## 2 DIC Used in Impact Studies to Measure Target Deformation
The authors used a mirror behind the target to prevent damage to the two Phantom v7.11 cameras (Vision Research Inc., Wayne, NJ, USA) that were used to measure the BFD. The authors also used a Shimadzu HPV-X2 camera (Shimadzu, Kyoto, Japan), placed laterally to the target. This camera was used to record the evolution of the impact triangle and to measure the residual velocity of the projectile, if it perforated the target. The projectiles used were a 0.30 caliber fragment simulating projectile, fired at between 265 m/s and 1050 m/s to determine the V50 of the composite laminates. The authors show that the 25.4 mm carbon fibre panels impacted at 362 m/s showed a BFD of 0.45 mm at 38 us after impact. In comparison, the maximum deflection was 4.5 mm for an impact speed of 848 m/s. The maximum displacement results shown for the 3D DIC and the Shimadzu cameras were very similar (4.5 mm and 5 mm, respectively), with the small difference being attributed to frame rate difference or measurement accuracy. The 25.4 mm thick 2D panel exhibited a V50 of 1050 \(\pm\) 106 m/s, with the 6.35 mm thick 2D panel exhibiting a V50 of 282 \(\pm\) 73 m/s. The 3D composite panels exhibited similar V50 to the 2D panels with the same thickness, but the authors did exhibit about 70% smaller damage areas, leading to greater damage tolerance [28]. [PERSON] et al. [29] examined a number of novel multi-layered architectured ceramics, laminated together to enhance damage tolerance. Each ceramic tile was made from 263 borosilicate ceramic with 96-99.8% theoretical density, 3875 kg/m\({}^{3}\) density and a thickness of 0.635 mm. The authors created three different designs for the panels. The designs consisted of (i) hexagonal tiles with three different characteristic lengths (L\({}_{1}\)), (ii) parallel cut tiles with two different spacing lengths (L\({}_{2}\)) to develop multilayered cross ply (4 layer) and bouligand (8 layer) ceramic panels and (iii) a shell like design with a combination of hexagonal and plain configuration. All of the tiles were bonded together using Surlyn adhesive, as it provides an elastomeric response with a strain stiffening mechanism at the interfaces. This delays localization fracture and distributes the deformation throughout the material. The authors performed both quasi-static and impact tests on the architectured ceramics, with the side opposite the load or strike face being speckled to allow for DIC. For the quasi-static tests, the authors used two five-megapixel cameras (FLIR Grasshopper3, Systems, Inc., Wilsonville, Oregon, USA), illuminated with a high intensity LED light. The imaging for the impact testing was accomplished using two one-megapixel cameras operating at 20,000 FPS, and this imagery was processed to obtain the deformation and strain fields. Both the quasi-static and impact tests were performed three times in different locations near the centre of the tiles, ensuring the hit locations were the same between tile samples. The impact testing was conducted with a 14 J low velocity impact (2.1 m/s impact velocity). The authors show that smaller hexagonal tiles (L\({}_{1}\) = 2.5 and 5 mm) with lower stiffness increased the multi-hit capability, absorbing more energy in the second and third hit than any of the other arrangements. However, decreasing tile size does lead to larger delamination and greater deflection [29]. [PERSON] et al. [30] examined, using 3D DIC, the full field deformation and major in-plane strains of glass fibre reinforced polymer laminates with a nano-modified epoxy matrix. The 3D DIC was conducted with two Phantom Miro M/R/LC310 high-speed cameras (Vision Research Inc., Wayne, NJ, USA) at a frame rate of 39,000 FPS and the imagery was processed using the ARAMIS commercial software. The epoxy matrices were modified by including graphene nanoplatelets, multi-walled carbon nanotubes, multi-walled boron nitride nanotubes or hexagonal boron nitride particles.