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Investigation into the occupational ride comfort due to exposure of whole body vibration
CHAPTER 10
Investigation into the occupational ride comfort due to exposure of whole body vibration Amandeep Singh1, Lakhwinder Pal Singh1, Harwinder Singh2 and Sarbjit Singh1 1
Department of Industrial and Production Engineering, Dr. B R Ambedkar National Institute of Technology, Jalandhar, India; Department of Mechanical Engineering, Guru Nanak Dev Engineering College, Ludhiana, India
2
10.1 Introduction In current technological era, agricultural sector has influenced manual labor as well as characteristics of workload [1]. Around 3 million population are having tractors with an average growth of 0.25 million tractors per year in current Indian scenario. Tillage is an essential agricultural activity for preparing soil to develop optimum conditions ideal for seed germination, seedling establishment and growth of crops. A number of primary and secondary soil tillage operation are required in every agricultural field. The tillage operation that is done after the harvest of crop to bring the land under cultivation is known as primary tillage or plowing. The tillage operations that are performed on the soil after primary tillage to bring a good soil tilth are known as secondary tillage. Cultivation is a secondary tillage operation performed by toothed type cultivator often similar to chisel plows. This is mounted to tractor by means of a three-point hitch and driven by a power take-off (PTO). Tractor and its mounted implements give rise to vibration during interactions with uneven terrains [1]. Vibrations transmits to driver through many sources that affects ride behavior [2]. Prolonged exposure to vibrations are results into low back disorders among tractor drivers [3]. This may due the reason of high amplitudes to which a tractor driver is exposed during off-road operations [4]. Many researchers have investigated the influence of vibrations on human ride comfort under varying: vibration magnitudes, postures, backrest conditions, type of excitation, foot conditions [59]. These studies are performed on simulators under controlled laboratory environment. Many studies are carried to investigate human vibration exposure in real-field conditions by considering varying vehicle speed, terrain conditions, subject variability, and posture variations [1013]. Moreover, such investigations are less explored in real field soil tillage operations. There could a major influence of various factors like forward Smart Healthcare for Disease Diagnosis and Prevention DOI: https://doi.org/10.1016/B978-0-12-817913-0.00010-9
r 2020 Elsevier Inc. All rights reserved.
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speed, pulling force, and tilling depth on vibration exposures and thereby affecting the ‘ovtv’ response. This study is also focused to improve the existing tractor because most the farmers in developing countries are not much capable to buy expensive tractors with advances technology. It is important to explore optimum driving conditions in order to improve ride comfort. This could only be possible by carrying out a significant number of experiments to study the effect of accounting factors on ride behavior. Full factorial design methods give a large number of experiments that might be tedious to perform in real conditions. Taguchi’s method provides a minimum set of experiments to get optimum conditions to improve the response factor [14]. Therefore, the present study is an attempt to investigate the effect of forward speed, pulling force, and tilling depth on overall vibration total value by using Taguchi’s method.
10.2 General details A 24 years male subject having stature 1.542 m, weight 81 kg and body mass index 34.07 kg/m2 participated in study. The subject was randomly selected with an at least experience of 5 years in tractor driving. Study was carried out on post harvested paddy field situated at Punjab Agriculture University, Ludhiana, Punjab, India. 50 hp tractor ‘T’ of 2014 model has been selected for the study. A 13 tines cultivator with length 3048 m and working width 2.3 m was mounted with tractor for carrying out cultivation operation as shown in Fig. 10.1. The ride comfort was determined in terms of “overall vibration total value (ovtv)” response. The vibration response measurement at only seat location has not been
Figure 10.1 Tractor mounted with cultivator.
Investigation into the occupational ride comfort due to exposure of whole body vibration
Figure 10.2 Apparatus mounting locations.
sufficient to determine ride comfort [15]. Therefore, ‘ovtv’ response has been determined by recording whole body vibration levels at three locations i.e. floor, seat-pan, and backrest as shown in Fig. 10.2.
10.3 Measurement devices/equipments The whole-body vibration levels were recorded in terms of acceleration weighted root mean squared (rms) values along fore-and-aft (x), lateral (y), and vertical (z) axes, respectively. The floor vibrations were recorded by using 4-channel SV 958 vibration analyzer (a). Seat and backrest vibration were recorded by using two SVAN 106 human vibration monitors (b & c) mounted at individual locations as shown in Fig. 10.2. The measurement and calculations were done as per ISO 2631-1 (1997) standard.
