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ISE 3624 > Industrial Ergonomics Unit 1 > Flashcards

Industrial Ergonomics Unit 1 Flashcards

1
Q

What is Ergonomics?

A

Is the process of designing or evaluating products, tasks, environments, and systems to improve performance and/or reduce the risk of injury.

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2
Q

Acute or Chronic Musculoskeletal Disorders (MSDs)

A

Present in 12% of Population
32 million MS injuries per year
Nearly 2% of workers have work-related back problems each year
National systems markedly underestimate magnitudes

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3
Q

Cost of MSDs

A

The total cost of occupational injuries and illness in the US is >$150 Billion (nearly 3% of GDP)
More than AIDS, nearly equal to costs of cancer or heart disease
Injuries account for 85% of these costs, with MS injuries generating a large majority
Work-related MSDs account for ~1/3 of all workers compensation costs

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4
Q

Types of Physical Ergonomics Problems

A

Anthropometric problems
Musculoskeletal problems
Metabolic/Cardiovascular problems
Environmental problems

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5
Q

The Ergonomic Process

A
  1. Characterize existing or potential problems
  2. Perform job analysis
  3. Implement controls
  4. Evaluate the effectiveness of controls, and educate employees on ergonomics
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6
Q

Guiding Principle of Ergonomics

A

D (Demands) < C (Capacity or Capability)

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7
Q

6 Types of Interactions

A 
Human with Machine
Machine with Human
Human with Environment
Environment with Human
Machine with Environment
Environment with Machine
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8
Q

Stress Formula

A

Stress = Force/ Initial cross-sectional area

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9
Q

Strain Formula

A

Strain = Change in length/ Original length

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10
Q

Mechanical properties of bone

A
  1. Hooke’s law
  2. Young’s modulus (E)
  3. Yield stress
  4. Yield strain
  5. Ultimate stress
  6. Ultimate strain
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11
Q

Wolff’s Law

A

Bone (or other material) adapts to its mechanical environment: it will be added where needed and reabsorbed where not needed

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12
Q

Ligaments

A

Ligaments connect bone to bone

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13
Q

Tendons

A

Tendons connect muscles to bones

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14
Q

Structural differences between ligaments and tendons

A

Tendon fibers are parallel to one another due to the push and pull function of a tendon, while ligaments fibers are cross-sectional due to the variety of ways a ligament is pulled.

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15
Q

Cartilage

A

A smooth elastic tissue that covers the ends of long bones at joints to provide a low-friction for movement.

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16
Q

Fascia

A

A band or sheet of connective tissue, primarily collagen, beneath the skin that attaches, stabilizes, encloses, and separates muscles and other internal organs.

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17
Q

Viscoelasticity

A

Material response to force (or displacement) depends not only on force (or displacement), but also on time.

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18
Q

Creep

A

A change in strain for constant stress, and over time will reach a constant displacement

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19
Q

Load (stress) relaxation

A

A change in stress for constant strain, and over time will reach a constant force

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20
Q

Muscle Structure Units

A

(Largest) Muscle -> Fascicle -> muscle fiber -> myofilament (Smallest)

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21
Q

Myofilaments

A

Thin (actin) filaments

Thick (myosin) filaments

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22
Q

How does a muscle contract

A

Muscles contract not because of shortening of individual myofilaments, but because they slide

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23
Q

Types of muscle contractions

A

Isometric- constant length (or joint angle)
Concentric- muscle shortening
Eccentric- muscle lengthening,&raquo_space;> external load (plyometric)
Isokinetic- constant velocity (or joint angular velocity)
Isotonic- constant force (or moment)

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24
Q

Muscle groupings

A

Co-contraction- two or more muscles contracting at the same time
Agonist- contributes to the desired effort
Antagonist- opposes desired effort

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25
Q

Force-length Relationship

A

The amount of force a muscle can produce depends upon its length. Muscle force also depends upon passive tension

26
Q

Force-Velocity Relationship

A

The amount of force a muscle can produce depends upon its velocity (rate of change of length)

27
Q

Force-Activation Relationship

A

The amount of force a muscle produces depends upon its activation level (0-100%)

28
Q

The Motor Unit

A

A single nerve and all of the muscle fibers it innervates

29
Q

3 Types of Muscle Fibers

A

Slow (Type I) and fast (Type IIaand Type IIb ) fibers

30
Q

Muscle Spindles

A

Are specialized muscle fibers that provide CNS feedback on muscle strain (length) and strain rate (velocity)

31
Q

Golgi Tendon Organs

A

Golgi tendon organs provide CNS feedback on muscle force. Oriented in series with muscle, act as a force gauge

32
Q

WMSDs

A

Work tasks and environment contribute significantly to the condition, and likely make it worse or persist longer
Involve injury to soft tissues of the body and joints
They develop gradually over time
The injury event, or the exposure leading to the event, involves bodily action, overexertion, or repetitive motion.
WMSDs do not include sudden injuries such as those from slips, trips, and falls, or motor vehicle accidents

33
Q

What is a risk factor?

