## 2 DIC Used in Impact Studies to Measure Target Deformation
The composite panels were made of phys in an arrangement of [(45\({}^{\circ}\)/90\({}^{\circ}\)/-45\({}^{\circ}\)/0\({}^{\circ}\))\({}_{3}\) / (0\({}^{\circ}\)/45\({}^{\circ}\)/90\({}^{\circ}\)/-45\({}^{\circ}\))\({}_{3}\)]. Two projectile speeds were undertaken, a high energy impact velocity of 134.3 \(\pm\) 1.7 m/s and a low energy impact test of 76 \(\pm\) 1 m/s. The projectiles the authors used were cylindrical, with a hemispherical nose, a diameter of \(24.9\pm 0.1\) mm, and made of an aluminium alloy. The high-speed tests were undertaken to measure the specific energy absorption of the panels, by looking at the residual energy of the projectiles after perforation. The authors undertook the low-speed tests to measure the full field deformation and major in-plane strains for non-penetrating impacts. The authors show that the durations of the impact were identical for all of the low-speed impacts, with the neat epoxy (no nano-modification) having the most compliance and showing the greatest strains. The neat epoxy also retained the largest residual strain at the end of unloading, implying the greatest permanent damage. For the high-speed impacts, the authors show that all of the nano-modified panels recorded exit velocities lower than the neat epoxy panel. The panel with a mix of epoxy, boron nanotubes and graphene nano-platelets performed the best, with a reduction in exit velocity of 89.1% [30]. [PERSON] et al. [31] used a single Shimadzu HPV-X camera (Shimadzu, Kyoto, Japan) running at 5M and 10M FPS to perform 2D DIC on two dynamic Brazilian test performed in split Hopkinson pressure bars. The authors reported on five different kinematic fields; displacement, velocity, acceleration, strain and strain rate fields. Brazillian tests enable the tensile strength of brittle materials such as concrete and rocks to be assessed. The authors used a 72 mm diameter and 10 mm thick disk made of ductal concrete, loaded to failure under impact, for each test. The speed of the input bar of the Hopkinson bar was about 6 m/s. Their first set of experiments used 5M FPS and demonstrated the reduction in displacement and strain uncertainty by using spatiotemporal DIC, rather than instantaneous DIC, was rather small, \(\sim\)4 times, but reduced significantly more for velocity and strain rate (\(\sim\)4\({}^{3}\)) and even more for the acceleration (\(\sim\)4\({}^{5}\)). The authors show that the second set of experiments, utilizing the cameras at 10M FPS, produced results consistent with the first experiment [31]. [PERSON] et al. [32] published their initial findings of a set of experiments comparing carbon fibre (CF)/epoxy and CF/poly(ether-ether keytone) (PEEK), in both drop rig tests and gas gun tests. The authors utilized 3D DIC in the gas gun tests, to determine BFD during the impact event. The high-speed photography was taken with two Phantom Miro M/R/LC310 cameras (Vision Research Inc., Wayne, NJ, USA), running at 29,000 FPS. The low-speed tests utilized a 12.7 mm diameter instrumented steel impactor, with a mass of 5.37 kg. The authors utilized a catching mechanism to prevent a second strike after rebound. The projectile for the high velocity tests was a hemispherical 12.7 mm diameter aluminium alloy projectile. The authors plotted the loads experienced during the drop tests, with each sample experiencing an initial increase in load due to the elastic response of the material, then a decrease in load, indicating initial damage, before a rise to maximum load. After the initial damage has occurred, the authors recorded the propagation of delamination, and matrix cracking from the initial damage. After the maximum load, the impactor rebounds, leading to a smooth decrease in the load. The authors reported that the load at the initial damage was relatively independent of the impact energy level. The CF/PEEK composites showed higher peak load than the CF/epoxy for all impact energy levels. The CF/PEEK also demonstrated less damage than the CF/epoxy specimens.