mechanician

Sources of Inspiration

Text of Timoshenko Medal acceptance speech delivered at the Applied Mechanics Dinner of the 1988 Winter Annual Meeting of ASME in Chicago, Illinois.

I should like, first and foremost, to express my deep appreciation to the Applied Mechanics Division of ASME for the honor they have done me in awarding the Timoshenko Medal for 1988. Any scientist or engineer waged in research in mechanics, even one with the minimum of vanity, would be delighted and thrilled to have his work recognized by an award with such high prestige. In past years the Timoshenko medal has gone to some of the outstanding scientists of this century. As we have heard from Professor Leibovich, the inaugural award 31 years ago was to Stephen Timoshenko himself, and in the following year there was a bumper crop of three medalists: Arpad Nadai, distinguished for his work in plasticity, and those two giants of fluid and solid mechanics, Theodore von Karman and Geoffrey Taylor. The last-named of these medalists was my mentor and teacher, and the little I know about the doing of research in fluid mechanics was learned from him. I also had the privilege of editing the four volumes of Taylor's collected scientific papers, and this left me with a profound admiration and respect for his insight, originality and capacity for scientific discovery. My feelings about von Karman are similar, although I did not know him as well. I intend no disrespect for ASME when I say that the standard of the Timoshenko medalists has undoubtedly slipped a little over the past 31 years. My friend Bill Sears has done a brilliant job of covering up that decline, and I thank him warmly for his kind remarks while not believing all of them.

Comments on Discovery and Invention

Text of a talk delivered at the Applied Mechanics Dinner of the 1986 Winter Annual Meeting of ASME in Anaheim, California.

With regard to the topic of these comments, I was told that a title of some kind was mandatory so I gave a title which seemed reasonably impressive. Upon reflection, I have little to offer in the way of comments which are correspondingly impressive. It occurred to me that the forward motion of a crack in a structural material might be of some interest as a descriptive model. A 1950 technical paper, by Kies, Sullivan, and Irwin, reported that progressive fracturing usually occurs by the development and joining of advance separations and that these local behaviors tend to be rather abrupt. By use of motivation as a driving force and by substituting "advance ideas" for "advance separations," a plausible descriptive model of forward technological progress seemed possible. Of course, details related to the development and joining of advance ideas would be needed. These would include motivation, opportunity, guidance, and information exchange. In his 1985 Timoshenko Medal comments, Sternberg noted certain research management features which are not helpful. The conditions one likes for best progress certainly include benign methods of research management. After additional reflection on these and other complexities related to innovative progress, I decided that the descriptive model I had thought to develop was unlikely to be useful. So my comments will have a different nature. They will be memories and historic fragments related to my topic and they will be restricted to the strength of materials field.