Product Design – Nevan Clancy Hanumara, PhD

Why Strain Relief Matters

It’s late at night on an unfamiliar street, where I have just driven out to help a friend change a flat tire. Of course, the donut is deflated too but, not to worry, I have my trusty Slime brand compressor. I plug it into the 12 V cigarette lighter and roars to life, only to start to sputter. Only by continually wiggling the cord could we inflate the tire and send my friend safely on her way. The symptoms of poor engineering were familiar.

I dissembled the plug and found the wire connected to the positive terminal (connected to the tip) sparked, melted and disconnected and the negative wire hanging on by a few strands. While I am sure Slime has thought about the mechanism of their pump, it’s obvious that no one considered the reliability of the humble plug, despite proudly mounding their logo onto it. It’s failing are multiple:

Why user testing matters!

This morning I boarded a Delta flight on an Airbus A321, hung my jacket, stowed my briefcase and found a seemingly safe place for my hat in an overhead bin corner. Oddly, the bin took a couple of pushes and shoves to close, but I thought nothing of it, until I fetched my hat back at the end of the flight, whereupon I found a hole punched right through it by the latch mechanism, see photo.

As far as I can tell, with the flight attendant corroborating, this overhead bin design is unique to the Airbus A321s in Delta’s fleet. There is no side protection, hence any jacket, sweater or soft object that projects over what little bin edge there is will either jam it, thus slowing down boarding as passengers search for the invisible blockages, be squished or engage the latch and end up torn or perforated. All sorts of soft goods are at risk and I’m glad I did not lose a favorite blazer.

Nevan Clancy Hanumara, PhD

Category Archives: Product Design

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