Dynamic Mechanical Properties And Anti-ballistic Mechanism Of Carbon Fiber Composite Laminates

Carbon fiber reinforced composites(CFRP)have the characteristics of high specific strength,high specific stiffness,corrosion resistance and low density,and are widely used in aerospace,military protection,civil engineering and vehicle engineering.In practical applications,materials often need to withstand impact loads,such as bird strikes of aircraft structures,explosive effects of underwater mines on hulls,ballistic impacts of civil structures,and car collisions.In order to better evaluate the impact protection performance of CFRP,it is necessary to conduct in-depth research on its dynamic mechanical properties and ballistic resistance mechanism.In this paper,the static/dynamic mechanical properties of CFRP and the anti-ballistic properties of CFRP laminates with different structural forms are studied by combining theory and experiment.First,the static/dynamic mechanical properties of CFRP in the thickness and in-plane directions with the layup method of[-45/90/45/0]_s were systematically studied by using an electronic universal testing machine and a SHPB test device,and the stress-strain relationships at different strain rates in two directions are obtained.The theory of strain rate effect of brittle materials is introduced to explain the variation mechanism of CFRP dynamic compressive strength with strain rate in different directions.Observing the samples after the impact loading test revealed the dynamic failure mechanism of CFRP under different loading directions.Secondly,the ballistic gun test device was used to study the ballistic resistance of monolithic CFRP laminates with different thicknesses.Based on the cavity expansion theory and the Chen?Li(2003)model of the rigid projectile penetrating the target,the theoretical prediction of the ballistic limit and residual velocity of the spherical projectile impacting the CFRP laminate at high speed was completed,and the influence of the inertia effect of the target was analyzed.It shows that the theoretical analysis is in good agreement with the experimental data.Taking the ballistic limit as the limit,the projectile impact velocity is divided into two intervals,and the energy absorption mechanism and ballistic resistance of CFRP laminates with different thicknesses are analyzed.Combined with the projectile penetration process captured by the high-speed camera and the target failure form(including the impact surface,back and ballistic section),the failure mechanism of CFRP laminates with different thicknesses under the high-speed impact of the projectile is revealed.Finally,the composite structure of Al/CFRP/Al laminate was designed,the ballistic resistance test was carried out,and compared with the monolithic CFRP laminate of equal thickness,The ballistic resistance of two different structural targets under high-speed impact was analyzed,including ballistic limit,failure characteristics and energy absorption capacity,and the failure mechanism of the two structural targets was revealed from the perspective of stress wave propagation.The ballistic performance of Al/CFRP/Al laminates with equal thickness is better than that of monolithic CFRP laminates.