Methods

This study was undertaken to design, develop, and evaluate the design of a new biocomposite chair to be used by students of polytechnics in Malaysia. The new- virtual prototype biocomposite chair with inputs from AD was tested and verified with input from AD analysis. Pugh’s total design process model was utilized for the design and development of the biocomposite chair with inputs from AD. This study was conducted with the intention to design, develop, evaluate, and virtually test with inputs from AD a prototype biocomposite chair used by polytechnic students. This study involves evaluation of AD of chair used by polytechnic students, conceptual design (generation), design, development, and evaluation of the chosen design of a new biocomposite chair. Therefore, this study was undertaken as per Figure 7.1.

Results and Discussion

This study utilized a modified version of the Pugh design model w'here the process starts with the evaluation of AD of chairs used by polytechnic students. The Pugh total design method is utilized w'here the product design specifications (PDSs) set out for the design of the new biocomposite chair. Next the conceptual design (generation using brainstorming, mind mapping, and morphological chart) of the chair and the evaluation of the design with input from AD are carried out with the weighted objectives method.

The ability and capability of humans to design a product must be adapted to human features. When there is a mismatch between a product and human features, automatically the feeling of discomfort will arise in users of the product. Therefore, all products must be manufactured according to users’ AD. Comfort assessment can be evaluated objectively and subjectively. Objective evaluation was carried out based on the existing parameters of the biocomposite polytechnic chair (Deros, Hassan, Daruis, & Tamrin., 2015).

In order to design the furniture for students, the 5th and 95th percentile values of the anthropometry dimensions were selected. Due to that, anthropometry dimensions obtained in this research study are important in order to provide the best design for Malaysian students. One of the most important aspects of this design is that the chairs must provide a good learning environment to the students. The biocomposite

Selected research area in the product development process

FIGURE 7.1 Selected research area in the product development process.

polytechnic chair can be designed to create comfort and satisfaction in the learning environment (Dawal et al., 2015).

Anthropometric Data Analysis

The collected AD was analyzed based on MS ISO 15535:2008 standard (SIRIM, 2008) and using SPSS program. The MS ISO standard method was used in order to check for irregular and outlier AD. The statistical data performed includes descriptive statistics (mean value, standard deviation, minimum, maximum, and 5th and 95th percentile) (Klamklay, Sungkhapong, Yodpijit, & Patterson, 2008) with the current findings of the study carried out using bivariate independent t-test analysis. Collected data was divided into several categories to facilitate analysis such as male student data, female student data, and overall data. Anthropometric measurements for each respondent were compared to the dimensions of furniture to identify the match or mismatch between the two.

Anthropometric Data Evaluation of Malaysian Adults

A total of 500 students, 213 males and 287 females, were involved in the study. Average age of respondents was between 18-24 years old. A total of 33 AD had been taken when the students were standing and sitting. Collected data was then processed for analysis in the form of mean, standard deviation. 5th percentile and 95th percentile. Tables 7.1 and 7.2 summarize the AD obtained to represent the current student population within the Politeknik Kuching Sarawak, Malaysia. Figure 7.2 shows the overall AD of students, aged 18-24 years old.

TABLE 7.1

Overall Anthropometric Data of Students, Aged 18-24 Years Old (N = 500)

No.

Dimension

Mean

Std Dev

5th

Percentile

95th

Percentile

1

Age (years)

20.13

1.02

19.00

22.00

2

Weight (kg)

64.69

16.83

46.00

99.00

3

Stature

168.23

6.04

159.61

178.10

4

Eye height

156.51

6.56

146.80

166.70

5

Shoulder height

139.23

6.16

131.11

148.99

6

Elbow height

106.29

4.55

99.81

114.08

7

Fist (grip axis) height

72.00

4.80

64.40

78.88

8

Shoulder (biacromial) breadth

43.54

3.20

39.33

49.88

9

Elbow-to-elbow breadth

45.77

4.42

39.90

54.38

10

Thigh clearance

15.03

2.33

11.71

19.69

11

Abdominal depth, sitting

18.52

3.70

14.11

27.67

12

Knee height

52.10

4.78

44.26

59.95

13

Hip breadth, sitting

31.30

3.80

27.11

39.15

14

Hand length

18.62

1.23

17.20

20.10

15

Hand breadth at metacarpals

7.02

0.62

6.30

8.39

16

Hand thickness

2.94

0.35

2.31

3.50

17

Thumb breadth

2.03

0.17

1.80

2.30

18

Index finger breadth, proximal

1.58

0.14

1.40

1.80

19

Sitting height (erect)