10.4 Experimental design and data analysis The aim of Taguchi’s method was to reduce the ‘ovtv’ by obtaining optimum conditions of affecting input factors. Therefore, S/N ratios were computed by considering “smaller-the-better” option in Minitab 17.0 software package. The study includes three input factors with three levels i.e. forward speed (1.3, 1.5, 1.7 m/s), pulling force (2, 4, 6 kN), tilling depth (0.1, 0.13, 0.16 m) as shown in Table 10.1. Taguchi’s L27 orthogonal array has been selected to design the experimental runs. It provided 27 no. of experiments with varying combinations of input factors and each experiment was replicated by 5 times to obtain an average S/N ratio. The computed S/N ratio were analyzed by considering “smaller-the-better” option in order to
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Table 10.1 Input factors and their levels. Levels
1 2 3
Input factors A: Forward speed (m/s)
B: Pulling force (kN)
C: Tilling depth (m)
1.3 1.5 1.7
2 4 6
0.10 0.13 0.16
minimize output response characteristic. The maximum value of S/N ratio will represent the optimum level for each input factor. Table 10.2 shows the experimental design as per Taguchi’s L27 orthogonal array and the results of five replications for each trial is reported. An average value from each set of replications is calculated to compute S/N ratio. As the study aimed to minimize the output characteristic i.e. ‘ovtv’, so a mathematical formula for ‘smaller-the-better’ option is used to obtain S/N ratios for response characteristic i.e. ‘ovtv’, so a mathematical formula for ‘smallerthe-better’ option is used to obtain S/N ratios for response characteristic i.e. ‘ovtv’, so a mathematical formula for ‘smaller-the-better’ option is used to obtain S/N ratios for response characteristic is: [16] S=N ¼ -10log½1=Rðy1 ^2 þ y2 ^2 þ . . . þ yn ^2Þ It is observed that the mean overall vibration total value in this tillage operations ranges from 0.625 to 0.831 m/s2. The trials representing minimum and maximum ‘ovtv’ response and corresponding S/N ratio values are highlighted as shown on Table 10.2. It is noticed that the trial contributing minimum ‘ovtv’ is having maximum S/N ratio and similarly, minimum S/N ratio for trial with maximum ‘ovtv’ response. The computed S/N ratios are further used to obtain optimum levels of input parameters for getting reduced ‘ovtv’. Fig. 10.3 represents the trend of S/N ratios with respect to selected input factors and their respective levels. The optimum conditions of each input factor are represented by highest S/N ratio i.e. the significant conditions of forward Speed, pulling force and tilling depth are 1.3 m/s, 6 kN and 0.16 m respectively. It can be observed that at these optimum conditions are giving minimum values of ‘ovtv’ as in Table 10.2. Moreover, the mean ‘ovtv’ response increases with increase in forward speed and it get decreases with increase in pulling force. This increase in ‘ovtv’ is due to the increase in vibrations which could be caused by accelerating speeds on uneven terrains [17]. The ‘ovtv’ tends to decrease suddenly with increase in the tilling depth from 0.10 to 0.13 m, however this change represents a slight decrease with increase in tilling depth from 0.13 to 0.16 m. It means that the whole-body vibrations get absorbed
Investigation into the occupational ride comfort due to exposure of whole body vibration
Table 10.2 Experimental design and results of L27 orthogonal array. Trial no.
