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Vibration
Sean Mahar, PhD, CIH, CSP, PESean Mahar, PhD, CIH, CSP, PE
Vibration Vibration IntroductionIntroduction
• TypesTypes
• ProblemsProblems
• ControlsControls
• MeasurementsMeasurements
• StandardsStandards
Sean MaharSean Mahar
• BS, Sacred Heart UniversityBS, Sacred Heart University
• MS, Texas A&M UniversityMS, Texas A&M University
• PhD, University of IowaPhD, University of Iowa
• Certified Industrial HygienistCertified Industrial Hygienist
• Certified Safety ProfessionalCertified Safety Professional
• Professional EngineerProfessional Engineer
ExperienceExperience
• U of Wolverhampton, 4 yearsU of Wolverhampton, 4 years
• Ohio University, 3 yearsOhio University, 3 years
• Worksafe Iowa, 3 yearsWorksafe Iowa, 3 years
• US Navy, 9 yearsUS Navy, 9 years
• Tracor, 1 yearTracor, 1 year
Educational ObjectiveEducational Objective
The student should have a basic The student should have a basic understanding of the measurement and understanding of the measurement and control of vibration, including what control of vibration, including what instruments are used, the relevant instruments are used, the relevant exposure limits, but they need not have exposure limits, but they need not have the practical experience to enable them the practical experience to enable them to carry out a vibrations survey.to carry out a vibrations survey.
Definitions and measurements unitsDefinitions and measurements units
Units of measurement - understanding of Units of measurement - understanding of acceleration amplitudeacceleration amplitude
Velocity amplitude displacement Velocity amplitude displacement amplitude amplitude
Definitions and measurements unitsDefinitions and measurements units
Choice of measurement parameters, Choice of measurement parameters, dynamic range and frequency dynamic range and frequency information requiredinformation required
Relationship and implications of mass Relationship and implications of mass and stiffness and damping, natural and stiffness and damping, natural frequency and static deflectionfrequency and static deflection
Monitoring instrumentsMonitoring instruments
Vibration transducersVibration transducersPiezoelectric accelerometer. Also aware of Piezoelectric accelerometer. Also aware of
existence of proximity probes and velocity pick-existence of proximity probes and velocity pick-up.up.
MetersMetersElements of a general purpose vibration Elements of a general purpose vibration
meter.Also awareness of swept filter frequency meter.Also awareness of swept filter frequency analyser and fast Fourier transformanalyser and fast Fourier transform analyser.analyser.
Making a surveyMaking a survey
ISO Evaluation of human exposure to ISO Evaluation of human exposure to whole body vibrationwhole body vibration::
• Equivalent acceleration valueEquivalent acceleration value• Frequencies of the vibrationFrequencies of the vibration• Direction of excitement of the vibrationDirection of excitement of the vibration• Time of exposure to vibrationTime of exposure to vibration
Making a surveyMaking a survey
ISO Guidelines for the assessment of ISO Guidelines for the assessment of human exposure to hand-arm human exposure to hand-arm vibrationvibration::
• Frequency weighted RMS acceleration Frequency weighted RMS acceleration valuevalue
• Probability of developing white finger Probability of developing white finger syndromesyndrome
Exposure limits for vibrationExposure limits for vibration
• ISO 2631:1997ISO 2631:1997 Guide for the evaGuide for the eval. l. of of human exposure to whole body human exposure to whole body vibration. vibration.
