Why we need controlled failure

We live in a world obsessed by perfection.  Everything is supposed to be better if it’s shiny, defect-free and stronger than a Sherman tank. 

But be careful what you wish for, because a flawless world wouldn’t work nearly as well. Imperfections are tools, and we would be lost without them.  

Of course, flaws are not always convenient.

Imagine bending a long thin object, like a bar of chocolate. If the chocolate has flat surfaces, each side is stretched evenly. It’s hard to break, but if you put a notch in it the section of chocolate just underneath also has to do the job of the bit you’ve taken out. The chocolate will break at the notch. It’s not because it’s thinner at that point but because the sharp point of the notch concentrates the force in a very small area.

In a flawless object the stress you put on a material by pushing, stretching, bending and twisting is relatively evenly spread. Features like notches, voids and tiny cracks make the pattern of stress more complicated, concentrating the stress in some bits and relieving it in others. If you could see stress as colours, every object you pushed on would suddenly light up with bands of colour and the flaws would be tiny pinpoints of dazzlingly bright light. Those pinpoints are vulnerable, overloaded already, they can’t take much more.

But the effect of a flaw doesn’t have to be catastrophic. Flaws give us control. If you put a notch in a material you know exactly where it is going to break. Chocolate is the obvious example, but there’s also the perforations in kitchen towel, the zig zags at the top of crisp packets, the notch moulded in a tablet for snapping in half and the fold you put in a piece of paper before you tear it.

Having a line of holes or a notch also means that you don’t have to pull the object as hard to get it to break. All those little defect are concentrating the force you use, amplifying what you have to offer.
 
We don’t even have to put them there ourselves. Think about peeling a banana – those ridges down the sides are weaker than most of the skin, so they give way first. Breaking into a banana is something you can do in a satisfyingly beautiful way. Not so with an orange. They don’t have any external weaknesses, so you have to do a lot of work to earn you pile of messy tiny pieces of orange peel and fingernails full of zest. 

But once inside, aren’t segments convenient? Perfection is fairly boring anyway; just like people, it’s the flaws that makes most things more interesting.

For help putting your packaging to the test, contact Stable Micro Systems today.

---

For more information on how to measure texture, please visit the Texture Analysis Properties section on our website.

The TA.XTplus texture analyser is part of a family of texture analysis instruments and equipment from Stable Micro Systems. An extensive portfolio of specialist attachments is available to measure and analyse the textural properties of a huge range of food products. Our technical experts can also custom design instrument fixtures according to individual specifications.

No-one understands texture analysis like we do!

To discuss your specific test requirements click here...