Abstract
A method is developed by which optimum-stress curves for a given material at any temperature may be calculated from the room-temperature optimum-stress curves for a different material. The only data required to perform this transformation are stress-strain curves of both materials. As examples, optimum-stress envelopes are obtained for wide columns and multiweb beams over a wide range of temperatures. Relations are developed between the properties of optimized elements of different materials so that the detailed dimensions of any element may be calculated by considering a properly selected equivalent aluminum element. An approximate procedure is developed for the determination of maximum life when creep is significant. The method is then extended so as to permit comparison of unprotected structures with insulated and cooled structures, on the basis of minimum weight-strength and as a function of temperature and exposure time. Thus these developments lead to a systematic procedure by which the optimum structural arrangement and material may be selected for a given loading and known thermal environment.
