Dynamic response of pre-loaded structures subjected to combined extreme environments

A series of experiments was performed on Hastelloy X plates which were subjected to a combination of extreme temperatures, in-plane tensile loading, and transverse shock loading. To achieve these conditions a shock tube apparatus was used in conjunction with a novel hydraulic pre-loading fixture and propane flame torches. In order to understand the effects of shock load magnitude on the deformation behavior of the plates, two series of experiments were carried out at peak shock pressures of 1.7 MPa and 3.1 MPa, respectively. Both series of experiments were conducted over a range of temperatures from room temperature to 900°C. High speed photography and Digital Image Correlation (DIC) were used to obtain three-dimensional, full-field deformation information. Side view images were also captured to validate the DIC results. The addition of a tensile pre-load reduced the maximum deflection for all temperatures. However, a higher magnitude of the tensile pre-load did not further reduce the maximum out-of-plane deflection of the plate for temperatures higher than 400°C. The specimen deformation increased with increasing temperature until 800°C. However, at 900°C, due to anomaly in material constitutive behavior, the specimen deflection was observed to be lower than at 800°C. An indentation mode of deformation was observed in some instances of the 3.1 MPa peak shock pressure experiments, particularly at higher temperatures.