Tuesday, July 26, 2016

Sometimes Cause Is More Important than Effect

Review: Why Things Break by Mark Eberhart

In this delightful treatise, materials theorist Eberhart explores the whys of the ways in which materials fail. This is not like the engineering question, "what cross-sectional area of substance x is required to sustain stresses of force y for a time period of z, under given environmental conditions." Eberhart explains:
...I usually say, "I am a quantum chemist"...  [T]o have fun, however, I say, "My research is concerned with the study of why things break." Usually a look of satisfaction appears on the questioner's eyes as he says, "Oh, so you are a mechanical engineer...." Now the fun begins, as I say, "No, I study why things break, not when."

Eberhart's decision to go into the field of quantum chemistry rose out of a childhood fascination with cracks and fractures in his marble collection. Why, he wondered, were the marbles that actually entered play so ugly and pitted? Why was the beautifully crazed baked marble (a fad when he was a child) so fragile? At college in Colorado, Eberhart lost his skis to a fracture and his Kevlar kayak to disastrous delamination in a single season, and this solidified his decision to change schools.
Did you know—
It took more than an iceberg to sink the Titanic.
The Challenger disaster was predicted.
Unbreakable glass dinnerware had its origin in railroad lanterns.
A football team cannot lose momentum.
Mercury thermometers are prohibited on airplanes for a crucial reason.
Kryptonite bicycle locks are easily broken.—from the publisher's product description.

At MIT, Eberhart would delve into the basic causes for fracture, working with Nobel-level luminaries in the new field of quantum chemistry—because we know more about what happens after materials break than we do about what happens just before they fracture. These studies would examine such disparate topics as why beating bronze and copper hardens them, why Japanese samurai swords could be hard on the edge and flexible in the shaft, what adding carbon to iron does that makes steel both harder and less brittle than wrought iron, and why the Titanic failed despite a design that should have made her able to stay afloat after the collision.
Graphite is made from carbon atoms tightly bound together into two-dimensional sheets; these sheets are then loosely bound together to form a two-dimensional crystal... graphite is said to be anisotropic, meaning it has very different properties depending on the direction in which it is "cut." When pulled in a direction that lies in the carbon sheets, graphite is very strong, making it an ideal substance from which to make tennis rackets, golf clubs and bicycles. At the other extreme, graphite is used as a lubricant because the weakly-bound sheets of atoms shear so easily.

Mark Eberhart also explores the toughness of materials, looking at where the energy of fracture goes when something breaks, at the historical quest for tougher, more-resilient materials, and the way entire scientific philosophies have grown around (and been broken by) discoveries of tougher substances. Along the way, he explains several puzzling catastrophes (the Challenger disaster and the in-flight fracture of an Aloha Airlines plane among them), and gives us some solid cause for worry whenever a man-made structure is used in a new or radically-extended way (as with hundreds-of-miles-long oil pipelines or bungee-jumping stunts.)

Eberhart makes this exploration almost painless, except the winces we share as we read of someone else's painful discovery. (The tale of a five-man bungee jump that drastically overloaded the tensile strength of the cable comes to mind.) Ranging from atomic-physics concepts to the studied attempt to break a Corelle dinner plate, this book is delightful, enlightening, and very intriguing.