• ISO 5349-1:2001 Guide to measISO 5349-1:2001 Guide to meas,, and and evaeval.l. of human exposure to vibration of human exposure to vibration transmitted to the handtransmitted to the hand
• HSG 88HSG 88 Hand -arm vibrationHand -arm vibration
Control of vibrationControl of vibration
Whole-body vibration dampingWhole-body vibration damping
• Use of suspension system for vehiclesUse of suspension system for vehicles• Use of suspension system for seats of Use of suspension system for seats of
vehicles with stiff suspensionsvehicles with stiff suspensions• Decrease operator's exposure time by Decrease operator's exposure time by
job rotatingjob rotating
Control of vibrationControl of vibration
Hand-arm vibration dampingHand-arm vibration damping
• Damping of tool internallyDamping of tool internally• Insertion of damping between tool Insertion of damping between tool
housing and handhousing and hand• Remote operation of toolRemote operation of tool• Decreasing operator's exposure by job Decreasing operator's exposure by job
rotationrotation
Vibration effects and limitsVibration effects and limits
Health effects of whole body vibration, Health effects of whole body vibration, vibration dosevibration dose
Sensitivity to vibration at different Sensitivity to vibration at different frequencies,frequencies,
Fatigue - decreased proficiency and Fatigue - decreased proficiency and exposure limits, reduced comfort exposure limits, reduced comfort
Vibration effects and limitsVibration effects and limits
Sources of vibrationSources of vibration
Vibration in buildings, Vibration in buildings,
Segmental vibration, hand arm vibration Segmental vibration, hand arm vibration - neurological and vascular effects- neurological and vascular effects
Vibration from powered hand tools and Vibration from powered hand tools and other processesother processes
Vibration effects and limitsVibration effects and limits
8-hour energy equivalent weighted 8-hour energy equivalent weighted acceleration acceleration
Relationship between time to Relationship between time to development of vascular symptoms development of vascular symptoms and weighted vibration and exposure and weighted vibration and exposure timetime
Vibration effects and limitsVibration effects and limits
BSEN ISO 2631 4:2001 BSEN ISO 2631 4:2001
Fatigue - decreased proficiency and Fatigue - decreased proficiency and exposure limits, reduced comfort exposure limits, reduced comfort
BS 6472 1992BS 6472 1992
Vibration in buildings, 1-80 HzVibration in buildings, 1-80 Hz
VibrationVibration
• oscillatory oscillatory motionmotion of a of a systemsystem
VibrationVibration
• oscillatory oscillatory motionmotion of a of a systemsystem
motionmotion - simple harmonic or otherwise - simple harmonic or otherwise systemsystem - gaseous, liquid, or solid - gaseous, liquid, or solid
air molecules vibrating 20 - 20,000 Hz air molecules vibrating 20 - 20,000 Hz is soundis sound
VibrationVibration
Vibration Parameters
• DisplacementDisplacement
• FrequencyFrequency
• VelocityVelocity
• AccelerationAcceleration
DisplacementDisplacement
x(t)x(t) = = XX sin (2 sin (2 t/T) t/T) = X= X sin sin t t
= = XX sin (2 sin (2 f t) f t)
xx = instantaneous displacement = instantaneous displacement (m) (m)
XX = maximum displacement = maximum displacement (m) (m)
t = timet = time (s), (s), T = period of vibrationT = period of vibration (s) (s)
f = frequency of vibrationf = frequency of vibration (Hz) (Hz)
= angular frequency (2 = angular frequency (2 f ) f ) (radians/s) (radians/s)
VelocityVelocity
v = dx/dt = v = dx/dt = X cos (X cos (t) =t) =
= V cos (= V cos (T) = V sin (T) = V sin ( + + /2)/2)
= V cos (2 = V cos (2 f t)f t)
v = instantaneous velocityv = instantaneous velocity (m/s) (m/s)
V = maximum velocityV = maximum velocity (m/s) (m/s)
AccelerationAcceleration
a = dv/dt = d²x/dt² = - a = dv/dt = d²x/dt² = - ²S sin (²S sin (t) t)
= - A sin (= - A sin (t + t + ) )
= - A sin (2 = - A sin (2 f t)f t)
a = instantaneous acceleration (m/sa = instantaneous acceleration (m/s22))
A = maximum acceleration (m/sA = maximum acceleration (m/s22))
Acceleration, rmsAcceleration, rms
)(1
= T
0)( dtta
Ta
2rms
Acceleration, rmsAcceleration, rms
2)(
2)(
2)()xyz( = rmszrmsyrmsxrms aaaa
Crest factorCrest factor
rms
peak =factor crest
Phase DifferencePhase Difference
Non-harmonic motionNon-harmonic motion
Non-harmonic motionNon-harmonic motion
Effects depend on:Effects depend on:
• frequency (Hz)frequency (Hz)• displacement (m)displacement (m)• accelerationacceleration (m/s(m/s22)) - a measure of the - a measure of the
intensityintensity• resonanceresonance - depends upon the natural - depends upon the natural
resonant frequency of either the source of resonant frequency of either the source of vibration or of the object being vibrated (the vibration or of the object being vibrated (the human body segments or organs).human body segments or organs).
