PSI - Issue 60

Sarath Chandran Nair S. et al. / Procedia Structural Integrity 60 (2024) 564–574 Sarath Chandran Nair S. / Structural Integrity Procedia 00 (2023) 000 – 000

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Fig. 6. (a) Test machine; (b) specimen mounted in the machine for testing

4.4. Test procedure Tests are carried out for tension/compression strain conditions. Initially room temperature test was done to simulate hydrotest conditions of thrust chamber. Test done was by strain control method. Strain rate of 0.1%/sec was used for both tension and compression tests for loading and unloading. Visual inspection and Dye Penetrant (DP) inspection were used to observe surface defects on the coating. Subsequently high temperature tests were carried out. Heating rate of 40°C/min was used. 10 minutes soaking time was given after reaching the required test temperature. Initially no strain was given to the specimen to check the coating integrity on thermal expansion without any mechanical load. Strain cycling at high temperature was carried out for 3 cycles in a batch with heating and cooling cycles. DP tests were carried out after each stage and images were captured to keep a record of crack formation and its development. Test procedure for each specimen is given in table 5.