Design is a synthesis. We have a target in mind, usually given to us by our boss or client, and we use our imagination, creativity and whatever knowledge we gathered through our life. It is like a game of catch: catch as you can! No rules. Just bring results, and fast! And it better work, or else…
In our toolbox we have whatever was learned in university: some math, physics, strength of materials, and a lot more. Wonderful tools for analyzing anything, or that is what we believe. We are certain that if we encounter a problem too difficult to our analytical powers we can always study a bit deeper or ask an expert, A PhD possibly. Alas, our wicked boss or client as the case may be, won’t allow us! He does not have the time, the money or both. Hey there, you are the engineer, you should know everything and solve everything. Fast! If you have not been in this situation you are probably working for a large institution, where time and money do not count. Lucky you!
Practice makes perfect
Why can’t you design a simple mechanism? Suppose we have to design a mechanism to throw out a slice of bread from the toaster when ready. Oops… what should be the strength of the holding arm? The weight of the bread is so small that by calculating the stress we get a thickness of the metallic arm to be say, 0.124 mm. Hmmmm. It does not seem right! Shall we make it of plastic? What temperature will this piece reach? How to calculate the heat transfer? An endless line of problems, many seem too difficult to solve by the tools we have. Maybe we should ask for a stronger FEA tool, if we get the budget and time! And yet, there are toasters who do the job pretty nicely. And it seems some of them were even designed by less educated people then us, even before FEA tools were even thought of. How come?
Did I make my point? The university gave us tools that are unfortunately sometimes useless in real life, and going back to ask our professor does not seem to work either. It will take too long to get the answer, and it will not solve the problem at all. We shall have to make two professors work together on this stupid problem: experts for strength and for heat transfer. Then, each will start by demanding a computer model to analyze. But, wait a minute! There is no model yet! We still have to design it in order to have a model.
This simple invented example demonstrates it all. Design is a vicious circle, where in order to use our tools to calculate it we must have it finished first. Nothing I wrote here is new. Everyone who does design knows it. And yet, in spite of this seemingly vicious circle we create good designs all the time, some of them extremely complex. What is the secret here, and why this secret has not be revealed to us in the university?
Design is art
There are several answers to that. The teachers in the university are mostly scientists. They research and make the formulas. They, as a rule, do not do design work themselves. They are expert for analysis, but design is the art of synthesis. So why are there no experts in synthesis too? This is because synthesis appears to be simple. It seems like everybody can do it, it only requires some creativity and some analytical tools, right? Wrong! But they don’t know it. It does not require these high mathematical skills, so it does not count…
The sad truth is that design is a very complex art. Many can do it, but few can do it right. There are no rules and definitely no perfect algorithms. There are few books on the subject but they don’t look like much. Not scientific enough – just like this blog. And there are no authorities: nobody ever came out and called himself master in the art of design. There are only experts in designing certain things.
True, you cannot make an algorithm for design. If we could, we would have given this job to computers. It is only us, humans, that can do real design work, much like the inability of computers to create art. Well, computers do art sometimes, but they are years away from being able to design anything at all, which is more that copying and optimizing existing design.
So, is it hopeless? Must we jump into the deep water and hope not to sink? Not quite. There are some general fuzzy rules that we experienced engineers use, knowingly or instinctively. In my following blog posts, I shall try to expose some of these rules.