Design And Performance Evaluation Method Of Integrated Thermal Protection Systems

Integrated Thermal Protection System (ITPS) both fufiling thermal protectionand load bearing capabilities is more structurally efficient than conventional TPSconcepts, and becomes an important research area of TPS. Howerver, due to thecontradiction between thermal-mechanical function, the weight advantage of ITPSis theatened, thus a design method which can balance contradiction is desired.On this motivation, this thesis starts with the heat short and thermal mismatcheffects caused by the contradiction between thermal and mechanical function,which was further validated by thermo-mechanical analysis result of typical ITPS.Though redunction of heat short flux and adjustment of web deformability, servalITPS concepts are developed. The improvement of redesigned ITPS concepts areexplored by the corresponding thermal and mechanical response under typical RLVreentry loads. The effect of structure redesign on ITPS load carrying capabilitywas assessed though homogenized elastic constants.In order to validate the reasonability of the developed ITPS concepts, testarticle of initial and redesigned ITPS were prepared, and tested in graphite platevaccum furnance. The heat short effect and the thermal performance improvementof redesigned concepts were discussed based on the experiment. Unit cells ofdifferent ITPS concepts were also prepared and tested under compressive load toinvestigate the influence of structure redesign on ITPSs’ out-of-plane strength.The overall performance of ITPS is determined by various factors. In thisthesis, factors including structural design reasonability, structural efficiency,design complexity and manufacturability were considered. The relative evaluationmethod, and the fuzzy method of different ITPS concepts against a single factorwere presented. The latter is considered to be more more suitable for ITPSevaluation though the comparison of classical and fuzzy set theory. On thesefoundation, a performance evaluation method of ITPS employing fuzzy decisionmodel was establised. A comparison between different concepts were made underdifferent weight coefficients adopting this method and the maximum membershipprinciple. The result indicated that the fuzzy logic is more objective and inclusivein ITPS evaluation.Followed by the structural design and evaluation of ITPS, the structuraloptimization of ITPS was discussed. It can be desicribed as an optimizationproblem with areal density as objective function and maximum temperature,maximum stress, minimum buckling eigenvalue as design constraints. The criticaldesign load cases were determined though the trend revealed by the relationship between structure response and aerothermal and aerodynamic loads. Thecorresponding solution method of the optimization model was established based oninterior-point penalty function algorithm, and genetic algorithm, which wereapplied to corrugated core ITPS and web-stiffened ITPS respectively. A significantimprovement of structural efficiency of web-stiffened ITPS was achived thoughoptimization.