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1.7.7 Appendix - contradiction matrix parameters 11-15

Aggiornamento: 8 nov 2021

11 Cushion in Advance

Prepare emergency means beforehand to compensate for the relatively low reliability of an object ( ‘ belt and braces ’ )

■ Multi-channel control system

■ Air-bag in a car /Spare wheel/Battery back - up/Back - up parachute

■ Pressure relief valve

■ Emergency lighting circuit

■ Automatic save operations performed by computer programs

■ Crash barriers on motorways

■ ‘ Touch - down ’ bearing in magnetic bearing system

12 Equipotentiality

If an object has to be raised or lowered, redesign the object’s environment so the need to raise or lower is eliminated or performed by the environment

■ Canal locks

■ Spring loaded parts delivery system in a factory

■ Mechanic’s pit in a garage means car does not have to be lifted

■ Place a heavy object on ice, and let ice melt in order to lower it

■ Angle - poise lamp; changes in gravitational potential stored in springs

■ Descending cable cars balance the weight of ascending cars

13 The Other Way Around

A. Invert the action used to solve the problem, (e.g. instead of cooling an object, heat it)

■ To loosen stuck parts, cool the inner part instead of heating the outer part

■ Vacuum casting

■ Rotary engines

■ Test pressure vessel by varying pressure outside rather than inside

■ Test seal on a liquid container by fi ling with pressurised air and immersing in liquid; trails of bubbles are easier to trace than slow liquid leaks

■ Unstick frozen articles from each other by making them colder (rather than defrost)

B. Make movable parts (or the external environment) fixed, and fixed parts movable

■ Hamster wheel

■ Rowing jogging machines

■ Rotate the part instead of the tool

■ Wind tunnels

■ Moving sidewalk with standing people

■ Drive through restaurant or bank

C. Turn the object (or process) ‘ upside down ’

■ Tomato sauce bottle

■ Clean bottles by inverting and injecting water from below

■ Turn an assembly upside down to insert fasteners

■ Garage pit

14 Spheroidality Curvature

A. Move from flat surfaces to spherical ones and from parts shaped as a cube (parallelepiped) to ball - shaped structures

■ Use arches and domes for strength in architecture

■ Introduce fillet radii between surfaces at different angles

■ Introduce stress relieving holes at the ends of slots

■ Change curvature on lens to alter light deflection properties

B. Use rollers, balls, spirals

■ Spiral gear (Nautilus) produces continuous resistance for weight lifting

■ Ball point and roller point pens for smooth ink distribution

■ Use spherical casters instead of cylindrical wheels to move furniture

■ Archimedes screw

C. Go from linear to rotary motion (or vice versa)

■ Rotary actuators in hydraulic system

■ Switch from reciprocating to rotary pump

■ Push/pull versus rotary switches (e.g. lighting dimmer switch)

■ Linear motors

■ Linear versus rotating tracking arm on a record turntable ensures constant angle of stylus relative to groove

■ Screw - thread versus nail

D. Use centrifugal forces

■ Centrifugal casting for even wall thickness structures

■ Spin components after painting to remove excess paint

■ Remove water from clothes with a spin dryer rather than a mangle

■ Separate chemicals with different density properties using a centrifuge

■ Watt governor

■ Vortex/cyclone separates different density objects

15 Dynamics

A. Change the object (or outside environment) for optimal performance at every stage of operation

■ Foam or Shape changing mattress

■ Gel fillings inside seat allow it to adapt to user

■ Adjustable steering wheel (or seat, or back support, or mirror position … )

■ Shape memory alloys/polymers

■ Racing car suspension adjustable for different tracks and driving techniques

■ Car handbrake adjustable to account for brake pad wear

■ Telescopic curtain rail – “ one size fi ts all ”

■ Easy to thread needle – eye opens for threading and closes again for use

B. Divide an object into parts capable of movement relative to each other

■ Bifurcated bicycle saddle

■ Articulated lorry

■ Folding chair/mobile phone/laptop/etc

■ Collapsible structures

■ Brush seals

C. Change from immobile to mobile

■ Bendy drinking straw

■ Flexible joint

■ Collapsible hose is flexible in use, and has additional flexibility of cross - section to make it easier to store

D. Increase the degree of free motion

■ Use of different stiffness fibres in toothbrush – easily defl ected at the edges to prevent gum damage, hard in the middle

■ Flexible drive allows motion to be translated around bends

■ Loose sand inside truck tyre gives it self - balancing properties at speed

■ Add joints to robot arm to increase motion possibilities


TRIZ for Engineers: Enabling Inventive Problem Solving, First Edition. Karen Gadd.

© 2011 John Wiley & Sons, Ltd. Published 2011 by John Wiley & Sons, Ltd. ISBN: 978-0-470-74188-7

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