Similarly, [PERSON] et al. [19] examined the influence of foam filling in corrugated sandwich steel structures. They used a syntactic foam as filler and tested the influence of temperatures up to 900 \({}^{\circ}\)C. The foam-filled corrugated panels showed superior blast mitigation to the unfilled panels at room temperatures, while the increased temperature caused larger back face deflections and some core separation. The influence of graded density cores for sandwich panels subjected to blast loading has also been investigated by [PERSON] et al. [20] and [PERSON] et al. [21]. Based on the experimental results, it was concluded that grading the core density mitigated the through-thickness crack propagation and damage in the higher density foam layers. [PERSON] et al. [22] simulated blast loading by firing an aluminium foam projectile at sandwich structures with aluminium skins and a PVC core, and evaluated different foam densities and core thicknesses in terms of energy absorption efficiency. Low density foam cores with large thicknesses were seen to have excellent energy absorption abilities, but also thin high-density cores could be efficient when subjected to intensive impulses. An optimal core gradation was found to give beneficial blast mitigation when [PERSON] et al. [23] investigated the performance of sandwich panels with metallic skins and both graded and ungraded PVC foam cores under blast loading. The panel system with a low-density (large thickness) core appeared to be favourable for the mitigation of back face deformation and core cracking failure, and an optimal gradation of densities for the given problems was found. However, an optimal core gradation in terms of face sheet deformation and core cracking failure led to the risk of delamination failure of the core. Different face-sheet materials and a graded foam core were used for the sandwich panels subjected to blast loading by [PERSON] et al. [24]. They concluded that the blast resistance of sandwich panels with a positive gradient of the core density, i.e., a linear decrease in core density with blast direction, was superior to those with a uniform or a negative gradient of the core density. These and similar findings show that it is not straightforward to optimise such components experimentally and that simulation-based design optimization is required to make progress. A hybrid evolutionary optimisation algorithm for sandwich panels to maximise their blast mitigation was recently proposed by [PERSON] et al. [25]. In this study, the dynamic response of sandwich panels subjected to air-blast-like loading has been investigated both experimentally and numerically. The main objective of this work is to provide high-precision experimental data, combined with a validated numerical modelling strategy, that can later be used in simulation-based optimisation of sandwich panels exposed to blast loading. In the experimental tests, the blast load was generated using a shock tube facility, where the blast intensity could be accurately controlled and consistently repeated [26]. The experimental setup also facilitates reliable measurements of the in-situ response of the test components. Sandwich panels with 0.8 mm thick aluminium skins and a 50 mm thick polymeric foam core were subjected to different blast load intensities. The core material of the sandwich panels consisted of extruded polystyrene (XPS) with three different densities, i.e., 33, 37 and 50 kg/m\({}^{3}\). The quasi-static compressive properties of the polymeric foam cores have been extensively characterised in a previous work [6], while in the present study low-velocity impact tests on XPS foam samples were conducted and used for validation and calibration of a viscoplastic extension of the Deshpande-Fleck crushable foam model implemented as a user-material subroutine in LS-DYNA (R10.0, Livermore Software Technology (LST), Livermore, CA, USA, 2018) [27].