This paper presents an overview of a newly developed code, NESTEM that analyzes structural components subjected to varying thermal and mechanical loads. This program is an enhanced version of NESSUS and has all the capabilities of NESSUS. In addition, it allows one to perform heat transfer analysis. The basic heat transfer variables can be included as random variables along with the mechanical random variables to quantify risk using probabilistic methods and to perform sensitivity analysis. The analysis capabilities of NESTEM have been demonstrated by analyzing a cylindrical combustor liner. This analysis includes evaluating stresses and their variations at critical points on the liner using material properties, pressure loading and basic heat transfer variables as the random variables. The heat transfer variables are convection temperatures, film coefficients, radiation temperatures, emissivity, absorptivity and conductivity. Cumulative distribution functions and sensitivity factors, for stress responses, for mechanical and thermal random variables are calculated. These results can be used to quickly identify the most critical design variables, in order to optimize the design, to make it cost effective.

cost (TOC) as similar technology subsonic transports and much worse than that relative to contem-The major challenges confronting the propul-porary technology aircraft. Very large airframe sion community for civil supersonic transport and propulsive efflciency improvements will be appllcations are Identlfled: high propulsion sys-requlred to alter this situation. In our quest for tem efficiency at both supersonic and subsonic greater productivity through increased speed, we cruise condltlons, low-cost fuel with adequate are also confronted with ever increasing dlfflculthermal stability at high temperatures, low noise ties arising from high ram temperature levels. The cycles and exhaust systems, low emission combustion challenge is to utllize advanced materlals to cope systems, and low drag installatlons. Both past with the high temperatures without incurring excesprogress and future opportunities are discussed in slve weight and cost penaltles. In addition, the relation to perceived technology shortfalls for an Inabllity of traditional low-cost fuels to provide economically successful airplane that satisfies adequate thermal stabillty impedes the pursuit of envlronmental constraints, higher speeds. Expensive JP-type fuels reach thermal stability limits at speeds near Mach 4, but low Unclassified Unclasslfied 18 A02 NASA FORM 1626 OCT86 *For sale by the NationalTechnicalInformationService,

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