exam 1 Flashcards
What does “ergonomics” mean in Greek?
ergon - work
nomos - law
ergonomics
the process of designing or evaluating products, tasks, environments, and systems to improve performance and/or reduce the risk of injurt
industrial ergonomics
application of ergonomics and human factors methods to the design, evaluation, improvement of work tasks, tools, environments to improve performance, productivity, quality or decrease injury, fatigue, waste
What are side effects of ignoring ergonomics?
- compromises worker and company performance
- lower quality work and productivity
- absenteeism
- turnover
- training
- morale
- accidents
- acute of chronic musculoskeletal disorders
- occupational injuries and illnesses in the US is $150b annually
3 areas of ergonomics
- physical: human anthropometry, musculoskeletal, metabolic, cardiovascular, environmental issues; working posture, MH, repetitive movements, workplace layout, health and safety
- cognitive: mental processes as they affect interactions among humans and other elements of the system; mental workload, decision making, HCI, work stress, training
- organizational (marcoergo): sociotechnical systems, including organizational structures, policies, and processes; shift work, scheduling, job satisfaction, motivational theory, teamwork, ethics
4 types of physical ergonomics
- anthropometric: concern physical dimensional conflicts between functional space geometry and the human body
- musculoskeletal: concern forces, moments, postures, and mechanical stress on muscles and skeletal system
- metabolic/cardiovascular: concern stress on metabolic energy and cardiovascular system (heart rate, breathing rate, etc.)
- environmental: concern exposure to excessive environmental stress (heat, vibration)
What is the ergonomic process?
- characterize existing or potential problems
- perform job analysis
- implement controls
- evaluate effectiveness of controls; educate employees on ergonomics
What is the overarching goal of ergonomics?
prevent disorders through proactive design and vigilance
What is the guiding principle of ergonomics?
D = task demand C = human capability or capacity
maintain D < C
6 types of interaction
- **human with machine (H->M): control actions provided by human
- **machine with human (M->H): information feedback and forces generated by machine
- human with environment (H->E): effect of human on local environment
- **environment with human (E->H): influence of environmental factors on human performance
- machine with environment (M->E): alteration of work environment by machine
- environment with machine (E->M): machine function altered by environment
What are indicators for the need of ergonomics?
- waste production is too high
- too many rejects
- production accidents too frequent
- higher medical costs
- absenteeism is high due to injuries
- frequent complaints about job requirements
- production output or efficiency is low
5 components of the muscle system
- connective tissue: bones, ligaments, tendons, fascia, cartilage
- joints: unions with more than 1 degrees of freedom
- skeletal muscle: muscle fibers, connective tissue, nerve excitation
- nerves: afferent (sensory) and efferent (motor)
- brain: central and peripheral nervous systems
4 functions of bone
- support and motion
- protection of organs
- mineral storage (calcium and phosphorus)
- formation of blood cells
2 types of bone
- cortical (compact): dense compact shell provides strength and impact resistance; very strong
- cancellous or trabecular (spongy): organization of trabeculae tend to be distributed along lies of principal loads of stresses and strains
2 mechanical properties of bone
stress: force/initial cross-sectional area
strain: change in length/original length
What type of material is bone?
anisotropic
Wolff’s Law
bone adapts to its mechanical environment: it will be deposited where needed and be reabsorbed where not needed; bone growth stops but thickness and diameter can change
ligament
a connective tissue that binds bone to bone
tendon
a connective tissue that binds muscle to bone
cartilage
a connective tissue that is a smooth elastic tissue that covers the ends of long bones at joints to provide a low-friction surface for movement
can be a structural component
fascia
a band or sheet of connective tissue - primarily collagen - beneath the skin that attaches, stabilizes, encloses, and separates muscles and other internal organs
surrounds muscles or other structures
viscoelasticity
material response to force/displacement depends not only on force/displacement but also time
creep
change in strain for a constant stress
load (stress) relaxation
change in stress for a constant strain