VibrationVibration
Segmental or Hand-Arm VibrationSegmental or Hand-Arm Vibration
General or Whole Body VibrationGeneral or Whole Body Vibration
Segmental or Hand-Arm VibrationSegmental or Hand-Arm Vibration
Transmitted to handsTransmitted to hands
and arms from powerand arms from power
tools and other tools and other
vibrating equipment, vibrating equipment,
such as chain saws, such as chain saws,
chipping tools, drills, chipping tools, drills,
grinders, motor bikes.grinders, motor bikes.
General or Whole Body VibrationGeneral or Whole Body Vibration
Transmitted to theTransmitted to the
sitting or standing bodysitting or standing body
through transmittingthrough transmitting
surfaces such as insurfaces such as in
aircraft, ships,aircraft, ships,
vehicles or working onvehicles or working on
vibrating floors.vibrating floors.
Segmental VibrationSegmental Vibration
SymptomsSymptoms
• finger blanching, particularly when finger blanching, particularly when exposed to the coldexposed to the cold
• tingling and loss of sensation in fingerstingling and loss of sensation in fingers
• loss of light touch (difficulty fastening loss of light touch (difficulty fastening buttons and zippers)buttons and zippers)
• pain and cold sensations between pain and cold sensations between periodic white finger attackperiodic white finger attack
SymptomsSymptoms
• loss of grip strengthloss of grip strength
• bone cysts in fingers and wristsbone cysts in fingers and wrists
• carpal tunnel syndromecarpal tunnel syndrome
Although segmental or local vibration Although segmental or local vibration almost always affects only upper limbs, legs almost always affects only upper limbs, legs can be affected if they come into contact can be affected if they come into contact with vibrating equipment. with vibrating equipment.
Primary syndrome namesPrimary syndrome names
• Raynaud's syndromeRaynaud's syndrome
• Traumatic Vasospastic DiseaseTraumatic Vasospastic Disease
• Vibration White FingerVibration White Finger
• Hand Arm Vibration SyndromeHand Arm Vibration Syndrome
CharacteristicsCharacteristics
• sudden block in blood circulation to sudden block in blood circulation to fingersfingers
• fingers become white, pale, cold, and fingers become white, pale, cold, and sometimes painfulsometimes painful
• tactile sensitivity reducedtactile sensitivity reduced
• Symptoms last from minutes to Symptoms last from minutes to hours, at first reversiblehours, at first reversible
www.whitefinger.co.ukwww.whitefinger.co.uk
CausesCauses
• vascular disturbance vascular disturbance
– (changes in blood vessel walls) (changes in blood vessel walls)
• nervous disturbance nervous disturbance
– (reflex contraction of smooth muscles (reflex contraction of smooth muscles of blood vessels) of blood vessels)
• occurs naturally in ~ 1% of pop, 90% of occurs naturally in ~ 1% of pop, 90% of which are femalewhich are female
FactorsFactors
• PhysicalPhysical
• BiodynamicBiodynamic
• IndividualIndividual
Physical FactorsPhysical Factors
• Dominant frequencies & vibration Dominant frequencies & vibration directiondirection
• Years of employment & daily durationYears of employment & daily duration
• Temporal exposure patternTemporal exposure pattern
• Non-occupational exposureNon-occupational exposure
Biodynamic FactorsBiodynamic Factors
• Grip forcesGrip forces
• Surface area & mass of handSurface area & mass of hand
• Handle orientation & textureHandle orientation & texture
Individual FactorsIndividual Factors
• SusceptibilitySusceptibility
• Vasoconstrictive agents Vasoconstrictive agents – (smoking, drugs) (smoking, drugs)
Frequency Weighting Curve
0.01
0.10
1.00
1.0 10.0 100.0 1000.0
Frequency, HZ
We
igh
tin
g F
ac
tor
Frequency dependenceFrequency dependence
Taylor-Pelmear Taylor-Pelmear CClassificatiolassificationn
StageStage Signs andSigns and
symptomssymptoms
InterferenceInterference
wwith activitiesith activities00 NoneNone NoneNone
0T0T Intermittent Intermittent tinglingtingling
NoneNone
0N0N Intermittent Intermittent numbnessnumbness
NoneNone
0TN0TN Tingling and Tingling and numbnessnumbness
NoneNone
Taylor-Pelmear Taylor-Pelmear CClassificatiolassificationn
StageStage Signs andSigns and
symptomssymptoms
InterferenceInterference
wwith activitiesith activities11 Blanching of one Blanching of one
or more fingertips or more fingertips wwith or without ith or without tingling and tingling and numbnessnumbness
NoneNone
Taylor-Pelmear Taylor-Pelmear CClassificatiolassificationn
StageStage Signs andSigns and
symptomssymptoms
InterferenceInterference
wwith activitiesith activities22 Blanching of one Blanching of one
or more fingers or more fingers with numbness, with numbness, usually during usually during winter onlywinter only