Output (OVTV) m/s2
Input factors A
B
C
R1
R2
Trial conditions
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27
1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3
1 1 1 2 2 2 3 3 3 1 1 1 2 2 2 3 3 3 1 1 1 2 2 2 3 3 3
1 1 1 2 2 2 3 3 3 2 2 2 3 3 3 1 1 1 3 3 3 1 1 1 2 2 2
R3
S/N (dB)
R4
R5
Mean
0.740 0.730 0.707 0.665 0.650 0.685 0.629 0.636 0.653 0.789 0.779 0.792 0.745 0.737 0.765 0.730 0.755 0.747 0.819 0.823 0.847 0.813 0.755 0.783 0.756 0.743 0.787
0.730 0.735 0.746 0.660 0.652 0.700 0.652 0.623 0.659 0.807 0.797 0.757 0.749 0.748 0.796 0.725 0.785 0.756 0.833 0.813 0.814 0.806 0.795 0.830 0.765 0.727 0.785
0.726 0.733 0.723 0.677 0.663 0.683 0.646 0.625 0.646 0.799 0.786 0.775 0.742 0.756 0.780 0.734 0.766 0.752 0.831 0.823 0.822 0.807 0.773 0.800 0.776 0.733 0.783
Replications
0.719 0.737 0.724 0.668 0.653 0.676 0.634 0.622 0.640 0.809 0.787 0.766 0.740 0.756 0.780 0.724 0.756 0.742 0.829 0.833 0.812 0.807 0.763 0.800 0.790 0.724 0.774
0.734 0.717 0.700 0.684 0.676 0.660 0.648 0.614 0.636 0.780 0.770 0.786 0.719 0.773 0.767 0.737 0.776 0.752 0.832 0.834 0.823 0.787 0.760 0.783 0.789 0.742 0.765
0.709 0.745 0.736 0.706 0.686 0.693 0.669 0.629 0.642 0.808 0.797 0.772 0.756 0.766 0.790 0.752 0.756 0.765 0.843 0.814 0.816 0.823 0.790 0.806 0.780 0.731 0.803
2.766
3.423
3.888
2.087
2.392
2.491
1.663
2.009
2.335
A, B and C: Input factors; R1, R2, R3, R4 and R5: Number of replications for each respective set of trial.
while increasing tilling depth. The analysis of variance (ANOVA) is performed to investigate the influence of each input factor on the output characteristic with respect to significance level as shown in Table 10.3. The sequential sum of squares (Seq SS), adjusted mean squares (Adj MS), F-value (F), significance level (p) are represented in Table 10.3. It is observed that forward speed and pulling force have significant effect on overall vibration total value at 95% significance level. However, the tilling depth is found to have insignificant contribution in output response. Further, the percentage contribution (P%) of each input factor is determined by diving individual sequential sum of square value by
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Figure 10.3 Main effects plot for signal to noise (S/N) ratios.
Table 10.3 Analysis of variance for overall vibration total value. Source
dof
Seq SS
Adj MS
F
p
P%
Forward Speed Pulling Force Tillage Depth Residual Error Total
2 2 2 2 8
0.021135 0.005831 0.000490 0.000222 0.027678
0.010567 0.002916 0.000245 0.000111
95.23 26.27 2.21
0.01* 0.04* 0.31
76.36 21.07 1.77 0.80 100.00
total sequential sum of square and multiplied by 100 as per [18]. The forward seed (76.36%) is found to be most contributing input factor to affect the ‘ovtv’ followed by pulling force (21.07%), and tilling depth (1.77%) respectively. Further, the ranking of each input factor is determined by using delta values as shown in Table 10.4. The delta is calculated by taking the difference between maximum and minimum signal-to noise ratio. The delta value indicates the impact index on output characteristic. It is observed that the forward speed has maximum delta value, thereby ranked 1st followed by pulling force and tilling depth with respect to their influence on ‘ovtv’.
Investigation into the occupational ride comfort due to exposure of whole body vibration
Table 10.4 Response table for signal to noise (S/N) ratios (smaller-the-better). Level
1 2 3 Delta Rank
Input factors Forward speed (m/s)
Pulling force (kN)
Tilling depth (m)
3.359 2.323 2.002 1.357 1
2.172 2.608 2.904 0.732 2
2.422 2.615 2.648 0.226 3
10.5 Conclusions The following conclusions have been drawn from the present study: The ride comfort in cultivation operation is found fairly uncomfortable to uncomfortable as per overall vibration total value response. The optimum level of forward speed, pulling force, and tilling depth are 1.3 m/s, 6 kN, and 0.16 m to improve ride comfort by minimum overall vibration total value. Forward speed and pulling force are found significant at 95% significance level. The delta value of forward speed is maximum followed by pulling force and tilling depth respectively.
Acknowledgment The authors would acknowledge The Institution of Engineers (IEI), India for assisting this research work with financial support [Grant Code: RDDR2016067]. Authors would also like to thank The Department of Farm Machinery and Power Engineering, Punjab Agricultural University, Ludhiana, Punjab, India for providing experimental facilities. The authors would also thank the ‘Welan Technologies’ for providing their guidance towards instrumentation during the experimentation.
