THE HUMAN BODY AND VIBRATION, AN ERGONOMIC APPROACH

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1 THE HUMAN BODY AND VIBRATION, AN ERGONOMIC APPROACH Mr.K.R.Gawande 1 1 Assistant Professor, Deptt. of Mechanical Engineering, Dr.Rajendra Gode college of Engineering & Tech., Amravati Abstract: This paper contains a general presentation of the effect of vibration on human performance. The investigation is evaluated on the equipment such as tractor, road driller and sewing machine. The results revealed that the vibration frequency on the human body part while operating above equipment is very high than the sustainable frequency of the body part. The whole body vibration frequency measurement has revealed the possibility of occupational health hazard for various body parts like legs, shoulder, spinal column and abdominal mass for operator of above equipments. Two common types of vibration exposures identified as deleterious: Hand arm vibration and vibration. These two vibrations are considered in the present case study. Key words:- hand-arm vibration, whole body vibration. I. INTRODUCTION The main objective of this paper is to investigate the human body exposure to vibration.risk to workers from exposure to high levels of vibration include decreased performance and even permanent injury. Two common types of vibration exposures have been identified as vibration (WBV) and vibration. vibration energy enters into the body through a seat or the floor, it affects the entire body or number of organs in the body. When a worker sits or stands on a vibrating floor or seat, the exposure affects almost the entire body and it is called wholebody vibration exposure. Drivers of some mobile machines, including certain tractors, fork lift trucks and earth-moving machinery or those who work on vibrating floors may be exposed to WBV and shocks which are associated with back pain. Many adverse health effects are linked to WBV. These include irritation to the lungs, abdomen and bladder. ISO standard also indicates that WBV adversely affects the digestive or genetic system. vibration comprises the transfer of relatively low frequency environmental vibration to the human body through broad contact area. High level of whole body vibration exposure is common to workers who operate heavy machinery, material handling and transport equipments, or whose operator stations are in proximity to heavy rotating or reciprocating machinery. Hand arm vibration is vibration transmitted from work process into workers hand and arms. It can be caused by operating hand held power tools such as road driller, powered lawnmovers, pedestal grinders etc. The hand arm vibration can cause range of conditions which is collectively known as hand arm vibration syndromes (HAVS),as well as specific diseases such as carpal tunnel syndrome. In present case study the whole body vibration frequency measurement has been done on tractor where as hand-arm vibration frequency measurement has been done on road driller. II. LITERATURE SURVEY Lot of research has been conducted to study the effect of vibration on the accuracy of final product while manufacturing and on the various parts of machine tools. Since man is the important part of any system it is necessary to study the effect of vibration on human body and ultimately it affects the human performance. Efficiency of any operator depends on the comfort conditions provided during working hours. More the comfort condition provided higher will be the efficiency of operator. Researchers have been compiling data over the last few years on the physiological effect of vibration DOI: /IJRTER ABND 31

2 on whole body or on hand arm. Analysis of the effect of vibrations on whole body resulting from various equipments used in daily life such as lawn tractor, pick up truck and trax train is also carried out by Lowell Beck et al.[1].the research is also carried out to study the operator under varying conditions of vibration while driving a tractor with and without farm equipment on different fields by Mohammad Muzammil,FaisalHasan et. al. [2].J.Giacomin et.al.[3] investigated the human fatigue caused by automobile steering wheel vibration where discomfort data was collected from 15 subjects using a steering wheel vibration bench.studies conducted by Harrison et al. [4]have revealed that vibration level of heavy equipment such as tractor concited with the most sensitive frequencies of the body and exceeded the international standard agencies guidelines for exposure to whole body vibration.w.rohmert et al.[5] performed the experiment within the defined parameters of vibration frequency at 30 Hz, acceleration level of 40 m/s 2 and found that all the examined muscles were affected by exposure to vibration. A.K.Dasgupta et al.[6] studied the effect of vibration on the hand-arm system of miners in India. Sixty-six Jackhammer drillers and35 blasters from two mines were clinically screened for hand-arm vibration syndrome (HAVS). Prevalences of symptom complexes of 66 drillers were analyzed and the main findings suggested abnormalities in the nervous system and the musculoskeletal system rather than the peripheral circulation. Druga C. et al.[7] focused the attention on the directives of the European parliament and of the Council dated June The directive lays down minimum requirement for the protection of workers from the risk arising from vibrations. The objectives of the study made by A.G.Mayton et al. [8] were to assess driver whole body vibration exposures and recommend interventions to reduce the risk of back related injuries, particularly relative to vehicle jarring/jolting. The methodology included collecting from two independent samples, field data, health and work history data of farm equipment operators. III. PRESENT SINERIO OF VIBRATION IN INDUSTRIAL SECTOR AND ITS IMPACT Table 1 shows the type of vibration and probable sources of vibration. vibration is found in road transport and off road vehicles such as agricultural tractors, construction earth-movers, rail transport, aircraft, and industrial applications. Hand arm vibration is found in wide range of industries such as construction, forestry, foundries, building and maintenance of roads and railways etc. Table 1: Sources of vibration Type of Vibration Tractors Common Source of Vibration Heavy equipment vehicles Pneumatic tools, Jackhammers Tractors Chain saws Pneumatic chisels Vibrating hand tools Sewing machines, Looms Vehicles Vehicle operation If vibration frequencies are greater than the natural frequencies of human body part various problems such as headache, visual perception, motion sickness can be observed. During equipment operation vibration is transmitted into body and partially absorbed by the equipment operator s internal All Rights Reserved 32