Slight interference with Slight interference with home and social home and social activities; no activities; no interference with workinterference with work
Taylor-Pelmear Taylor-Pelmear CClassificatiolassificationn
StageStage Signs andSigns and
symptomssymptoms
InterferenceInterference
wwith activitiesith activities33 Extensive Extensive
blanching with blanching with frequent episodes frequent episodes during both during both summer and summer and winterwinter
Definite interference Definite interference with work, home, and with work, home, and social activities;social activities;restricted hobbiesrestricted hobbies
Taylor-Pelmear Taylor-Pelmear CClassificatiolassificationn
StageStage Signs andSigns and
symptomssymptoms
InterferenceInterference
wwith activitiesith activities44 Extensive Extensive
blanching of most blanching of most fingers; frequent fingers; frequent episodes during episodes during summer and summer and winter; finger winter; finger ulcerationulceration
Occupation change Occupation change required to avoid required to avoid further vibration further vibration exposureexposure
Stockholm scale for vascular symptoms
StageStage DescriptionDescription
00 NNo attackso attacks
11 Occasional attacks that affect only the Occasional attacks that affect only the tips of one or more fingerstips of one or more fingers
22 Occasional attacks that affect the distal Occasional attacks that affect the distal and middle (rarely also proximal) and middle (rarely also proximal) phalanges of one or more fingersphalanges of one or more fingers
Stockholm scale for vascular symptoms
StageStage DescriptionDescription
33 Frequent attacks affecting all phalanges Frequent attacks affecting all phalanges of most fingersof most fingers
44 As in stage 3, with trophic skin changes As in stage 3, with trophic skin changes in the finger tipsin the finger tips
Stockholm scale for sensorineural stages
StageStage DescriptionDescription
0SN0SN Exposed to vibration but no symptomsExposed to vibration but no symptoms
1SN1SN Intermittent numbness, with or without Intermittent numbness, with or without tinglingtingling
2SN2SN Intermittent or persistent numbness, Intermittent or persistent numbness, reduced sensory perceptionreduced sensory perception
3SN3SN Intermittent or persistent numbness, Intermittent or persistent numbness, reduced tactile discrimination and/or reduced tactile discrimination and/or manipulative dexteritymanipulative dexterity
ControlControl
Control MeasuresControl Measures
• Anti-vibration tools Anti-vibration tools
• Anti-vibration glovesAnti-vibration gloves
• Safe work practicesSafe work practices
• Warm clothing, including glovesWarm clothing, including gloves
• Avoid holding the tool too tightly Avoid holding the tool too tightly
Control MeasuresControl Measures
• Regular rest breaksRegular rest breaks
• Rest the toolRest the tool
• Regular equipment maintenanceRegular equipment maintenance
– eg keeping cutting tools sharpeg keeping cutting tools sharp
• Reduce smokingReduce smoking
Whole Body VibrationWhole Body Vibration
Whole Body VibrationWhole Body Vibration
Vibration energy Vibration energy absorbed by absorbed by body tissue and body tissue and organs.organs.
Whole Body VibrationWhole Body Vibration
• Spinal column diseaseSpinal column disease• Digestive system problemsDigestive system problems• Cardiovascular effectsCardiovascular effects• Motion sicknessMotion sickness• DiscomfortDiscomfort• Loss of balance and concentrationLoss of balance and concentration• FatigueFatigue
Whole Body VibrationWhole Body Vibration
• Energy absorbed by Energy absorbed by body tissue and organsbody tissue and organs muscles esp. important muscles esp. important
• Leads to Leads to
voluntary/involuntary voluntary/involuntary contraction contraction causing fatiguecausing fatigue
esp. at resonant frequency esp. at resonant frequency
Whole Body VibrationWhole Body Vibration
• Reflex contractions Reflex contractions reduce motor capabilities.reduce motor capabilities.increase risk of low back painincrease risk of low back paineg- tractor, truck and bus drivers,eg- tractor, truck and bus drivers,
• some studies have even shown some studies have even shown radiographic changesradiographic changes
Whole Body VibrationWhole Body Vibration
• extremely extremely strong vertical strong vertical accelerations accelerations can cause spinal can cause spinal fractures fractures (compression)(compression)
ResonanceResonance
• 5-10 Hz range: 5-10 Hz range: thoracic-abdominal systemthoracic-abdominal system
• 20-30 Hz range: 20-30 Hz range: head-neck-shoulder systemhead-neck-shoulder system
• 60-90 Hz range: 60-90 Hz range: eyeballeyeball
Very low-frequency 0.1 - 1 HzVery low-frequency 0.1 - 1 Hz
• Cause motion sickness by upsetting the Cause motion sickness by upsetting the body's balance mechanism.body's balance mechanism.