84.21

3.90

77.91

90.60

20

Eye height, sitting

72.53

4.05

66.71

78.69

21

Shoulder height, sitting

56.11

3.27

51.20

61.89

22

Elbow height, sitting

19.45

3.21

14.92

25.60

23

Elbow grip length

33.65

2.48

29.81

37.69

24

Grip reach; forward reach

73.87

4.22

67.50

80.50

25

Vertical grip reach, standing

200.79

8.39

186.52

215.37

26

Buttock-popliteal length (seat depth)

49.20

3.29

43.20

54.40

27

Buttock knee length

60.69

2.99

55.60

65.90

28

Buttock heel length

109.01

5.19

100.90

117.59

29

Lower leg length (popliteal height)

41.20

1.40

39.21

44.00

30

Foot length

25.53

1.22

23.60

27.60

31

Foot breadth

9.70

0.65

8.80

10.80

32

Head length

18.01

0.82

16.90

19.30

33

Head breadth

15.07

0.78

13.91

16.30

34

Head height

23.89

1.38

21.20

25.90

35

Head circumference

55.49

1.77

52.61

58.40

No.

Dimension

Male

Female

Mean

Std Dev

5th

Percentile

95th

Percentile

Mean

Std Dev

5th

Percentile

95th

Percentile

1

Age (years)

20.13

1.02

19.00

22.00

20.05

1.21

19.00

22.00

2

Weight (kg)

64.69

16.83

46.00

99.00

54.95

11.04

40.00

75.00

3

Stature

168.23

6.04

159.61

175.10

155.81

5.45

146.31

163.60

4

Eye height

156.51

6.56

146.30

166.70

144.51

5.44

134.12

152.88

5

Shoulder height

139.23

6.16

131.11

148.99

123.41

5.77

119.80

138.50

6

Elbow height

106.29

4.55

99.31

114.08

98.42

4.90

89.73

106.20

7

Fist (grip axis) height

72.00

4.80

64.40

78.88

66.26

4.66

59.10

73.00

8

Shoulder (biacromial) breadth

43.54

3.20

39.33

49.88

37.31

2.65

33.53

42.18

9

Elbow-to-elbow breadth

45.77

4.42

39.90

54.38

41.75

3.79

35.70

49.00

10

Thigh clearance

15.03

2.33

11.71

19.69

13.45

2.37

9.81

17.50

11

Abdominal depth, sitting

18.52

3.70

14.11

27.67

17.41

3.02

13.41

23.29

12

Knee height

52.10

4.78

44.26

59.95

50.10

2.31

46.31

53.89

13

Hip breadth, sitting

31.30

3.80

27.11

39.15

30.90

4.20

25.51

38.10

14

Hand length

18.62

1.23

17.20

20.10

16.73

1.20

14.50

18.50

15

Hand breadth at metacarpals

7.02

0.62

6.30

8.39

6.58

0.78

5.21

7.60

16

Hand thickness

2.94

0.35

2.31

3.50

2.39

0.29

2.00

2.80

17

Thumb breadth

2.03

0.17

1.80

2.30

1.74

0.18

1.41

2.00

18

Index finger breadth, proximal

1.58

0.14

1.40

1.30

1.52

0.16

1.30

1.80

19

Sitting height (erect)

84.21

3.90

77.91

90.60

7S.37

4.18

72.20

34.79

20

Eye height, sitting

72.53

4.05

66.71

78.69

67.69

4.42

60.50

74.79

(Continued)

No.

Dimension

Male

Female

Mean

Std Dev

5th

Percentile

95th

Percentile

Mean

Std Dev

5th

Percentile

95th

Percentile

21

Shoulder height, sitting

56.11

3.27

51.20

61.89

52.07

3.90

44.41

59.05

22

Elbow height, sitting

19.45

3.21

14.92

25.60

19.00

3.27

13.22

24.10

23

Elbow grip length

33.65

2.48

29.81

37.69

34.31

4.26

28.91

41.89

24

Grip reach, forward reach

73.87

4.22

67.50

80.50

66.88

3.90

59.12

73.30

25

Vertical grip reach, standing

200.79

8.39

186.52

215.37

184.18

8.16

171.50

196.53

26

Buttock-popliteal length (seat depth)

49.20

3.29

43.20

54.40

45.73

3.70

40.30

52.68

27

Buttock knee length

60.69

2.99

55.60

65.90

56.32

3.60

49.73

62.99

28

Buttock heel length

109.01

5.19

100.90

117.59

100.17

4.88

93.12

103.69

29

Lower leg length (popliteal height)

41.20

1.40

39.21

44.00

39.39

2.48

33.53

42.70

30

Foot length

25.53

1.22

23.60

27.60

22.74

1.40

20.10

24.90

31

Foot breadth

9.70

0.65

8.80

10.80

8.58

0.84

7.20

9.70

32

Head length

18.01

0.82

16.90

19.30

18.26

1.88

17.00

22.50

33

Head breadth

15.07

0.78

13.91

16.30

14.45

1.18

12.80

17.07

34

Head height

23.89

1.38

21.20

25.90

22.05

1.30

20.00

24.30

35

Head circumference

55.49

1.77

52.61

58.40

54.59

2.73

50.15

58.60

Overall anthropometric data of students, aged 18-24 years old (n = 500)

FIGURE 7.2 Overall anthropometric data of students, aged 18-24 years old (n = 500).

