Analysis Of Performance Of The Thermal Protection System Based On Multi-Scale Method

The thermal and mechanical performance of the ceramic thermal protection system(CTPS) and the metal thermal protection system(MTPS) is studied. TPS is used in the surface of missile and space shuttle, while the failure of these structures always occurs from fibers(which in composites only scale micrometers), so one of the basic features of composite structure is multi-scale.Multi-scale method in performance analysis of composites and structural calculations has been widely applied, and the numerical means tends to be finite element method. Multi-scale method is used to analysis the mechanical performance of CTPS and MTPS. The main studies are as follows.1) The multi-scale analysis procedure of TPS is established. Multi-scale analysis can be carried out follow the micro-macro-micro routine.2) For the CTPS, the finite element models of RVE are built to analyze the effect of element density on computation results and then to illustrate the proper way of modeling. The analysis of CTPS on macro-level is carried out and the results are compared with that of RVE. Then the analysis of CTPS on micro-level is carried out by using 3D and 2D computation models, and detailed stress/strain distribution are obtained in fibers and matrix.3) For the MTPS, the analysis procedure of the thermal strength is similar to that of the CTPS. The detailed distribution of stress/strain in fibers and matrix is obtained. Which should be mentioned is that different from CTPS, the calculation of temperature field of MTPS is more complicated, and only thermal conducting is considered here.Performance of heat transfer and strength of TPS is investigated, and the following conclusions can be drawn:1) Multi-scale method shows some advantages in the analysis of properties of composite structures, and which can be accomplish by using finite element method.2) Calculation of elastic constants of composite materials by using the single cell is a good approach, not only can guarantee good accuracy, but also can make up for deficiencies in the test(measurement error is big or not easily measured).3) Both of CTPS and MTPS can provide good thermal protection, and the performance of MTPS is better than that of CTPS under the calculation conditions in the study.In summary, the macro-meso scale analysis is used to study the performance of TPS. In the meso scale, the elastic constants of composite materials are calculated to provide the calculation parameters in the macro scale. In the macro scale, the mechanical properties of TPS are analyzed. Some useful conclusions have been obtained to evaluate the safety of structure and to guide the design of composite structures.