## 3 3D DIC in Blast and Shock Loading
The authors used the 3D DIC to examine the evolution of the transient out-of-plane deformation profile of the plate and the transient deformation time history of the midpoint of the plate. The initial deformation appears to be localized to a plastic hinge in the centre of the plate. As time progresses, the plastic hinge moves outward to the clamp frame, with a conical section between the midpoint and the plastic hinge. The next stage is the plate forming into a general bell shape with a point of inflection around 100 mm diameter. By the time the plates have reached their maximum deflection, the point of inflection has become less significant and is almost undetectable by the time the plate reaches its final shape. The displacement histories produce very similar profiles at each charge mass. An important observation is that during the transient deflection, the profile does not match the shape of the final deformed shape at any point. The strain measured by the 3D DIC shows that the strain is localized to the centre of the plate, peaking at the centre of the plate and decaying to a very small value approximately 1/6 th the plate diameter from the centre. The minimum strain coincides with the point of inflection in the permanent deflection profile. The maximum strain increases with an increase in charge mass and decrease in standoff distance [59]. [PERSON] et al. [60] examined displacement measurements of submerged implodable volumes. Implodable volumes are defined as any structural shell or body that is acted on by an external pressure and contains internal gas at a lower pressure (or vacuum). As a submerged body implodes the acquired momentum of the in-rushing water causes it to over-compress against the structure and produces strong outwardly radiating shockwaves. [PERSON] et al. examined three cases, a free-field implosion caused by increasing pressure, a semi-confined implosion caused by increasing pressure or explosive initiation, and a closed, confined tube implosion initiated by explosive. The authors used a pair of Photron SA1 cameras (Photron USA, Inc., San Diego, CA, USA) operating at 30,000 FPS to obtain the 3D DIC imagery. The deformations, strain and strain rate were calculated from the imagery through the VIC-3D version 7 (Correlated Solutions, Inc., Irmo, SC, USA). The accuracy of the 3D DIC in an underwater environment was calibrated in a custom designed tank. [PERSON] et al. showed results from a seamless tube of aluminium 6061-T6 grade, with ends sealed by hemispherical caps. The authors show that the deformation of the specimen begins at the centre and symmetric about the mid-plane. The 3D DIC shows that the centre of the specimen reaches a maximum wall velocity of ~25 m/s and leads to a substantial rate of change in the volume of the specimen. The contact of the two opposite walls moves towards each other with a relative velocity of ~50 m/s and the impact between the two solid surfaces leads to strong sound waves, manifesting as a short duration shock pulse in the water. Their results show that this contact propagates towards the direction of the end-caps with high velocity (~100-200 m/s). In comparison, the case where the implodable volume is contained within a semi-confined tube, the walls only reached a maximum wall velocity of ~12 m/s and a collapse front velocity of ~70 m/s. This decrease is due to the limited amount of potential energy in the limited amount of fluid around the implodable volume. In the case where the implosion was initiated by an explosive, it caused cavitation along the confinement walls, causing various bubble cycles. The high pressure from the first bubble collapse supplies sufficient energy to the specimen to make it unstable and collapse. As there is less potential energy in the surrounding fluid, the walls start with a collapse velocity of ~12 m/s, but slow to 8 m/s before contact with the opposite wall. [PERSON] et al.