In this work, investigation of the thermo-structural response of steel-composite rocket nozzle is carried out using the finite element method; in the form of commercial package ANSYS. A validation of ANSYS for thermal and structural analysis is done first for simple problems, then the analysis done with the nozzle. The result of thermal analysis shows that thermal loads have a great effect in generating a huge amount of stresses on the nozzle structure (more than 60% from the total stresses on the nozzle). The convictive heat transfer coefficient has a great effect on the temperature transferred to the nozzle wall. The composite material resists temperature augmentation, so it is regarded as a thermal protection material.

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Thermal properties of chopped composites are important parameters for determining application and use of this category of materials. An experimental identification for thermal properties of different composite materials was conducted. In order to investigate the effect of fiber, three different chopped fibers with a phenol resin as a matrix; Carbon fiber, Basalt, and Fiberglass, were selected to determine their thermal properties. Also, the matrix is changed for carbon fiber; phenol resin and epoxy resin, to show the influence of matrix material. Two important parameters were investigated which are the thermal conductivity (TC) and the thermal expansion coefficient (CTE). For the four materials, the thermal conductivity obtained is very low with a range of K = 0.159 w/m °c for the Carbon / Phenol to K = 0.1942 w/m °c for the Carbon / Epoxy, so those materials are used as thermal insulators. On the other side, thermal expansion coefficient has also very low negative values for the Phenol based composites with a range of -146.6 µm/m°c for fiber glass / phenol to -273.7 µm/m°c for carbon fiber / phenol, and for the Epoxy based composites the CTE has a low positive value which is 1049 µm/m°c for carbon fiber / epoxy .

This work deals with the characterization of chopped fiber glass composite. The resin matrix was a phenol base. Sheets of this composite have been cured and cut to make sample specimens for testing. Four mechanical testing have been conducted for these material including tensile test at different temperatures, bending test, compression test and hardness test. Three thermal tests including thermal conductivity determination, thermal expansion coefficient determination and ablation test have been conducted. The results show that this material has very good thermal properties capable of resisting high temperatures.A nozzle for rocket motor has been made from this material as insulators, and static firing test has been conducted and the temperatures inside this composite material have been measured. Investigation of the thermal loads response of composite nozzle has been done using FE using ANSYS package software and the calculated temperatures have been recorded from the same places that chosen in the real firing test. By comparing the measured and obtained temperature for the fiber glass, there is a great agreement between them. The selected composite material resists the high temperatures so this used as thermal protective material.