Table 7.1 presents the descriptive statistics of anthropometric dimensions for the overall population. Figure 7.2 is the graphical representation of Table 7.1. Hence from Table 7.1 and Figure 7.2, it can be seen that the average student height was

162.02 cm while the standard deviation for the student height was 8.46 cm. This shows the difference in standing height being relatively high for students, which is supported by a previous study carried out by Darliana (2008). For the 90th percentile of student height, the ranges are from 148.16 to 176.78 cm. From Table 7.1 and Figure 7.2, it is also known that the mean popliteal student height is 40.29 cm with standard deviation 2.21 cm, while the 5th percentile and 95th percentile are 35.50 cm and 43.20 cm, respectively. This means that a suitable chair design for polytechnic students should be within the range of the 90th percentile of the student population.

Table 7.2 presents the descriptive statistics of anthropometric dimensions for the males and females. Figure 7.3 is the graphical representation of Table 7.2. Hence Table 7.2 and Figure 7.3 show the comparison of AD values for male students against the female students. Overall, male AD exceeded female students, and this is normal as men are typically taller compared to women. The comparison involves data values for mean, standard deviation, 5th percentile, and 95th percentile. From the table we see a significant difference for mean weight of male students compared to the mean weight of females where the mean value is 64.69 kg and 54.95 kg, respectively. This can be used as a guide in selecting the type of material for seat design that can accommodate the weight among students in polytechnics. In addition, it can be seen that there is almost no difference in the mean value of the elbows while sitting between male and female students. The mean value is 19.45 cm for male students and 19.00 cm for female students. In addition, the standard deviation values between students are 3.21 cm and 3.27 cm, respectively.

Anthropometric data for male (n = 213) and female (n = 287)

FIGURE 7.3 Anthropometric data for male (n = 213) and female (n = 287).

Figures 7.4 and 7.5 show the average width of the male students is 31.30 cm while the width of the female students is 30.90 cm. According to Dlugos (1999) and Deros et al. (2009), the width of the female hips is greater than that of male. The difference in the value of AD may be due to the age range used in this study between 18-24 years compared to 18-80 years by previous researchers.

The normal distribution graph of the hip width for female students

FIGURE 7.5 The normal distribution graph of the hip width for female students.

Anthropometric Data Comparison between Students with Chair Dimensions

Comparative Overview of Students

A comparison of AD among genders is made to look at the comfort level of the chairs used. The number of AD taken was 500 students, 213 males and 287 females.

To determine the comfort of the chairs that was used, the comparison is made between the AD of the students against the dimensions of the seat. This comparison includes AD of the popliteal height against the height of the chair (Figure 7.6)

Percentage of total student matching chairs depth for buttock-popliteal length

FIGURE 7.7 Percentage of total student matching chairs depth for buttock-popliteal length.

and buttock-popliteal length against the seat depth (Figure 7.7). Figure 7.6 shows the percentage of all students who match the seat for a popliteal height. From Figure 7.6, only 8% of the number of students are matching the height of the chair and are in the 90th percentile of the student population. Also, it has to be noted that, 83% of students are too tall at the popliteal height point. The low percentage of students indicates that the height of the chair in the classroom does not match the polytechnic students’ AD.

Figure 7.7 shows the percentage of students w'ho fit the seat for buttock-popliteal length. From the figure it is showm that only 3% of the 90th percentile student population fits with seat depth, w'hereas 71% of the population are matching for the 5th percentile of buttock-popliteal length. This small percentage value indicates that most of the students do not match the existing seat depth. Therefore, a new chair design should be proposed to provide comfort and safety to students using the chairs.

Comparison between Genders

Comparison of AD among genders is made to look at the comfort level of seat use. The number of respondents consisted of 213 males and 287 females.

Figure 7.8 show's the percentage of male students matching the height of chair for their popliteal height. The percentage of male students w'ho match the chair height is 15% male students of the 90th percentile of popliteal height. Meanwhile, 57% of male students are taller than the 95th percentile popliteal height. For the male students, there is no mismatch for the 5th percentile population.

Figure 7.9 shows the percentage of female students matching the seat for popliteal height. From the figure it is shown that only 3% of students are fitting with the height of the chair and 97% are matching at popliteal height for over

Percentage of male students matching the seat for a popliteal height

FIGURE 7.8 Percentage of male students matching the seat for a popliteal height.

