Dear Colleagues,

You probably know the trick to stop a crack on your car windscreen (windshield to you, North Americans) from spreading. Simply, drill a hole near the tip (or end) of the crack. This makes the crack less sharp and distributes the stresses over a larger area and in more directions. This reduced stress stops the crack from spreading. A great solution.

The Same Principle Applies
The same principle applies to rounded corners in a range of objects from tables to machine parts. A rounded window corner spreads stress over a larger area; whereas a sharply pointed (or squared) window focuses the stress on one point in the system. You can confirm this when you catch one of your body parts on the sharp edge of a table – it is painful.

A Key for Good Engineering Design
This is a crucial concept for all engineering design – a simple formula for reducing or distributing stress in many directions.

And on the line of ‘cracks’ or ‘cracked’, Bernard Meltzer remarked: A true friend is someone who thinks that you are a good egg even though he knows that you are slightly cracked.

Thanks to ‘101 Things I Learned in Engineering School’ by John Kuprenas with Matthew Frederick for some thoughtful commentary.

Yours in engineering learning,