made-by-monkeys2

Good ideas with bad execution, or good execution of what should be bad ideas - an analysis of inferior, off-beat or malfunctioning products, and how other people's failures can help us design better stuff.

Residual Stress Causes Ceramic Plate to Crack

pict0143a.jpgView crack detail. My husband is known for his creative special effects, usually involving food, like the time he grilled eggplant slices and formed them into stacks vaguely reminiscent of that famous leaning tower in Italy. Just as he sliced into his own architectural wonder, a live beetle scuttled out from under his stack, which seemed like a really interesting, if slightly repulsive, way to work protein into the menu. The other night, however, he truly outdid himself. As he was taking one of our Waechtersbach ceramic dinner plates from the cupboard, he heard a cracking noise emanating from it. Upon inspection, he observed a radial crack about 3 inches in length.

The question is whether the notch (see crack detail) was a crack initiation site, or whether the notch area simply flaked off during the event, which I believe was caused by residual stress in the ceramic, most likely improper annealing. Most engineering students learn early on why when you cool things down, you need to cool them down slowly. If residual stress is indeed the culprint, then the mere act of my husband picking up the plate and taking it out of a cool closet and in proximity of a warm oven may have providede enough energy to get the crack to propogate. Either way, with this plate and a busted pewter serving fork that succumbed to bending stresses recently, I now have a perfectly matched Made by Monkeys dinnerware set! View broken fork

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2 Comments

  1. September 03, 2008 09:45

    The measured residual stress data was used in fatigue crack growth simulations in order to compare the behavior of the analyzed plate.The residual stress, which is relevant for crack. growth, was evaluated in a metal–matrix composite plate.
    ==================================================
    Vincent
    Crack Cocaine

  2. September 03, 2008 09:01

    The residual stress, which is relevant for crack. Growth, was evaluated in a metal–matrix composite plate.This has been solution treated at 505.
    The measured residual stress data was used in fatigue crack growth simulations in order to compare the behavior of the analyzed plate.
    =================================================
    Vincent
    Crack Cocaine