References [1] C.R. Mehta, P.S. Tiwari, A.C. Varshney, Ride vibrations on a 7 5kw rotary power tiller, J. Agric. Eng. Res. 66 (3) (1997) 169176. [2] J. Village, C. Trask, Y. Chow, J.B. Morrison, M. Koehoorn, K. Teschke, Assessing whole body vibration exposure for use in epidemiological studies of back injuries: measurements, observations and self-reports, Ergonomics 55 (4) (2012) 415424. [3] I.J.H. Tiemessen, C.T.J. Hulshof, M.H.W. Frings-Dresen, Low back pain in drivers exposed to whole body vibration: analysis of a dose-response pattern, Occup. Environ. Med. 65 (10) (2008) 667675. [4] M.J. Griffin, Vibration and human responses, Handb. Hum. Vib., 1990, pp. 125. [5] H. Ciloglu, M. Alziadeh, A. Mohany, H. Kishawy, Assessment of the whole body vibration exposure and the dynamic seat comfort in passenger aircraft, Int. J. Ind. Ergon. 45 (2015) 116123. [6] S. Rakheja, R.G. Dong, S. Patra, P.-É. Boileau, P. Marcotte, C. Warren, Biodynamics of the human body under whole-body vibration: Synthesis of the reported data, Int. J. Ind. Ergon. 40 (6) (2010) 710732.
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[7] N. Nawayseh, M.J. Griffin, A model of the vertical apparent mass and the fore-and-aft cross-axis apparent mass of the human body during vertical whole-body vibration, J. Sound Vib. 319 (12) (2009) 719730. [8] S.K. Patra, S. Rakheja, H. Nelisse, P.-É. Boileau, J. Boutin, Determination of reference values of apparent mass responses of seated occupants of different body masses under vertical vibration with and without a back support, Int. J. Ind. Ergon. 38 (56) (2008) 483498. [9] S. Rakheja, I. Haru, P.-é. Boileau, Seated occupant apparent mass characteristics under automotive postures and vertical vibration, J. Sound Vib. 253 (1) (2002) 5775. Available from: https://doi. org/10.1006/jsvi.2001.4249. [10] A. Singh, L.P. Singh, S. Singh, H. Singh, N.K. Chhuneja, M. Singh, Evaluation and analysis of occupational ride comfort in rotary soil tillage operation, Measurement, Measurement 131 (2009) 1927. Available from: https://doi.org/10.1016/j.measurement.2018.08.046. [11] A. Singh, N. Nawayseh, L.P. Singh, S. Singh, H. Singh, Whole body vibration exposure during rotary soil tillage operation: the relative importance of tractor speed, pulling force and tilling depth, Int. J. Auto. Mech. Eng. 15 (4) (2019) 59275940. Available from: https://doi.org/10.15282/ ijame.15.4.2018.15.0452. [12] A. Singh, N. Nawayseh, L.P. Singh, S. Singh, H. Investigation into the compressive stress on lumbar spine due to whole body vibration exposure in rotary tillage operation, Int. J. Auto. Mech. Eng. 16 (2) (2019) 66846696. Available from: https://doi.org/10.15282/ijame.16.2.2019.16.0503. [13] A. Singh, L.P. Singh, S. Singh, H. Singh, Investigation of whole body vibration transmission responses among Indian tractor drivers, Int. J. Veh. Perform. 5 (2) (2018) 286299. Available from: https://doi.org/10.1504/ijvp.2019.100705. [14] M.-L. Huang, Y.-H. Hung, Z.-S. Yang, Validation of a method using Taguchi, response surface, neural network, and genetic algorithm, Measurement 94 (2016) 284294. Available from: https:// doi.org/10.1016/j.measurement.2016.08.006. [15] I.H. Wyllie, M.J. Griffin, Discomfort from sinusoidal oscillation in the roll and lateral axes at frequencies between 0.2 and 1.6Hz, J. Acoust. Soc. Am. 121 (5) (2007) 26442654. Available from: https://doi.org/10.1121/1.2715654. [16] R.K. Roy, A Primer on the Taguchi Method, Competitive Manufacturing Series, New York, 1990. [17] Vrielink, H.H.O., Exposure to whole-body vibration and effectiveness of chair damping in highpower agricultural tractors Report (2012-0601). ErgoLab Research BV (2009). [18] H.R. Lindman, Analysis of Variance in Experimental Design, Springer Science & Business Media, New York, 2012.
