Dynamic failure of composite strips under reverse ballistic impact. (15th November 2022)

• Record Type: Journal Article
• Authors: Gao, Jinling; Kedir, Nesredin; Hernandez, Julio Andres; Zhou, Fengfeng; Tsai, Jung-Ting; Tallman, Tyler N.; Jun, Martin Byung-Guk; Chen, Weinong
• Is Part Of: International journal of mechanical sciences. Volume 234(2022)
• Publication Date: 2022-11-15
• Subjects: Composite strip -- Projectile nose -- Reverse ballistic impact -- Wave propagation -- Local deformation; Mechanical engineering -- Periodicals; Génie mécanique -- Périodiques; Mechanical engineering; Maschinenbau; Mechanik; Zeitschrift; Periodicals; 621.05
• DOI: 10.1016/j.ijmecsci.2022.107700
• Languages: English
• ISSNs: 0020-7403

Abstract

Highlights: A reverse impact method was utilized to study the dynamic behavior of composite strips. Three failure modes were identified for the composite strips under ballistic impact. Experimental results were compared with Smith's theory. The effect of the projectile nose on the composite's failure behavior was studied. Stress concentration underneath the projectile should be considered in the modeling. Abstract: Mesoscale impact experiments on composite strips were conducted in this study to reveal the fundamental failure mechanisms of fiber-reinforced composites (FRCs) under transverse impact by different projectiles. The componential material of composite armor, S-2 glass/SC-15, was manufactured into a single ply and sectioned into strips. The strip specimens were first characterized by X-ray computed tomography and scanning electron microscopy (SEM). The impact experiments were performed using a light-gas gun, shooting the strip specimens to the static wedge-nose projectiles with different nose diameters of 4, 40, and 400 µm. A high-speed camera recorded the strip's failure process from the side. Such a reverse ballistic impact scheme enabled to focus the camera on the projectile nose where the strip was deformed and fractured so that the entire failure process was recorded in real time. These experiments identified three failure modes of the composite strip for each projectile type, defined by no, partial, and complete local failure by the impact loading. The critical velocity region was quantified, showing rising upper and lower boundaries corresponding to the projectile nose diameter. The experimental data were compared with theoretical predictions by Smith's theory. The transverse wave speed deviated from Smith's prediction as the projectile nose diameter decreased, demonstrating a possibly significant error when the pure-tension assumption is employed to model the composite's impact behavior by sharper projectiles. Besides, a sharper projectile was more likely to induce a smaller tent angle, indicating a larger local deformation, considered owing to the stress concentration at the projectile nose. Graphical abstract: Image, graphical abstract