Effect of polyurea interlayer on ballistic performance of ceramic armor module against long rod impact

• Main Author: Luo, Boyang
• Other Authors: Chen Zhong
• Format: Thesis-Master by Research
• Language: English
• Published: Nanyang Technological University 2021
• Subjects: Engineering::Materials
• Online Access: https://hdl.handle.net/10356/145914
• Institution: Nanyang Technological University

Improvement of ballistic resistance of ceramic armour against long rod impact is of great interest to armor designers and researchers. Spray-coating of a layer of polyurea on the front and/or back surfaces of metallic armor have been widely investigated to improve the protective performance of the metallic armor subjected to projectile impact. However, the study on the application of polyurea in ceramic armor for ballistic performance enhancement against long rod impact at high impact velocity (> 1000 m/s) is still lacking. This project investigates the effects of mechanical properties of polyurea on the ballistic resistance of ceramic armor modules against long rod projectile impact. The effects of the strength and thickness of polyurea on the ballistic resistance of ceramic armor modules were studied through experiments and numerical simulations. Two types of polyurea (PUK&PUD) were successfully synthesised in Ma Jan High-Speed Dynamics Lab. Quasi-static tensile, compression and shear tests were carried out to compare the mechanical properties of PUD and PUK polyurea. It reveals that PUK polyurea has a higher yield strength of 10 MPa and lower elongation of 360%. PUD polyurea has a lower yield strength of 0.8 MPa and higher elongation of 500%. Significant increment of shear stress and shear modulus were observed with applying compressive stress for both types of polyurea. This study investigated the effect of two primary factors of polyurea on the ballistic performance of ceramic armor modules; (1) strength of polyurea, (2) thickness of polyurea interlayer. The mass efficiency of ceramic target module increased from 1.59 to 1.85 when 2 mm PUK polyurea was used as an interlayer between ceramic and cover plate. In contrast, the mass efficiency decreases from 1.85 to 1.68 with reducing the flow stress of polyurea from 9.8 MPa to 1 MPa. The mass efficiency of ceramic armor module varies with increasing polyurea interlayer thickness from 0 to 6 mm. Ceramic armor module with 2 mm polyurea interlayer has the highest mass efficiency. The mass efficiency reduced with increasing the thickness of polyurea. Through these experiments, it can be concluded that: (1) polyurea could improve the ballistic performance of ceramic amour module by influencing the dwell time. (2) Polyurea with higher strength would have better ballistic performance. (3) The optimised thickness of polyurea interlayer is 2 mm. Simulations for the two types of polyurea under dynamic load were validated through the quasi-static test, SHPB test and ballistic experiment. It was found that the simulation model of the ceramic module with polyurea as an interlayer has acceptable accuracy. According to the simulation results, it has been confirmed that the polyurea interlayer could enhance the ballistic resistance of ceramic armor module by influencing the dwell time. With polyurea interlayer, the shock wave caused by projectile impacting ceramic tile can be attenuated. So the dwell time is increased with proper choice of the material and thickness.