A thermal deformation test technique robust to change in room temperature using multiple periodic heating

As the shape accuracy requirement of space-based space observation instruments becomes stricter, the measurement accuracy of thermal deformation tests needs to improve. The conventional test technique using static heating and evaluation in the equilibrium states before and after heat input is influenced by disturbances such as the change in room temperature and the thermal deformation of the jigs fixing the test article and measurement devices. The authors proposed a test technique using periodic heating and evaluation in the frequency domain. The evaluation in the frequency domain can eliminate the disturbances with a frequency sufficiently different from the heat input. The thermal deformation of multiple parts of a test article can be evaluated simultaneously by applying periodic heating with different frequencies to each part. An experiment and numerical analysis using a truss structure are conducted to evaluate the performance of the proposed test technique. From the experimental and numerical results, the elimination of the effect of room temperature change and the simultaneous evaluation of multiple parts of a test article are demonstrated. As a result, the effectiveness of the proposed thermal deformation test technique is shown.