comfort levels are both
of survey and pressure mat in Seat Model 3rd. The lowest comfort levels are both of survey and
pressure mat in Seat Model 2 nd. The results of the pressure distribution and the survey values match
for both female and male subjects. General comfort levels of armchair models were similar in this
study for all subjects.
4.CONCLUSIONS AND DISCUSSION (SONUÇ VE TARTIŞMA)
In this study, the effects of armchair design on comfort were investigated. The purpose was to
highlight design features which result in increased ergonomics and comfort. Two alternative
methods were employed to understand effects of design features on ergonomics. First, a survey
questioning the subjects comfort level at 5 and 30 min. seating time intervals were held. In parallel,
a pressure mat was placed on subject-armchair interface at thigh region to capture surface pressure
0
0,2
0,4
0,6
0,8
1
1,2
SEAT MODEL1
SEAT MODEL2
SEAT MODEL3
SEAT MODEL 4
FEMALE SUBJECTS
NORMALıZED D- GH VALUES SHOW COMFORTABLE SEAT
0
2
SEAT MODEL 1SEAT MODEL 2SEAT MODEL 3SEAT MODEL 4
MALE SUBJECTS
NORMALIZED D - HIGH VALUES INDICATE
COMFORTABLE SEAT
Mehmet YÜKSEL, Ali KASAL
, Yusuf Ziya ERDİL, Halil KILIÇ, Can ÖZCAN
495
distribution during seating. Each subject was seated to 4 armchairs with alternative design features
to collect data.
Both survey and pressure mat measurements showed that -3rd model armchair had higher comfort
scores, irrespective of subjects’ gender. Survey data shows that with increasing seating time, the
comfort scores decrease. This can be attributed to muscle fatigue under constant seating loads. The
most comfortable armchair type (3rd model armchair) did not change between 5 minutes and 30
min. seating time interval results. One may speculate that only 5 minutes seating time is adequate to
assess comfort levels of armchairs. But this decision should be based on the intended use of the
armchair: in other words the expected average seat time that the armchair is designed for.
3rd model armchair design had not only full lumbar and back support but also seat height and depth
dimensions which were well-suited to the subject group. With supporting design features the
subjects weight carried by the armchairs structure and muscular activity is minimized, thus
decreasing muscular fatigue levels. This outcome suggests that comfort can be explained by
biomechanic analysis of the subject. In the long run, we plan to include such muscular-skeletal
analysis for armchair comfort analysis using computer aided engineering software (e.g. AnyBody
Modelling System).
2nd model armchair model armchair was scored lowest in comfort survey, both for female and male
subjects. The lowest comfort scores for 2nd model armchair was given by male subjects. This can be
explained by design features of 2nd model armchair, where lumbar and backrest supports do not
cover the whole body but at most 50% of male’s possible contact area. Also the overall dimensions
of 2nd model armchair are smaller than of the other armchair models. Female subjects also
mentioned specific problems of missupport by the backrest with 2nd model armchair and reported
muscle fatigue at 30 min. seating time interval. Similar to 3rd model armchair results, comfort levels
generally decreased considerably, comfort level between 5 and 30 minutes was getting lower in
time, especially for female subjects.
It was also observed during seat tests that anthropometrics of men and women result in different
intermediate comfort outcomes. For large dimensionsed armchairs some women were not able to
make full ground support contact. Similary for small dimensioned armchairs most men were not
able to get enough support on seating surface, armrest, and back regions. These observations were
supported by increased contact pressure measurements, pressure mat as well. In order to achieve
full correlation between survey results and pressure mat measurements, all contact surfaces should
be included in the pressure mat measurements.
Next phases of this study is planned to include increased area/number of pressure mat
measurements and using the data for biomechanical analysis to support numerical comfort
assessments.
5.REFERENCES (KAYNAKLAR)
[1]. Smardzewski, J. (2013), “Auxetic springs for seating”, Turkish Journal of Agriculture
and Forestry, 37, pp 369-376.
[2]. Smardzewski, J. Jasinska, D., Janus-Michalska, M., (2014), “Structure And Properties
Of Composite Seat With Auxetic Springs”, Composite Structures, 113, PP 354-361.
[3]. Smardzewski, J., Prekrat, S., Pervan, S. (2014), “Research of Contact Stresses between
Seat Cushion and Human Body”, Drvna Industrıja 61 (2) pp. 95-101
Mehmet YÜKSEL, Ali KASAL
, Yusuf Ziya ERDİL, Halil KILIÇ, Can ÖZCAN
496
[4]. Smardzewski, J. (2019), Antropotechnical Aspects of Furniture Design, Drvna
Industrija, 60 (1) pp.15-21
[5]. Smardzewski, J. (2014), Wilk D., Pirog, A., Evaluation Of Seat Comfort Of Office
Armchairs: An Impact Of Articulated Seat Support And Gas Springthe, Drvna Industrija,
pp.183-189
[6]. Ahmadian, M., (2004), Field Study To Evaluate Driver Fatigue On Air-Inflated Truck
Seat Cushions, Master of Science Thesis, Faculty of the Virginia Polytechnic Institute and
State University, Blacksburg, Virginia.
[7]. Smardzewski, J. (2013), Studied On Models Of Hybrid Springs For Ergonomic Seats
And Mattresses, Drvna Industrija 64 (1) 9-18.
[8]. Altiparmakoğullari Y., (2009), Determining The Design Criterias Of Seating Profile By
Using Pressure Diagrame Model For Designing Seating Units, Master of Science Thesis
[9]. Kasal, Ö., Yıldırım K., (2004), Çizim mekanlarında insan-eylem-donatı elemanı
ilişkileri üzerine bir araştırma, Yüksek Lisans Tezi, Gazi Üniversitesi, Teknik Eğitim
Fakültesi, Dekorasyon Eğitimi Anabilim Dalı.
[10]. Kurban, H., ……….(2016)
[11]. Ahmadian, M.; Seigler, T. M.; Clapper, D.; Sprouse, A., (2002), Alternative test
methods for long term dynamic effects of vehicle seats. Paper presented at the meeting
SAE Truck and Bus Symposium, Detroit MI.
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Determining The Design Criterias Of Seating Profile By Using Pressure Diagrame Model For Designing Seating Units
  • Y Altiparmakoğullari
Altiparmakoğullari Y., (2009), Determining The Design Criterias Of Seating Profile By Using Pressure Diagrame Model For Designing Seating Units, Master of Science Thesis