Fundamentals Of Reliability And Maintainability

Fundamentals of Reliability and Maintainability Second Edition Steven Davis This book was written by a U.S. Government employee as part of his normal duties; therefore, it is in the public domain. ii Dedication The second edition of this book is dedicated to the memory of my good friend and roommate at Georgia Tech, Joseph Lester “Joey” Wilson (Textiles, 1978), Feb. 27, 1956 — Jan. 3, 2004. Rest in peace, Joey. iii iv Dr. Robert Abernethy begins his New Weibull Handbook with an excerpt from Oliver Wendall Holmes’ “The Deacon’s Masterpiece.” I thought it appropriate to begin with the entire poem—a classic 19th century work on reliability. The Deacon's Masterpiece or, The Wonderful "One-Hoss Shay" A Logical Story by Oliver Wendell Holmes HAVE you heard of the wonderful one-hoss shay, That was built in such a logical way It ran a hundred years to a day, And then, of a sudden, it—ah, but stay, I'll tell you what happened without delay, Scaring the parson into fits, Frightening people out of their wits,— Have you ever heard of that, I say? Seventeen hundred and fifty-five. Georgius Secundus was then alive,— Snuffy old drone from the German hive. That was the year when Lisbon-town Saw the earth open and gulp her down, And Braddock's army was done so brown, Left without a scalp to its crown. It was on the terrible Earthquake-day That the Deacon finished the one-hoss shay. Now in building of chaises, I tell you what, There is always somewhere a weakest spot,— In hub, tire, felloe, in spring or thill, In panel, or crossbar, or floor, or sill, In screw, bolt, thoroughbrace,—lurking still, Find it somewhere you must and will,— Above or below, or within or without,— And that's the reason, beyond a doubt, That a chaise breaks down, but doesn't wear out. v But the Deacon swore (as Deacons do, With an "I dew vum," or an "I tell yeou ") He would build one shay to beat the taown 'n' the keounty 'n' all the kentry raoun'; It should be so built that it couldn' break daown "Fur," said the Deacon, "'t's mighty plain Thut the weakes' place mus' stan' the strain; 'n' the way t' fix it, uz I maintain, Is only jest T' make that place uz strong uz the rest." So the Deacon inquired of the village folk Where he could find the strongest oak, That couldn't be split nor bent nor broke,— That was for spokes and floor and sills; He sent for lancewood to make the thills; The crossbars were ash, from the straightest trees, The panels of white-wood, that cuts like cheese, But lasts like iron for things like these; The hubs of logs from the "Settler's ellum,"— Last of its timber,—they could n't sell 'em, Never an axe had seen their chips, And the wedges flew from between their lips, Their blunt ends frizzled like celery-tips; Step and prop-iron, bolt and screw