## 3 Component Tests  
### Experimental Setup  
The blast tests on sandwich components were conducted in the SIMLab shock tube facility (SSTF) at Norwegian University of Science and Technology (NTNU). A detailed description of the SSTF is given by [PERSON] et al. [26], while Figure 5 shows a schematic overview of the shock tube. It consists of a high-pressure chamber (the driver), separated from a 16.10 m long low-pressure chamber (the driven) by a firing section. In this study, the test specimen is placed at the end of the driven section, to the right in Figure 5. Aluminium inserts are used to change the volume of the driver in 0.25 m increments. For these tests, the driver length was 0.77 m. The firing section consists of several independent chambers separated by diaphragms. This separation allows for a stepwise pressure gradient between the high-pressure driver and the low-pressure driven (at ambient pressure in these tests). The pressure in the driver is released by a controlled venting of the firing section, causing successive rupture of the diaphragms. By keeping the length of the driver section short compared to the driven section, the resulting pressure wave after firing takes a form similar to the one obtained in a free-field air blast explosion [26].  
The sandwich components were attached to a flange at the end of the driven section by two clamping flanges and twelve M24 bolts and nuts, shown in Figures 6 and 7. The bolts were tightened to 2 Nm using a torque wrench to avoid excessive compression of the foam core. An additional set of nuts were added to prevent the bolts and clamping frame from unscrewing during loading. In the following, the skin closest to the driven is named the front skin and the skin furthest from the driven is named the back skin. The planar shock wave impacts an area of the front skin measuring 300 mm \(\times\) 300 mm. The test specimen and the end of the driven were surrounded by a closed dump tank equipped with windows. Two synchronised Phantom v2511 high-speed cameras (Vision Research Inc., Wayne, NJ, USA) placed in a stereovision setup overlooked the back skins and recorded the blast response at a frame rate of 37 kHz with an image size of \(768\times 800\) pixels. The pressure loading was measured with two pressure sensors, located 0.245 and 0.345 m upstream of the test specimen. In Figure 5, these pressure sensors are denoted Sensor 1 and Sensor 2 respectively, abbreviated to S01 and S02 in the following. The pressure measurements were synchronised with the high-speed cameras, i.e., operating at a recording rate of 37 kHz. Three-dimensional digital image correlation (3D-DIC) analyses were conducted based on the high-speed video images and the in-house DIC-software eCorr. Before testing, the stereovision setup was calibrated using an 80 mm diameter cylinder with an applied checker pattern. In total, five images of the cylinder in various positions were used in the calibration process. Out-of-plane displacements were calculated based on the image sets from the synchronised cameras, comparing the relative displacement of the plate to the reference (or undeformed) state. Before each test, a speckle pattern required for 3D-DIC, as seen in Figure 6, was applied to the back skin with an aerosol nitrocellulose lacquer and a polymer template.  
Figure 5: Overview of SIMLab Shock Tube Facility (SSTF) [26].