95th percentile of the population. This shows that male and female students with popliteal height over 95th percentile should ideally be corresponding to the height of chairs. In addition, the difference in the percentage of mismatched male and female students is normal. This is because of the fact that men are usually taller than women.

Figures 7.10 and 7.11 show the percentage of male and female students w'ho match the seats for the buttock popliteal length. The buttock popliteal length is compared

Percentage of male students matching the seat for the buttock popliteal length

FIGURE 7.10 Percentage of male students matching the seat for the buttock popliteal length.

to the width of the seat, that is, the distance from the back to the front of the seat surface. From Figure 7.10, there is no percentage of male students matching the seat seating dimensions. In contrast, from Figure 7.11, there are 10% of female students who match the 95th percentile of the population of polytechnic students. This indicates that the female buttock popliteal length is shorter than men and this causes the male student to feel uncomfortable while sitting for a long time on the chair. For a student population of the 5th percentile, 1% of the male students and 5% for female students are within comfortable range.

Percentage of female students matching the seat for the buttock popliteal length

FIGURE 7.11 Percentage of female students matching the seat for the buttock popliteal length.

TABLE 7.3

Comparison of Anthropometric Data with Dimensions of Furniture in the Classroom

Furniture

Parameters

Dimension

Anthropometry

Student

Anthropometry Data (cm)

Current Furniture Dimensions (cm)

Chair

Chair width

Buttock popliteal length

40.30

40.00

Chair height

Popliteal height

33.53^43.70

43.38

Backrest height

Height of shoulder when sitting

44.41

34.00

Saddle length

Hip width

39.15

48.50

Backrest length

Shoulder width

49.88

48.00

Mismatches between Chair

The combinations of chairs are not a proper fit and this causes discomfort and pain in some parts of the body, for example, the neck, shoulder, waist and arm of the body. The furniture dimension mismatch also makes the students constantly try to adjust the use of chairs with tables.

Table 7.3 shows the comparison between students’ AD and existing seat dimensions.

All in all, comparison between students’ AD and design dimensions of the classroom furniture is summarized in Table 7.4. It can be observed that there exist several mismatches based on the design standards for furniture.

Data obtained from anthropometric dimensions indicates that there are a lot of differences even between people from the same country who make up the population of students in polytechnics across Malaysia. There is a mismatch between the anthropometric dimensions and the current furniture used in classrooms of Politeknik Kuching, Sarawak, Malaysia. From the comparison result, several mismatches were found and this leads to the conclusion that the design of furniture used in the classroom needs to be improved to better accommodate the studying

TABLE 7.4

New Dimensions of the Furniture to Match the Anthropometric Data

Furniture

Parameters

Student

Anthropometry Data (cm)

Dimension Anthropometry (Baba et al., 2008)

Recommended New Dimension of Furniture (cm)

Chair

Chair width

40.00

39.00

40.00

Chair height

33.00-44.00

38.00-53.00

36.00-49.00

Backrest height

44.00

46.44

45.00

Saddle length

39.00

48.00

44.00

Backrest length

50.00

50.00

Finalized engineering drawing for composite polytechnic chair (units in mm)

FIGURE 7.12 Finalized engineering drawing for composite polytechnic chair (units in mm).

process of the students. The scenario can also be extended to other polytechnics and universities in Malaysia. The study results provide the necessary support to the idea that there are ongoing problems with the design of chairs in the current polytechnic classroom, and this is the solid background for the design of new biocomposite chairs based on AD.

Detail Design of Biocomposite Chair with Inputs from AD

A detail drawing of the selected concept of biocomposite polytechnic chair with inputs from AD is shown in Figure 7.12. An important activity in this study is the development of biocomposite for polytechnic chairs. The density and mechanical properties of biocomposite material are shown in Table 7.5. The final selected

TABLE 7.5

Density and Mechanical Properties of Biocomposite Material (Sathishkumar, 2016)

Density (g/cm1)

Tensile Strength (MPa)

Tensile Modulus (GPa)

Elongation (%)

692

10.94

4.3

930

53

1.6

1.45

930

53

1.6

1.4

284-800

21-60

1.6

1.5

350-600

40

2.5-3.5

0.75

400-550

0.6

_

_

_

0.749

223-624

11-14.5

2.7-5.7

1.2

295

3-10

Subcomponents for the composite polytechnic chair

FIGURE 7.13 Subcomponents for the composite polytechnic chair.

concept was chosen because it scored the highest value of the weighted objectives and hence is the best solution. Figure 7.12 shows the engineering drawing of the composite polytechnic chair with dimensions using Autodesk Inventor 2015 software.

The subcomponents for the composite polytechnic chair have also been extensively designed. This is shown in Figure 7.13.

 
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