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Human Factors in Ergonomic Design > Biomechanics > Flashcards

Biomechanics Flashcards

1
Q

Biomechanics:

A

Uses laws of physics and engineering concepts to describe motion undergone by the various body segments and the forces acting on these parts during normal daily living

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2
Q

Occupational Biomechanics:

A

Study of the physical interaction of workers with their tools, machines and materials so as to enhance the worker’s performance while minimizing the risk of musculoskeletal disorders

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3
Q 
The goals of occupational biomechanics are to generate:
- 
- 
- 
Working conditions
A
  • tolerable
  • acceptable
  • optimal
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4
Q

Why/how is biomechanics concerned or related with ergonomics?

A

People have mechanical limitation (strength, range of motion, fatigue) and that excessive loading leads to fatigue, downtime and injuries

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5
Q

Ergonomic issues that are related to biomechanics:

A
  • awkward static postures
  • force/load
  • repetition
  • duration
  • vibration
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6
Q

Techniques of biomechanics involve kinematics and kinetics, kinematic variables are _______ and kinetic variables are ________.

A

Kinematic: time and space variables

Kinetic: force and energy variables

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7
Q

Suggestions for manual materials handling include:

A
  • Loads should be kept close to the body
  • Loads should be presented at thigh or waist height
  • Lifting should minimize twisting
  • Frequency of lifting should be minimized
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8
Q

Suggestions for seated work:

A
  • Curvature of spine should be kept

- Back support (lumbar) should be given to support the body and help keep S curve of spine

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9
Q

Common forms of cumulative trauma disorders (CTD):

A
  • Tendon-related CTD, caused by loss pf blood supply to the tendons and increased tension
  • Neuritis is damage to the nerves that can be caused by awkward posture and repeated use
  • Ischemia is the sensations of tingling and numbness, is caused by obstruction of blood flow and tissue damage
  • Bursitis is inflammation of bursa sac, which contains viscous fluid and is located between joints
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10
Q

Stress-Strain Relationships:

Stress:

Strain:

Plastic region:

Ultimate Strength:

A

Stress: applied load

Strain: deformation

Plastic Region: permanent disruption

Ultimate Strength:
Complete tear

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11
Q

Muscle fatigue:

A

Reduction in the capacity to generate force

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12
Q

Central fatigue:

A

Reduction in maximal voluntary contraction force not accompanied by same reduction in maximal evocable force

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13
Q

Excessive loads, awkward joint postures, and inadequate recovery are all possible causes for…

A

cumulative trauma disorder

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14
Q

Factors affecting performance and injury include:

A
  • individual
  • task
  • environment
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15
Q

What are the two methods of classifying and evaluating manual work:

A

Traditional and contemporary

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16
Q

Traditional methods of manual work included describing manual activities with reference to standard categories of _____ to classify and evaluate manual work.

A

Effort

17
Q

Traditional methods of classifying and evaluating manual work were based on…

A

improving efficiency without major concern for safety

18
Q

With contemporary biomechanical job analysis systems, worker is…

A

critical importance

19
Q

Physical stress checklists and surveys help to identify…

A

why the safety procedure is not being followed by employees

20
Q

1981 NIOSH Study major findings…

A

Overexertion causing low back pain (significant), overexertion injuries account for large amount of reported occupational injuries

21
Q
  • Load
  • Dimensions
  • Distribution of load
  • Couplings
  • Stability of load

These are all examples of ________ characteristics that affect ___________.

A

Material/container characteristics that affect manual material handling systems

22
Q

What are three strategies to prevent overexertion injury:

A
  1. Design the task for all workers
  2. Select workers believed to be at low risk
  3. Train workers to reduce personal risk levels

Be careful not to implement bias however!

23
Q

The 1981 NIOSH equation to evaluate sagittal plan lifting produces and objective method to determine __________

A

safe load

24
Q

To use to NIOSH equation, need to define 4 job attributes:

A
  • Location of Centre of Mass (handgrip center) of the object in horizontal direction (H)
  • Location of Centre of Mass (handgrip center) in vertical direction at start of lift
  • Vertical travel distance of the hands
  • Frequency of lifting (lifts/minute) averaged over period
25
Q

The NIOSH lifting equation is limited due to:

A
  • limited to sagittal plane
  • did not consider asymmetry
  • more consideration needed of width
  • needs consideration of quality of coupling
  • needs revision of weight limits based n frequency
26
Q

On the spine, the site of greatest stress is between:

A

L5/S1

27
Q

In 1994 the NIOSH lifting equation was revised and published, this included new biomechanical, physiological, and psychological criteria, this physiological criteria included…

A
  • Energy expenditure related to repetitive lifting
  • Large energy expenditures required to lift the body and the load
  • If lifting energy requirements exceed energy producing capacity (fatigue)
28
Q

In 1994 the NIOSH lifting equation was revised and published, this included new biomechanical, physiological, and psychological criteria, this psychological criteria included…

A
  • How much an individual will choose to lift of given the choice when lifting for an extended period of time
  • Guidelines set to meet acceptable lifting capacity of 75% of females (99% males)
29
Q

The revised NIOSH lifting equation quantifies risk when…

A
  1. Heavy objects are lifted
  2. The object is bulky
  3. The object is lifted from the floor
  4. Objects are frequently lifted
  5. Poor grips are provided
30
Q

In the NIOSH lifting equation RWL=

A

recommended weight limit

31
Q

The NIOSH liftng equation identifies the ___________ for the scenario defined in the equation

A

maximal load

32
Q

In the NIOSH lifting equation multipliers are used to…

A

adjust (reduce) the recommended load to compensate for less than optimal lifting conditions

33
Q

Lifting from the floor requires greater _______________

A

energy expenditure

34
Q

Once you calculate the RWL (recommended weight limit), calculate the LI (lift index), as actual load lifted/ RWL, LI >__ poses a significant risk to many workers, LI< __ is protective

A

LI > 3 =Risk

LI < 1 =Protective

35
Q

The limitations to the revised NIOSH lifting equation include:

A
  • Does not recognize individual risk assessment (age, sex, body weight, body type)
  • Not for use with one-handed lifting (or seated, kneeling, constrained, hot/cold environments, high-speed lifting)
  • Physiological criteria relate to whole body fatigue, not site specific (risk of injury?)
36
Q

The NIOSH lifting equation provides a quantitative starting point for comparing tasks, and links factors associated with risk of _______ in a multiplicative manner.

A

Lower back pain

37
Q

Material Handling Considerations include:

A
  • stand/sit erect
  • eliminate reaches
  • use rollers/conveyors vs. carriers/pivots
  • gravity-fed slides/shelves
  • keep it close to worker
  • tilt bins
  • allow access to all sides

Human Factors in Ergonomic Design (7 decks)

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