High-temperature, dynamic strain test platform to evaluate capacitance based strain gauges for in-pile deployment

This paper presents a test platform capable of applying representative in-pile thermal and monotonic, cyclic, and dynamic force loadings which induce target strain into representative in-pile components. The system's form is that of two concentric linear delta robots and an intermediate vertical furnace. The enabled relative motion between the end effector platforms will result in enhanced performance compared to single delta or nearly any other Cartesian translational system by doubling the speed, quadrupling the workspace, and being able to actively prevent vibrational damage to its mechanical components. The employed force/torque sensors and motors are sized to apply/measure the target ranges, sensitivities, and bandwidths representative of in-pile loadings for objects of interest. The system has been designed to accommodate many in-pile geometries including a conventional (15mm OD x 12mm ID) fuel pin. Collet chucks attached to the force/torque sensors are designed to secure the pin ends as it transgresses through a furnace tube cavity allowing it to be thermally and/or force loaded. Such a configuration allows material characterization and sensor qualification/development to be performed. The system's current configuration will have the ability to execute a comprehensive thermal and force loaded strain gauge study. Considered strain gauges in this future study will include conventional resistive strain gauges, weldable resistive strain gauges, and printed capacitive based strain gauges. The printed capacitive strain gauges being developed by this effort are of highest interest due to preliminary results indicating that their performance measures are more compatible with in-pile environments than their commercial counterparts. The test platform will be a critical element in validating the performance of the employed nuclear grade inks for aerosol jet printing, the printing and physical characterization of the printed structures, and the evaluation of sensor performance pre and post-irradiation.