# Dynamic Response of Copper Plates Subjected to Underwater Impulsive Loading
## 1 Introduction
reported the structural response of thin steel and aluminum plates with different stand-off distances under air blasting [19]. These experimental investigations showed that thin plates experienced larger plastic deformation and the failure of supports. [PERSON] et al. investigated full-field transient plate deformation measurements during buried blasting loading using the 3D DIC method. They well-defined yield boundaries on the plate surface were based on the Cowper-Symonds constitutive relation, with full-field strain and strain rate measurements [20]. [PERSON] et al. obtained blast-driven displacement measurements of an aluminum 6061-T6 plate as one side of an aquarium-like structures using a DIC system [21]. [PERSON] et al. used high-speed photography and the DIC method to monitor the deformation and reveal the failure mechanism of glass-fiber reinforced polymer (GFRP) sandwich panels and laminate tubes during underwater shocks [22]. [PERSON] and [PERSON] carried out experimental and numerical investigations on the transient response of e-glass/vinyl ester curved composite panels subjected to underwater explosive loading using a 3D DIC system, along with high-speed photography [23; 24]. Similar investigations on aluminum honeycomb sandwich panels in FSI experiments were reported by [PERSON] et al. [25]. [PERSON] et al. performed an experimental study on dynamic deformation and failure modes of circular composite laminates, based on the processing of the 3D DIC method, and observed how the impulse intensity, thickness, and failure of panels clearly by affect the response of laminate plates [26]. [PERSON] et al. presented a comprehensive summary review of recent underwater implosion studies on metallic cylindrical structures. These studies demonstrated that the 3D DIC technique can be used for accurate dynamic deformation measurements during underwater implosion [27]. Recently, there is increasing interest in the dynamic response and failure at the supports of materials subject to shock loading, but only limited studies have reported on metal panel and composite materials' response to underwater impulses generated by FSI equipment. The microscopic damage mechanism of these materials under impact loading conditions is not well understood. The quantification of the response of these materials as a function of loading intensity has not yet been fully investigated. Studies on the effect of initial damage on failure modes of these materials to underwater impulses have been rarely reported. This paper presents the transient responses and failure modes of clamped copper plates subjected to underwater shock loading. The shock pressure histories generated in FSI apparatus' are well monitored. Two typical pre-notches are selected to evaluate the effect of pre-notches on the failure modes. A high-speed photography system with two cameras is applied to record real-time images of the copper plate. The time-resolved 3D full-field deformations are measured using the DIC technique. Visual observations and scanning electron microscope are carried out to identify the failure modes. A dimensionless deflection is performed to explain the effects of experimental conditions on the dynamic responses of circular plates subjected to underwater impulsive loading.