The action is from the abstract towards more and more detailed solutions. At a suitable level the pen and paper sketching is stopped and the work is continued in a CAD-program.
Model Aided Design - MAD
It is often useful to build and test some simple models to verify the function of concepts or to increase ones understanding of the concept.
Favored materials are model clay, plastic foam, LEGO-bits, balsa wood, and cardboard.
As with PAD, there are some merits to models that computers lack. The tactile feedback and the visual impressions, and the possibility to mimic the real thing differ from when using computers only. Also the impressions are remembered differently and more vivid by using models.
The forte of using computer software for trying out mechanisms is the possibility to get exact data of displacements, forces, velocities, and accelerations.
Estimating extremes
Typically a specification is a noun and a number. Such specifications are necessary but seldom sufficient. Just designing to specifications is not enough.
To find the best solutions it pays to think of the worst cases, the extremes, and to visualize extreme usage of the product. Lets say you design a new camera. Then think of what the camera must withstand onboard a sailboat during an around the world race. Water, cold/hot weather, shocks from tumbling around at the bottom of the boat. This gives you a better, truer, understanding than simply stating that the camera should withstand three consecutive half-sine pulses of amplitude 300 m/s2 and period 30 ms.
By thinking of the extremes and solving for them we almost automatically also solve for the in-betweens.
There is also a contrast effect of regarding opposing extremes that helps clarify problems and lets us see functional solutions with more ease.
