6. Comparison of calculation predictions and test results

Global validation can only be carried out using information from nozzle firings on the bench or in flight. Two types of information are used for this validation:

• visual observations before, during and after shooting ;

• measurements recorded during the material exposure and cooling phases.

Visual observations can be used to determine whether or not the material has fractured, as well as which areas are healthy and which are pyrolyzed. Despite the difficulties of identifying the exact moment of failure, these observations are the only possible global validation of failure criteria in phenolic composite materials.

Measurements recorded during the firing process are used to validate the thermal model using carefully placed thermocouples, and to validate...