###### Abstract
They highlighted the influence of the time interval between the fragment impact and the blast loading on the response mode (cracking, dishing, and plugging) of an aluminum plate subjected to a combined loading. Modern protective structure components tend to be more flexible and lightweight than traditional fortified structures (i.e., concrete structures). They can undergo large plastic deformations without experiencing a material fracture. The structural response of such components under the combined effect of blast wave loading and fragment impacts is therefore of interest [13; 14]. Several research efforts addressing this issue have been reported on thin-walled metallic plates [15; 16]. To address the problem of combined loading, the combined loading scenario is sometimes decomposed into two sequential loading events: fragment impact and subsequent blast loading. Given the complexity of the failure mechanisms related to the fragment impact itself and the diversity of its influence factors, it is often simulated by using plates with pre-cut defects. These demonstrate a reduced structural integrity due to fragment impact. This method allows the creation of specific geometries to be studied under exposure of the blast loading. [PERSON] et al. [17] studied low-strength thin steel plates with squares and circular pre-cut defects subjected to a rapid change in pressure between the two plate sides. The pre-cut defects were symmetrically distributed around the center of each plate. It is emphasized that the spacing between the different pre-cut defects was kept constant in all experiments. The authors concluded that the pre-cut defects' shape, size, and number strongly affect the fracture resistance during blast loading. Moreover, they found that the smallest deflection is recorded for the plates with circular holes independent of the pressure loading. Inspired by these results, [PERSON] et al. [15] investigated the influence of different pre-cut geometries on the blast response of high-strength steel plates. The blast loading was generated by detonating varying amounts of TNT placed at a fixed distance from the plates. They observed that only plates with diamond-shaped defects fractured during testing. The plates with circular and square defects were indifferent to the various blast intensities. They concluded that a defect's shape alters the plates' resistance to fracture. [PERSON] et al. [16] investigated the blast response of thin aluminum plates with different pre-formed defects. They discovered that besides the defects' shape and number, both the orientation and spatial distribution significantly affect the fracture pattern and the plate's crack path. In the aforementioned studies, it should be highlighted that the pre-cut defects represent idealized geometries with no plastic deformation, as one would expect from a real fragment impact. Even though they may imitate the geometrical defects induced by a fragment impact, pre-cut defects do not represent the actual physics of the problem. When an actual fragment perforates a plate, material damage occurs in the proximity of the impact zone. An area of plastic strain is created around the hole with sharp notches and pethallingcracks. This amplifies the crack growth on the crack tip when the plate is exposed to a subsequent blast loading. Ignoring this phenomenon can lead to a non-conservative estimation of the actual fracture resistance under blast loading. To aid the design of protective structures, a limited number of studies were performed on blast-loaded plates perforated with real fragments. [PERSON] et al. [18] studied the effects of pre-cut circular holes compared with pre-formed ballistic impact on the dynamic behavior of thin steel plates exposed to blast loading. The plates were perforated using small-arm projectiles fired from a fixed rifle. Subsequently, they were loaded using a shock tube facility [19]. The pre-cut holes had the same circular shape and diameter as the ballistic impact holes.