## 4 Conclusions  
The current study investigates the ballistic impact performance of 2D triaxial braided composite using three types of projectiles (gelatin cylindrical projectiles and CFRP and titanium-alloy blade-like projectiles) with similar masses and equivalent diameters for the casing containment application. Furthermore, impact tests of triaxial braided composites  
Figure 18: Enlarged view of local perforation damage to 2D triaxial braided composite target at different temperatures.  
were conducted at cryogenic and high temperatures considering the possible extreme working environment temperature. The current study aims to illustrate how projectile material and temperature affect the impact resistance of the composites. The main conclusions were drawn as follow:  
1. Given the fluid behavior of gelatin projectiles under impact load, the triaxial braided composite target impacted with a gelatin projectile undergoes global deformation and therefore absorbs much more energy than when impacted by CFRP or titanium projectiles. Upon impact with a gelatin projectile, delamination, matrix cracking, and slight fiber breakage appear in the through-thickness direction of the target.
2. Triaxial braided composites impacted by CFRP and titanium-alloy blade-like projectiles produce similar damage patterns. A rectangular opening appears at the impact surface and an elliptically shaped damage area appears at the exit surface with massive fiber breakage, yarn pull-out, and severe matrix cracking and delamination. The average energy absorption of the triaxial braided composite when perforated by a CFRP projectile is 77.59% greater than that perforated by a titanium-alloy projectile. When the composite target is impacted by a titanium-alloy projectile, its main damage has a shear pattern, and barely global bending deformation occurs to dissipate energy. Therefore, the usage of composite fan blades is very important, because compared to titanium alloy blades, the application of composite blades could not only reduce the weight of the blade itself, but also further reduce the weight of the composite casing, which will bring enormous economic benefits.
3. Cryogenic temperatures deteriorate the impact resistance of 2D triaxial braided composite material while high temperature improves its impact resistance. This result is attributed mainly to the decreased flexibility of the 2D triaxial braided composite target plate at cryogenic temperature, which permits less global deformation under impact load. The temperature affects the damage pattern of the 2D triaxial braided composites. Therefore, in the design and analysis of the composite containment casing, it is necessary to consider the influence of the working environment temperature.  
Conceptualization, L.L. and W.C.; methodology, L.L. and S.Y.; software, Z.Z. and G.L.; validation, L.L. and S.Y.; formal analysis, S.Y.; investigation, L.L.; resources, G.L.; data curation, Z.Z.; writing--original draft preparation, S.Y. and L.L.; writing--review and editing, L.L.; visualization, Z.Z.; supervision, W.C.; project administration, W.C.; funding acquisition, L.L. and W.C. All authors have read and agreed to the published version of the manuscript.  
This work was supported by the National Natural Science Foundation of China (Grant numbers 51975279 and 51605218) and the National Science and Technology Major Project [2017-IV-0006-0043].  
The authors would like to thank undergraduate students [PERSON] and [PERSON] for the help in the testing procedure.  
The authors declare no conflict of interest.