Investigation into the occupational ride comfort due to exposure of whole body vibration Amandeep Singh1, Lakhwinder Pal Singh1, Harwinder Singh2 and Sarbjit Singh1 1
Department of Industrial and Production Engineering, Dr. B R Ambedkar National Institute of Technology, Jalandhar, India; Department of Mechanical Engineering, Guru Nanak Dev Engineering College, Ludhiana, India
2
10.1 Introduction In current technological era, agricultural sector has influenced manual labor as well as characteristics of workload [1]. Around 3 million population are having tractors with an average growth of 0.25 million tractors per year in current Indian scenario. Tillage is an essential agricultural activity for preparing soil to develop optimum conditions ideal for seed germination, seedling establishment and growth of crops. A number of primary and secondary soil tillage operation are required in every agricultural field. The tillage operation that is done after the harvest of crop to bring the land under cultivation is known as primary tillage or plowing. The tillage operations that are performed on the soil after primary tillage to bring a good soil tilth are known as secondary tillage. Cultivation is a secondary tillage operation performed by toothed type cultivator often similar to chisel plows. This is mounted to tractor by means of a three-point hitch and driven by a power take-off (PTO). Tractor and its mounted implements give rise to vibration during interactions with uneven terrains [1]. Vibrations transmits to driver through many sources that affects ride behavior [2]. Prolonged exposure to vibrations are results into low back disorders among tractor drivers [3]. This may due the reason of high amplitudes to which a tractor driver is exposed during off-road operations [4]. Many researchers have investigated the influence of vibrations on human ride comfort under varying: vibration magnitudes, postures, backrest conditions, type of excitation, foot conditions [59]. These studies are performed on simulators under controlled laboratory environment. Many studies are carried to investigate human vibration exposure in real-field conditions by considering varying vehicle speed, terrain conditions, subject variability, and posture variations [1013]. Moreover, such investigations are less explored in real field soil tillage operations. There could a major influence of various factors like forward Smart Healthcare for Disease Diagnosis and Prevention DOI: https://doi.org/10.1016/B978-0-12-817913-0.00010-9
r 2020 Elsevier Inc. All rights reserved.
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speed, pulling force, and tilling depth on vibration exposures and thereby affecting the ‘ovtv’ response. This study is also focused to improve the existing tractor because most the farmers in developing countries are not much capable to buy expensive tractors with advances technology. It is important to explore optimum driving conditions in order to improve ride comfort. This could only be possible by carrying out a significant number of experiments to study the effect of accounting factors on ride behavior. Full factorial design methods give a large number of experiments that might be tedious to perform in real conditions. Taguchi’s method provides a minimum set of experiments to get optimum conditions to improve the response factor [14]. Therefore, the present study is an attempt to investigate the effect of forward speed, pulling force, and tilling depth on overall vibration total value by using Taguchi’s method.
10.2 General details A 24 years male subject having stature 1.542 m, weight 81 kg and body mass index 34.07 kg/m2 participated in study. The subject was randomly selected with an at least experience of 5 years in tractor driving. Study was carried out on post harvested paddy field situated at Punjab Agriculture University, Ludhiana, Punjab, India. 50 hp tractor ‘T’ of 2014 model has been selected for the study. A 13 tines cultivator with length 3048 m and working width 2.3 m was mounted with tractor for carrying out cultivation operation as shown in Fig. 10.1. The ride comfort was determined in terms of “overall vibration total value (ovtv)” response. The vibration response measurement at only seat location has not been
Figure 10.1 Tractor mounted with cultivator.
Investigation into the occupational ride comfort due to exposure of whole body vibration
Figure 10.2 Apparatus mounting locations.
sufficient to determine ride comfort [15]. Therefore, ‘ovtv’ response has been determined by recording whole body vibration levels at three locations i.e. floor, seat-pan, and backrest as shown in Fig. 10.2.
10.3 Measurement devices/equipments The whole-body vibration levels were recorded in terms of acceleration weighted root mean squared (rms) values along fore-and-aft (x), lateral (y), and vertical (z) axes, respectively. The floor vibrations were recorded by using 4-channel SV 958 vibration analyzer (a). Seat and backrest vibration were recorded by using two SVAN 106 human vibration monitors (b & c) mounted at individual locations as shown in Fig. 10.2. The measurement and calculations were done as per ISO 2631-1 (1997) standard.
