Strain‐Gauge Technique in Design

STRAIN‐GAUGE technique might, at first glance, seem so highly technical a subject as to occasion some surprise at interest in it at a time when production problems seem to require all of our attention. Actually, of course, the greatest possible aid to increased ease in production is to start with the original design and simplify the structure itself, resulting naturally in a simplification of the entire production problem right from the outset. Better understanding of the problems involved already has allowed considerable progress in the matter of reducing the complexity of aircraft structures. So far, every effort has been made to limit the application of the techniques about to be discussed to those problems for which solutions are needed most urgently, always with the idea in mind of reducing the factors of ignorance involved to the point that we are permitted to simplify the structures which may be in question. The very words “strain gauge” infer a primary concern with theory, due largely to their past limitation to laboratory work. They are, however, here discussed as a work‐a‐day aid to the structural designer, substantiating past decisions and supplying information for better future decisions. In general, these methods, in a halting sort of way, provide a seventh sense that permits the designer to see and understand the inner workings of a structure under load.