• Motion sickness appears to be worst at Motion sickness appears to be worst at about 0.3 Hzabout 0.3 Hz
• If pitch and roll are present as well as If pitch and roll are present as well as vertical displacement, tolerance to the vertical displacement, tolerance to the vibration is loweredvibration is lowered
Low-frequency 1 - 80 HzLow-frequency 1 - 80 Hz
• Short term (acute effects):Short term (acute effects):
– fatigue, insomnia, headache and fatigue, insomnia, headache and "shakiness""shakiness"
• Long term (chronic effects):Long term (chronic effects):
– circulatory, bowel, respiratory, muscular circulatory, bowel, respiratory, muscular and back disordersand back disorders
– Vibration, lifestyle, and posture Vibration, lifestyle, and posture contributecontribute
Frequency Weighting Curve
-55.0
-45.0
-35.0
-25.0
-15.0
-5.0
5.0
0.1 1.0 10.0 100.0 1000.0
Frequency, Hz
We
ight
ing
, dB
Frequency dependenceFrequency dependence
ControlControl
Control MeasuresControl Measures
• Move machine controls away from vibrating Move machine controls away from vibrating surfacessurfaces
• Mechanically isolate the vibrating sourceMechanically isolate the vibrating source
• Maintain vibrating machineryMaintain vibrating machinery
• Reduce exposure timeReduce exposure time
Much of these efforts will also reduce noise Much of these efforts will also reduce noise exposure exposure
AssessmentAssessment
AssessmentAssessment
• Vibration magnitudeVibration magnitude
• Daily exposure timeDaily exposure time
• Partial exposurePartial exposure
• 8 hour exposure8 hour exposure
Vibration AssessmentVibration Assessment
• Manufacturer’s dataManufacturer’s data
• National Institute for Working LifeNational Institute for Working Life– http://umetech.niwl.se/Vibration/http://umetech.niwl.se/Vibration/
• MeasurementsMeasurements
MeasurementMeasurement
Vibration Pick-upVibration Pick-up
• MeasuresMeasures– DisplacementDisplacement– VelocityVelocity– AccelerationAcceleration
• Accelerometer normally usedAccelerometer normally used– Parameters inter-relatedParameters inter-related
AccelerometerAccelerometer
• Electromechanical transducerElectromechanical transducer
• PiezoelectricPiezoelectric
• PiezioresistivePiezioresistive
AccelerometerAccelerometer
• PiezoelectricPiezoelectric– Two piezoelectric discs produce a Two piezoelectric discs produce a
voltage on their surfaces due to a voltage on their surfaces due to a mechanical strain on asymmetric mechanical strain on asymmetric crystalscrystals
– Robust and sensitiveRobust and sensitive
MeasurementMeasurement
AccelerometerAccelerometer
Frequency analyserFrequency analyser
Pre-amplifierPre-amplifier Level recorderLevel recorder
MeasurementMeasurement
Axis of VibrationAxis of Vibration
Accelerator MountingAccelerator Mounting
• Good frequency Good frequency responseresponse
• Not affected by Not affected by surface surface temperaturetemperature
• Contact surface Contact surface must be flatmust be flat
• Difficult to use on Difficult to use on hand toolshand tools
Accelerator MountingAccelerator Mounting
• Good frequency Good frequency response response
• Contact surface Contact surface must be flat and must be flat and cleanclean
Accelerator MountingAccelerator Mounting
• Rapid mountingRapid mounting
• Suitable for triaxial Suitable for triaxial measurementsmeasurements
• LightLight
• No sharp edgesNo sharp edges
• Mainly limited to Mainly limited to measurement on measurement on power tool handlespower tool handles
Accelerator MountingAccelerator Mounting
• Can be used in Can be used in cases where a fixed cases where a fixed coupling is coupling is inapplicable, e.g. on inapplicable, e.g. on soft or resilient soft or resilient materialsmaterials