10.4 Experimental design and data analysis The aim of Taguchi’s method was to reduce the ‘ovtv’ by obtaining optimum conditions of affecting input factors. Therefore, S/N ratios were computed by considering “smaller-the-better” option in Minitab 17.0 software package. The study includes three input factors with three levels i.e. forward speed (1.3, 1.5, 1.7 m/s), pulling force (2, 4, 6 kN), tilling depth (0.1, 0.13, 0.16 m) as shown in Table 10.1. Taguchi’s L27 orthogonal array has been selected to design the experimental runs. It provided 27 no. of experiments with varying combinations of input factors and each experiment was replicated by 5 times to obtain an average S/N ratio. The computed S/N ratio were analyzed by considering “smaller-the-better” option in order to
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Table 10.1 Input factors and their levels. Levels
1 2 3
Input factors A: Forward speed (m/s)
B: Pulling force (kN)
C: Tilling depth (m)
1.3 1.5 1.7
2 4 6
0.10 0.13 0.16
minimize output response characteristic. The maximum value of S/N ratio will represent the optimum level for each input factor. Table 10.2 shows the experimental design as per Taguchi’s L27 orthogonal array and the results of five replications for each trial is reported. An average value from each set of replications is calculated to compute S/N ratio. As the study aimed to minimize the output characteristic i.e. ‘ovtv’, so a mathematical formula for ‘smaller-the-better’ option is used to obtain S/N ratios for response characteristic i.e. ‘ovtv’, so a mathematical formula for ‘smallerthe-better’ option is used to obtain S/N ratios for response characteristic i.e. ‘ovtv’, so a mathematical formula for ‘smaller-the-better’ option is used to obtain S/N ratios for response characteristic is: [16] S=N ¼ -10log½1=Rðy1 ^2 þ y2 ^2 þ . . . þ yn ^2Þ It is observed that the mean overall vibration total value in this tillage operations ranges from 0.625 to 0.831 m/s2. The trials representing minimum and maximum ‘ovtv’ response and corresponding S/N ratio values are highlighted as shown on Table 10.2. It is noticed that the trial contributing minimum ‘ovtv’ is having maximum S/N ratio and similarly, minimum S/N ratio for trial with maximum ‘ovtv’ response. The computed S/N ratios are further used to obtain optimum levels of input parameters for getting reduced ‘ovtv’. Fig. 10.3 represents the trend of S/N ratios with respect to selected input factors and their respective levels. The optimum conditions of each input factor are represented by highest S/N ratio i.e. the significant conditions of forward Speed, pulling force and tilling depth are 1.3 m/s, 6 kN and 0.16 m respectively. It can be observed that at these optimum conditions are giving minimum values of ‘ovtv’ as in Table 10.2. Moreover, the mean ‘ovtv’ response increases with increase in forward speed and it get decreases with increase in pulling force. This increase in ‘ovtv’ is due to the increase in vibrations which could be caused by accelerating speeds on uneven terrains [17]. The ‘ovtv’ tends to decrease suddenly with increase in the tilling depth from 0.10 to 0.13 m, however this change represents a slight decrease with increase in tilling depth from 0.13 to 0.16 m. It means that the whole-body vibrations get absorbed
Investigation into the occupational ride comfort due to exposure of whole body vibration
Table 10.2 Experimental design and results of L27 orthogonal array. Trial no.
