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Elementary Ergonomics Short Introduction to Biomechanics
Richard Goossens
EE, 25 Nov 2013
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Biomechanics Forces in and on body
Question 1: What forces act on us?
Question 2: How to design for it?
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Forces
Atmosphere
10 N/cm2
Gravity
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Zero gravity
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Zero gravity
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Problems
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Free body diagram
Cut loose
F, M
Equilibrium?
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Pressure
Gravity on surface
Stand up
Body 75 kg, feet 150 cm2 ≈ 2.5 N/cm2
Sit down
60% body, seat surface 1000 cm2 ≈ 0.5 N/cm2
Not uniformly distributed: 1- 2 N/cm2
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Aspects of comfortcapillarvessels
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What is maximum allowable pressure on skin?
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Time?
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Shear
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Deformation
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Human Pressure and Shear sensors
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Innovations
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Rule of thumb angles/forces/pressure
Comfort about 30% max
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Backrest needed?
B C
Back rest
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Muscle-length
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1500 N
Static
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Dynamic
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Force
Stay below 15% max
10% max (static)
How to determine max?
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Max?
Use existing data and rules of thumb
Woman = 30% less force than man
Elderly and child: 30% van 20-40 man/woman
P5 about 30% P50
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Exercise
Free body diagram
Estimate weight that can be hold all day
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End of this presentation
Thank you for your attention