• Only suitable for Only suitable for fixed hand position fixed hand position and where the and where the handle is always handle is always being heldbeing held
Accelerator MountingAccelerator Mounting
• The presence of the The presence of the adaptor may adaptor may change tool change tool operation and the operation and the vibration magnitudevibration magnitude
• Additional fixing Additional fixing (e.g. adhesive) is (e.g. adhesive) is required for required for transverse transverse measurementsmeasurements
Accelerometer placementAccelerometer placement
Accelerometer placementAccelerometer placement
Accelerometer placementAccelerometer placement
Accelerometer placementAccelerometer placement
Single tool, 8 hour TWASingle tool, 8 hour TWA
88 usedta)A(
Multiple toolsMultiple tools
222
21 8...888 )(A)(A)(A)A( i
HAVS Exposure limitsHAVS Exposure limits
HSE Action Level Recommendation:HSE Action Level Recommendation:
2.8 m/s2.8 m/s22 A(8) A(8)
Physical Agents Directive:Physical Agents Directive:
Exposure Action Value (EAV):Exposure Action Value (EAV):
2.5 m/s2.5 m/s22 A(8) A(8)
Exposure Limit Value (ELV):Exposure Limit Value (ELV):
5.0 m/s5.0 m/s22 A(8) A(8)
HAVS Exposure limitsHAVS Exposure limits
HSE Action Level Recommendation:HSE Action Level Recommendation:
2.8 m/s2.8 m/s22 A(8) A(8)
• Based on magnitude of vibration in the Based on magnitude of vibration in the dominant axisdominant axis
• Basing it on total value increases value Basing it on total value increases value by a factor of 1.4 on average to: by a factor of 1.4 on average to:
4 m/s4 m/s22 A(8) A(8)
Exposure equivalentsExposure equivalents
Total exposure Total exposure duration (hours)duration (hours)
1616 88 44 22 11 ½½
Average (rms) Average (rms) vibration vibration magnitude (m/smagnitude (m/s22) ) to give to give daily exposure of daily exposure of 2.5 (m/s2.5 (m/s22) A(8)) A(8)
1.81.8 2.52.5 3.53.5 55 77 1010
Exposure equivalentsExposure equivalents
Total exposure Total exposure duration (hours)duration (hours)
1616 88 44 22 11 ½½
Average (rms) Average (rms) vibration vibration magnitude (m/smagnitude (m/s22) ) to give to give daily exposure of daily exposure of 5.0 (m/s5.0 (m/s22) A(8)) A(8)
3.53.5 5.05.0 77 1010 1414 2020
Whole Body Exposure limitsWhole Body Exposure limits
Root Mean Square (RMS) or A8 methodRoot Mean Square (RMS) or A8 method
Vibration Dose Value Method (VDV)Vibration Dose Value Method (VDV)
Root Mean Square (RMS) or A8 Root Mean Square (RMS) or A8 methodmethod
Uses units of metres per second squared Uses units of metres per second squared normalised to 8 hours [m/snormalised to 8 hours [m/s22A(8)] A(8)] or A(8) or A(8)
Produces a cumulative exposure using an Produces a cumulative exposure using an average acceleration adjusted to average acceleration adjusted to represent an 8 hour working dayrepresent an 8 hour working day
Vibration Dose Value Method Vibration Dose Value Method (VDV)(VDV)
Ues metres per second to the power of Ues metres per second to the power of 1.75 and is known as Vibration 1.75 and is known as Vibration Dose Value or VDV Dose Value or VDV
Sensitive to individual high acceleration Sensitive to individual high acceleration events and produces a cumulative events and produces a cumulative dose over a (working) day.dose over a (working) day.
Whole Body Exposure limitsWhole Body Exposure limits
Root Mean Square (RMS) or A8 methodRoot Mean Square (RMS) or A8 method• EAV 0.5 m/sEAV 0.5 m/s22, ELV 1.15 m/s, ELV 1.15 m/s22
Vibration Dose Value Method (VDV)Vibration Dose Value Method (VDV)• EAV 9.1 m/sEAV 9.1 m/s1.751.75 , ELV 21 m/s , ELV 21 m/s1.751.75