Output (OVTV) m/s2
Input factors A
B
C
R1
R2
Trial conditions
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27
1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3
1 1 1 2 2 2 3 3 3 1 1 1 2 2 2 3 3 3 1 1 1 2 2 2 3 3 3
1 1 1 2 2 2 3 3 3 2 2 2 3 3 3 1 1 1 3 3 3 1 1 1 2 2 2
R3
S/N (dB)
R4
R5
Mean
0.740 0.730 0.707 0.665 0.650 0.685 0.629 0.636 0.653 0.789 0.779 0.792 0.745 0.737 0.765 0.730 0.755 0.747 0.819 0.823 0.847 0.813 0.755 0.783 0.756 0.743 0.787
0.730 0.735 0.746 0.660 0.652 0.700 0.652 0.623 0.659 0.807 0.797 0.757 0.749 0.748 0.796 0.725 0.785 0.756 0.833 0.813 0.814 0.806 0.795 0.830 0.765 0.727 0.785
0.726 0.733 0.723 0.677 0.663 0.683 0.646 0.625 0.646 0.799 0.786 0.775 0.742 0.756 0.780 0.734 0.766 0.752 0.831 0.823 0.822 0.807 0.773 0.800 0.776 0.733 0.783
Replications
0.719 0.737 0.724 0.668 0.653 0.676 0.634 0.622 0.640 0.809 0.787 0.766 0.740 0.756 0.780 0.724 0.756 0.742 0.829 0.833 0.812 0.807 0.763 0.800 0.790 0.724 0.774
0.734 0.717 0.700 0.684 0.676 0.660 0.648 0.614 0.636 0.780 0.770 0.786 0.719 0.773 0.767 0.737 0.776 0.752 0.832 0.834 0.823 0.787 0.760 0.783 0.789 0.742 0.765
0.709 0.745 0.736 0.706 0.686 0.693 0.669 0.629 0.642 0.808 0.797 0.772 0.756 0.766 0.790 0.752 0.756 0.765 0.843 0.814 0.816 0.823 0.790 0.806 0.780 0.731 0.803
2.766
3.423
3.888
2.087
2.392
2.491
1.663
2.009
2.335
A, B and C: Input factors; R1, R2, R3, R4 and R5: Number of replications for each respective set of trial.
while increasing tilling depth. The analysis of variance (ANOVA) is performed to investigate the influence of each input factor on the output characteristic with respect to significance level as shown in Table 10.3. The sequential sum of squares (Seq SS), adjusted mean squares (Adj MS), F-value (F), significance level (p) are represented in Table 10.3. It is observed that forward speed and pulling force have significant effect on overall vibration total value at 95% significance level. However, the tilling depth is found to have insignificant contribution in output response. Further, the percentage contribution (P%) of each input factor is determined by diving individual sequential sum of square value by
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Figure 10.3 Main effects plot for signal to noise (S/N) ratios.
Table 10.3 Analysis of variance for overall vibration total value. Source
dof
Seq SS
Adj MS
F
p
P%
Forward Speed Pulling Force Tillage Depth Residual Error Total
2 2 2 2 8
0.021135 0.005831 0.000490 0.000222 0.027678
0.010567 0.002916 0.000245 0.000111
95.23 26.27 2.21
0.01* 0.04* 0.31
76.36 21.07 1.77 0.80 100.00
total sequential sum of square and multiplied by 100 as per [18]. The forward seed (76.36%) is found to be most contributing input factor to affect the ‘ovtv’ followed by pulling force (21.07%), and tilling depth (1.77%) respectively. Further, the ranking of each input factor is determined by using delta values as shown in Table 10.4. The delta is calculated by taking the difference between maximum and minimum signal-to noise ratio. The delta value indicates the impact index on output characteristic. It is observed that the forward speed has maximum delta value, thereby ranked 1st followed by pulling force and tilling depth with respect to their influence on ‘ovtv’.
Investigation into the occupational ride comfort due to exposure of whole body vibration
Table 10.4 Response table for signal to noise (S/N) ratios (smaller-the-better). Level
1 2 3 Delta Rank
Input factors Forward speed (m/s)
Pulling force (kN)
Tilling depth (m)
3.359 2.323 2.002 1.357 1
2.172 2.608 2.904 0.732 2
2.422 2.615 2.648 0.226 3
10.5 Conclusions The following conclusions have been drawn from the present study: The ride comfort in cultivation operation is found fairly uncomfortable to uncomfortable as per overall vibration total value response. The optimum level of forward speed, pulling force, and tilling depth are 1.3 m/s, 6 kN, and 0.16 m to improve ride comfort by minimum overall vibration total value. Forward speed and pulling force are found significant at 95% significance level. The delta value of forward speed is maximum followed by pulling force and tilling depth respectively.
Acknowledgment The authors would acknowledge The Institution of Engineers (IEI), India for assisting this research work with financial support [Grant Code: RDDR2016067]. Authors would also like to thank The Department of Farm Machinery and Power Engineering, Punjab Agricultural University, Ludhiana, Punjab, India for providing experimental facilities. The authors would also thank the ‘Welan Technologies’ for providing their guidance towards instrumentation during the experimentation.
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