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1.7.11 Appendix - contradiction matrix parameters 31- 35

Aggiornamento: 8 nov 2021

31 Porous Materials

A. Make an object porous or add porous elements (inserts, coatings, etc.)

■ Drill holes in a structure to reduce the weight

■ Cavity wall insulation

■ Transpiration film cooled structures

■ Foam metals

■ Use sponge-like structures as fluid absorption media

B. If an object is already porous, use the pores to introduce a useful substance or function

■ Use a porous metal mesh to wick excess solder away from a joint

■ Store hydrogen in the pores of a palladium sponge. (Fuel “ tank ” for the hydrogen car – much safer than storing hydrogen gas)

■ Desiccant in polystyrene packing materials

■ Medicated swabs/dressings

32 Colour Changes

A. Change the colour of an object or its external environment

■ Colour-changing paint or suncream

■ Temperature-sensitive dyes used on food product labels to indicate when desired serving temperature has been achieved

■ Electrochromic glass

■ Light-sensitive glasses

■ Camouflage

■ Employ interference fringes on surface structures to change colour (as in butterfly wings, etc)

B. Change the transparency of an object or its external environment

■ Photolithography used to change transparent material to a solid mask for semiconductor processing

■ Light - sensitive glass

C. In order to improve observability of things that are diff cult to see, use coloured additives or luminescent elements

■ Fluorescent additives used during UV spectroscopy

■ UV marker pens used to help identify stolen goods

■ Use opposing colours to increase visibility–e.g. butchers use green decoration to make the red in meat look redder

D. Change the emissivity properties of an object subject to radiant heating

■ Use of black and white coloured panels to assist thermal management on space vehicles

■ Use of parabolic reflectors in solar panels to increase energy capture

■ Paint object with high emissivity paint in order to be able to measure its temperature with a calibrated thermal imager

33 Homogeneity

Objects interacting with the main object should be of same material (or material with identical properties)

■ Gin ice cubes – Make ice - cubes out of the same fluid as the drink they are intended to cool

■ Food containers made of edible substances – ice cream cone

■ Container made of the same material as its contents, to reduce chemical reactions

■ Friction welding requires no intermediary material between the two surfaces to be joined ■ Temporary plant pots made out of compostable material

■ Human blood transfusions/transplants, use of bio-compatible materials

■ Join wooden components using (wood) dowel joints

34 Discarding and Recovering

A. Objects (or part of them) disappear after completing their useful function or becoming useless (discard them by dissolving, evaporating, etc) or modify them directly during the process

■ Dissolving capsule for vitamins or medicine

■ Bio-degradable containers, bags, etc.

■ Casting processes – lost-wax, sand, etc.

■ Female spiders eat the male after mating

■ During firing of a rocket, foam protection is used on some elements; this evaporates in space when shock-absorbance is no longer required

B. Restore consumable/used up parts of an object during operation

■ Self-sharpening blades – knives/lawn - mowers etc.

■ Strimmer dispenses more wire automatically after a breakage

■ Self-tuning automobile engines

■ Propelling pencil

■ Automatic rifle

35 Parameter Changes

A. Change the physical state (e.g. to a gas, liquid, or solid)

■ Transport oxygen or nitrogen or petroleum gas as a liquid, instead of a gas, to reduce volume

B. Change the concentration or density

■ Liquid soap

■ Abradable linings used for gas-turbine engine seals

C. Change the degree of flexibility

■ Vulcanize rubber to change its flexibility and durability

■ Compliant brush seals rather than labyrinth or fixed geometry seals

D. Change the temperature or volume

■ Raise the temperature above the Curie point to change a ferromagnetic substance to a paramagnetic substance

■ Cooking/baking/etc.

E. Change the pressure

■ Pressure cooker cooks more quickly and without losing flavours

■ Electron beam welding in a vacuum

■ Vacuum packing of perishable goods

F. Change other parameters

■ Shape memory alloys/polymers

■ Use Curie point to alter magnetic properties

■ Thixotropic paints/gels/etc

■ Use high conductivity materials – e.g. carbon fibre


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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