146. How Light Should a Fastener Be?

Paper

Abstract

One design engineer said to me recently that the lowly self locking nut had really come into its own in modern aircraft design. Among the hosts of sizes, types and configurations, there is a female threaded fastener for almost any job – – from sealing to controlled seepage, for functioning at temperatures ranging from – 300degree F to 1600o F, and from controlled tensile failure to 280,000 psi. They come in dimensions for spaces only slightly larger than a pin head to 6′ across hexagon corners. They are available from 00 to 4 1/2 inch threads and in all useful materials from brass to aluminum, to chromel, to Inconel X and. others. The evolution of self locking nut design, weight saving, and end use has been rapid, indeed.
With all the changes in fasteners, and all the claims and counterclaims, it may be well to stand back and review just what has happened, so that the ‘good of the new’ may be added to the ‘good of the old’ to provide real progress.
The objectives of this presentation will be to analyze some of the most significant of these new developments and to highlight a few of the features they provide, and a few of the inherent limitations; to evaluate them in terms of the weight-strength-structural concepts with which you, as weight engineers, are particularly concerned; and to integrate, or perhaps suggest a perspective, for utilization of the new designs in relationship to some of the existing designs which may not be completely familiar to you.