A

A risk factor is an individual characteristic or exposure associated with an increased risk of a disease or injury.

34
Q

Individual risk factors for WMSDs

A 
Age
Sex
Obesity (anthropometry)
Systemic diseases (e.g. diabetes)
Acute trauma
Congenital conditions
35
Q

Task-related risk factors for WMSDs

A 
High force exertions
Highly repetitive work or static work
Awkward or extreme postures
Vibration
Contact mechanical stress
Environmental stress
36
Q

Psychosocial risk factors for WMSDs

A 
Psychological factors (individual-level) and social factors (organization-level) that influence the mental state of the individual 
Examples: mental stress, supervisory control, autonomy, job security, interaction with coworkers, anxiety, etc.
37
Q

Tendon Disorders

A

Tendonitis: Inflammation of the tendon
Tenosynovitis: Inflammation of tendon sheath

38
Q

Hierarchy of Controls

A

Elimination, Substitution, Engineering Controls, Administrative Controls, PPE

39
Q

Characterize existing or potential problems

A

Quantify injuries or performances issues

Identify tasks that may have risk factors

40
Q

Evaluate the effectiveness of controls, and educate employees on ergonomics

A

Provide employees with a basic awareness of ergonomics principles.
Involve workers in the process. They have the most knowledge about their jobs. They may already know how to improve them.

41
Q

Awkward or Extreme Posture

A

Awkward posture- requires excessive effort against gravity or other issues
Extreme posture- at or near a joint’s limits of motion

42
Q

Awkward or Extreme Posture: Job Analysis

A

Determine frequency, duration, and/or magnitude of awk/extreme postures

43
Q

ErgonomicsHigh Force Exertions: Job Analysis

A

Determine frequency, duration, and/or magnitude of forceful exertions

44
Q

Contact Mechanical Stress: Job Analysis

A

Determine frequency, duration, and/or magnitude of contact force

45
Q

Anthropometry

A

Is the study of the physical dimensions of the human body

46
Q

Two types of anthropometric data

A
  1. Static anthropometry: Physical dimensions of the body

2. Functional or dynamic anthropometry: physical dimensions for completing particular activities or tasks

47
Q

Units of mass conversions (lbs)

A

1 kg = 2.2 pounds

1 slug = 32.2 pounds

48
Q

Center of mass

A

COM is the point at which all the mass of a body can be concentrated so that it results in external forces and moments equivalent to the actual distributed body

49
Q

General Design Strategies to account for anthropometric variance

A

Design for average
Design for extremes (maximum or minimum)
Design for Adjustability

50
Q

Limitations of using Anthrodata to Design

A

Population-based data can have selection bias
Averages and proportions don’t represent individuals; people are not proportional
Functional data may vary with clothing, protective equipment, etc.
Even if guidelines, standards, etc. are followed, the workstation may not be completely functional, useable, or comfortable!

51
Q

Why evaluate ROM and strength?

A

Identify high-risk work tasks
Identify high-risk workers –Workers with limited capacities may be at elevated risk for WMSD, etc.
Assess “Return to Work” status -Determine physical capacity after an injury to evaluate how much recovery has occurred.
More broadly, help improve understanding of how individual risk factors affect worker capacity

52
Q

Two types of ROM measurement

A

Active ROM: muscle force used to reach ROM limits, so also dependent upon muscle contraction
Passive ROM: external force used to reach ROM limits; more dependent upon passive elasticity of MLTs
Active ROM < Passive ROM

53
Q

Describing Joint Motions

A

Anatomical Position and Anatomical Planes of Motion

54
Q

Anatomical Terms Related to Movement

A

Flexion and extension movements occur in the sagittal plane
Abduction and adduction movements occur in the frontal plane
Rotation movements occur in the transverse plane

55
Q

Methods to measure joint ROM

A

goniometer: measures the joint angle
Inclinometer: measures the angles of slope, elevation, or depression of joint

56
Q

Individual Factors Affecting ROM

A

Age
Sex
Training
Joint or muscle pathology, genetics

57
Q

Muscle Strength

A

Defined as the maximum force/moment a group of muscles can develop under prescribed conditions

58
Q

Types of Muscle Strength Measurement

A

Isometric (static): no motion

Dynamic: strength test allowing motion

59
Q

Factors affecting strength: Posture

A

Force - length relationship
Changes in tendon moment arm with respect to the joint
Changes in weight moment arm
Two-joint muscles(muscle length depends upon two joint angles)

60
Q

Factors affecting strength: Sex

A

Women are generally weaker than men by an average of about 35% to 85%
The magnitude of sex difference is task-dependent
When corrected for muscle x-section and lean body mass, values are nearly equal!

61
Q

Factors affecting strength: Age

A

Muscle strength normally greatest in the late twenties to early thirties, and typically starts to decline in the 40s.

ISE 3624 (3 decks)

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