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1.7.12 Appendix - contradiction matrix parameters 36- 40

Aggiornamento: 8 nov 2021

36 Phase Transitions

Use phenomena occurring during phase transitions. (e.g. volume changes, loss of absorption of heat etc.)

■ Latent heat effects in melting/boiling

■ Soak rocks in water, then freezing causes water to expand –thus opening fissures in rock, making it easier to break

■ Heat pumps use the heat of vaporization and heat of condensation of a closed thermodynamic cycle to do useful work

■ Volume expansion during water-to-steam transition

■ Superconductivity

37 Thermal Expansion

A. Use thermal expansion (or contraction) of materials

■ Fit a tight joint together by cooling the inner part to contract, heating the outer part to expand, putting the joint together, and returning to equilibrium

■ Metal tie-bars used to straighten buckling walls on old buildings

■ Thermal switch/cut-out

■ Shape memory alloys/polymers

■ Shrink-wrapping

B. Use multiple materials with different coefficients of thermal expansion

■ Bi-metallic strips used for thermostats, etc

■ Two-way shape memory alloys

■ Passive blade tip clearance control in gas turbine engines

■ Combine materials with positive and negative thermal expansion coefficients to obtain alloys with zero (or specifically tailored) expansion properties –e.g. cerro - trualloy used in the mounting and location of fragile turbine blade components during manufacture operations

38 Accelerated Oxidation

A. Replace common air with oxygen-enriched air

■ Scuba diving with Nitrox or other non-air mixtures for extended endurance

■ Place asthmatic patients in oxygen tent

■ Nitrous oxide injection to provide power boost in high performance engines

B. Replace enriched air with pure oxygen

■ Cut at a higher temperature using an oxy-acetylene torch

■ Treat wounds in a high pressure oxygen environment to kill anaerobic bacteria and aid healing

■ Control oxidation reactions more effectively by reacting in pure oxygen

C. Expose air or oxygen to ionising radiation

■ Irradiation of food to extend shelf life

■ Use ionised air to destroy bacteria and sterilise food

D. Use ionised oxygen

■ Speed up chemical reactions by ionising the gas before use

■ Separate oxygen from a mixed gas by ionising the oxygen

E. Replace ozonised (or ionised) oxygen with ozone

■ Oxidisation of metals in bleaching solutions to reduce cost relative to hydrogen peroxide ■ Use ozone to destroy micro-organisms and toxins in corn

■ Ozone dissolved in water removes organic contaminants from ship hulls

39 Inert Atmosphere

A. Replace a normal environment with an inert one

■ Prevent degradation of a hot metal filament by using an argon atmosphere

■ MIG/TIG welding

■ Electron beam welding conducted in a vacuum

■ Vacuum packaging

■ Foam to separate a fire from oxygen in air

B. Add neutral parts, or inert additives to an object

■ Naval aviation fuel contains additives to alter flash point

■ Add fire retardant elements to titanium to reduce possibility of titanium fire

■ Add foam to absorb sound vibrations – e.g. hi-fi speakers

40 Composite Materials

Change from uniform to layered/composite (multiple) structures

■ Aircraft structures where low weight and high strength are required

■ Composites in golf club shaft

■ Concrete aggregate

■ Glass-reinforced plastic

■ Fibre-reinforced ceramics

■ Hard/soft/hard multi-layer coatings to improve erosion properties


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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