Mode II interlaminar fracture toughness enhancement of fine z‐pin reinforced carbon fiber composite with low fraction of pins

Abstract

This article aims to improve the shear delamination resistance of composite laminate and minimize implantation damage on fiber orientation by using fine z-pins.The z-pins with the diameters as small as 0.1 and 0.2 mm were prepared by using different carbon fibers. The results show that z-pinning method significantly improves the mode II interlaminar fracture toughness, and the G IIC value becomes larger with the decrease in z-pin diameter. Compared with the control sample, the precracked G IIC values of (carbon fiber-reinforced polymer composite) CFRP (0.5CF4XÀpin) , CFRP (0.2CF4XÀpin) , and CFRP (0.1CF4XÀpin) increase by 67%, 142%, and 176%, respectively. As z-pin diameter decreases from 0.5 to 0.1 mm, the failure mode changes from z-pin pullout to shear fracture. The evolution of failure mode greatly enhances the resistance to crack propagation and the final G IIC value. The carbon fiber type of pin (0.5mm) has no obvious influence on the delamination sliding resistance. For pin (0.1mm) and pin (0.2mm) , the strong deformation resistance of z-pin is the dominant factor driving the improvement of the G IIC values though providing high-shear traction load. In addition, the z-pins with large shear deformation capacity can also enhance the crack sliding resistance.

Experimental evaluation on the synergistic effect of PC/ABS/DGEBA blend in fracture toughness enhancement of CFRP composites at cryogenic temperatures

“…CFRP laminates are used in many applications where high specific strength materials are required 1–4 . The brittle nature of the thermoset epoxy matrix inherited by CFRPs and the high chances of delamination in laminate layers of composite 5 limits its use in many applications, particularly those requiring cryogenic performance 6,7 . Fiber/matrix modifications improve fracture toughness, 8 reduce delamination 9 and brittleness, and increase resistance to microcracks, 10,11 pushing the use of CFRPs even further.…”

Low‐velocity impact response and post‐impact assessment of self‐healing composites with different stacking configurations of core–shell nanofibers

“…However, CFRP still has weaknesses, including poor interlayer toughness due to the lack of z-directional toughening and a unique laminated structure that is susceptible to out-of-plane loads. [1][2][3][4] For instance, low-velocity impact (LVI) is a major issue, and this type of damage can cause invisible damage to the material, such as matrix cracking, microcracking, and internal delamination. [5][6][7][8][9][10] In addition to affecting the structure's strength, durability, and stability, these defects are frequently difficult to detect and repair.…”

“…Due to their high‐specific mechanical properties and designability, carbon fiber‐reinforced polymer (CFRP) matrix laminated composites have garnered a great deal of interest and are increasingly used in the aerospace, marine, and automotive industries as high‐performance structural materials. However, CFRP still has weaknesses, including poor interlayer toughness due to the lack of z ‐directional toughening and a unique laminated structure that is susceptible to out‐of‐plane loads 1–4 . For instance, low‐velocity impact (LVI) is a major issue, and this type of damage can cause invisible damage to the material, such as matrix cracking, microcracking, and internal delamination 5–10 .…”

On the interlaminar fracture behavior of carbon/epoxy laminates interleaved with fiber‐hybrid non‐woven veils

“…4 A significant amount of research attention has been paid to improving the interlaminar fracture toughness of conventional composite laminates in the last two decades. [5][6][7][8][9] Various extrinsic or intrinsic toughening methods have been developed for the modification of the interlaminar fracture behavior such as through-thickness reinforcement techniques (e.g., z-pinning [10][11][12][13] ), matrix toughening methods by adding various fillers (e.g. core-shell rubber 6,14 ) and interleaving various materials (e.g., veils [15][16][17][18] ).…”