There are a few scientific material/process selection methods used in engineering today that make it possible to delegate most of this otherwise lengthy and complex hand-calculation to a computer. Here is a freely available example.
Usually it'll go something like this:
- Define requirements and quantify them
- Screen out unacceptable options
For example, a seat can't break with one human's weight on it, a drinks container can't be water-permeable or leach toxins, windows can't be opaque, a kettle can't be made out of chocolate... above and beyond basic functionality, properties are then optimised to give the best safety margins and performance possible.
- Define weighting for optimal properties
A method often used for this is called "the digital logic method", where properties are repeatedly matched off against each other in pairs, somewhat like a tournament only better because all combinations are considered, and weighting factor is determined based upon tallying up points from each comparison. When a part being made is safety-critical, such as a bridge or a high-pressure tank, properties like strength, stiffness, corrosion resistance, etc. will come out taking precedent. Other applications may produce quite different requirements, like heat and sound insulation for wall materials, flexibility and 'breathability' (air permeability) for clothing materials.
- Find an optimal solution
Once performance of these requirements is all counted up for comparison, there may be one or more shining superior options, for example certain steels or aluminium-titanium alloys for a vehicle chassis.
After that point the benefits of a cooperative global resource management system show up, as this process is repeated at a higher order, which isn't usually possible amongst manufacturing corporations and nations that are in competition with each other. By this I mean we look again at a few optimum materials that have been proposed each for cars, trains, spacecraft, or even humble shelves, and work out how best to distribute resources between applications and regions.
This might turn up a solution for example where the greatest overall energy saving is made by using lightweight alloys everywhere in spacecraft, and some mixture of them in cars and trains, while shelves would almost certainly be steel, unless they were specified to support something lightweight in which case they could even be made from wood or hemp composite provided there is no significant fire hazard where they are placed.
There may even be regional differences in materials used, for example if potential performance benefits are marginal between two materials and one is easily available in a local scrapyard, landfill or mineral deposit, then that easily available material could be used first.
It is likely that in this higher order, without basing individual choices heavily upon abstract 'monetary cost', a balance of energy saving could be found by using easily renewable materials such as hemp-bioplastic composites in small electronic device cases where maximising their strength/weight performance could become absurd.
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Originally Posted by Peter Jolliffe
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