3 Some health effects assumed to relate to long-term whole body vibration are: Increased risk of lumber and spine related injuries, inflammation of connective tissues of affected organs, inflammation of nervous system of affected organs, digestive system issues, genital/urinary system issues, female reproductive system issues etc. vibration affects the body of person causing pain, distress and sleep disturbance, inability to do fine work, reduced ability to work in cold and damp condition, reduced grip strength etc. Various symptoms of vibration exposure at frequencies of 1 to 20 Hz are shown in Table 2. Table No.2: Symptoms of vibration Sr. No. Symptoms Frequency 1 General feeling of discomfort Head symptoms Lower jaw symptoms Influence on speech "Lump in the throat" Chest pains Abdominal pains Urge to urinate Increased muscle tone Influence on breathing movements Muscle contractions 4-9 Figure 1shows the mechanical model of the human body with resonance frequency ranges of various body sections: Figure 1: Mechanical model of the human body Fig.1shows that legs can sustain maximum 20 Hz vibration frequency whereas lower arm upto 40 Hz and chest walls upto 100 All Rights Reserved 33

4 IV. CASE STUDY For measuring the frequencies of vibration on human body parts the experiment has been performed on three different equipments naming tractor, powered road driller and sewing machine. MMA7260Q: XYZ axis accelerometer (Electronic device) is used to measure the vibration frequency. Table 3 shows the measured and permitted vibration frequency on various body parts while operating above mentioned equipments. In the present case the vibration exposure duration has not been taken into consideration. Table 3: Measured and permitted vibration frequency on various body parts while operating tractor, powered road driller and sewing machine Equipment No.of Frequency measured in Affected body Max. sustainable observations Hz parts frequency 1 32 Legs (2-20Hz) Tractor Lower Arm (30-40 Hz) Spinal Column (10-12 Hz) 2 36 Legs (2-20Hz) Lower Arm (30-40 Hz) Spinal Column (10-12 Hz) Road Driller 1 54 Arms (30-40 Hz) Chest ( Hz) 2 58 Arms (30-40 Hz) Chest ( Hz) Sewing 1 10 Foot (2-20 Hz) Machine 2 8 Foot (2-20 Hz) While operating tractor it is observed that the whole body vibration frequency is about Hz. The body parts which are predominantly exposed are legs, spinal column, shoulder and abdominal mass. It is observed that whole body vibration frequency is 32 Hz whereas the maximum permitted frequency at legs is 20 Hz. Same way abdominal mass can sustain maximum 4-8 Hz frequency and shoulder can sustain maximum 4-5 Hz frequency. Similarly Table 3 shows that while operating road driller body is exposed to very high frequency hand-arm vibration of Hz, whereas the maximum permitted vibration frequency on shoulder is only 4-5 Hz and that on abdominal mass is 4-8 Hz only. It also shows that vibration frequency measured while operating sewing machine is 8-10 Hz. Though the frequency of vibration is not very high but it can lead to hand arm vibration and continuous work on the machine can cause headache and back pain All Rights Reserved 34

5 V. RESULTAND DISCUSSION It is observed that legs, shoulder, spinal column and abdominal mass are more prone to occupational health hazards, due to vibration for tractor operators. For road drillers shoulder, spinal column and abdominal mass are more prone to occupational health hazard due to vibration. In the same way shoulder and abdominal mass are more prone to vibration for sewing machine operator. VI. CONCLUSION The whole body vibration frequency measurement has revealed the possibility of occupational health hazard as follows:- a) Tractor operators body parts namely legs, shoulder, spinal column and abdominal mass. b) Road driller operators body parts namely shoulder, spinal column and abdominal mass. c) Sewing machine operators- body parts namely shoulder and abdominal mass. As the measured vibration frequency on above body parts is greater than the maximum permitted vibration frequency, it can cause occupational health hazards such as abdominal pains, increased muscle tone, chest pain. REFERENCES I. Lowell Beck, Donald S.et al, University of Utah, Health effects of vibrating equipment A Comparative analysis of a caterpillar cs-433bvibratory compactor II. Mohammad Muzammil,et.al, Physiological Effect of vibration on tractor drivers under variable ploughingconditions,joccup. Health 2004; 46: III. J. Giocomin et.al, (2000), Human Fatigue Due To Automobile Steering Wheel Vibration, The University of Sheffield, PP IV. J.E.Harrison and B.O.Wikstrom(1998), Comparison of some technical methods for the evaluation of whole body vibration. Ergonomics 24, V. W. Rohmert et.al, (1989), Effects of vibration on arm & shoulders, muscles In Three Body Postures, European Journal of Applied Physiology occupational Physiology, Vol 59, pp VI. A.K. Dasgupta et al, (1996), Effect Of Vibration on The Hand-Arm System Of Miners In India, Occup. Med., Vol. 46, PP VII. Druga C, Barbu D, Lache S 1 (2007)), Vibration and the human body, Annals of the Oradea UniversityFascicle of Management and Technological Engineering, Volume VI (XVI) VIII. A.G. Maytona et al, Jarring/jolting exposure and musculoskeletal symptoms among farm equipment operators,indiana State University, Terre Haute, IN, All Rights Reserved 35