Low‐velocity impact damage and compression after impact behavior of CF/PEEK thermoplastic composite laminates

Abstract

Impact resistance and damage tolerance are of great significance in the design of composite structures. This study researched the damage and failure mechanism of carbon fiber reinforced poly-ether-ether-ketone (CF/PEEK) composite laminates under the low-velocity impact (LVI) and compression after impact (CAI) loading conditions. The test included four impact energy levels (15, 30, 45, and 60 J) and compared the effect of two different stacking sequences ([0 /90 ] 8S and [0 /45 /90 /À45 ] 4S ) on performance. The results shown that the peak impact force of the two different stacking sequences increased from 7.8 kN/8.3 kN-11.4 kN/13.7 kN, and the CAI strength decreased from 370.5 MPa/419.3 MPa to 212.8 MPa/232.5 MPa, respectively. Nondestructive testing of low-velocity impact specimens by ultrasonic C-Scan was employed to investigate structural damage. Digital image correlation (DIC) was employed to perform full-field displacement measurements for the CAI experiment. The cross-section of typical specimen was observed using a scanning electron microscope (SEM) to determine the failure mode of the specimen. In addition, a 3D damage model based on continuum damage mechanics was established, with the consideration of the interlaminar delamination damage and intralaminar damage. Compared with the experimental results, the errors of the numerical simulation of the peak impact force, impact energy absorption, and CAI strength are 3.8%-14.8%, 3.7%-6.9%, and 2.2%-6.7%, respectively, which verifies the validity and rationality of the model. Furthermore, the numerical model and interpolation function were used to predict the ultimate residual strength.

Experimental investigation of impact resistance and compression behavior of CF/PEEK laminates after hot‐press fusion repair with different stacking sequences

“…For the specimens SS1 and SS2 used in this study, the experimentally measured S u are 381 and 441 MPa, respectively. 37 As shown in Figure 10B, a higher impact energy resulted in a lower normalized residual strength, and it can be observed that the rate of decline slowed down. The increase ratio of normalized residual strength for SS1-IAH and SS2-IAH specimens, which were subjected to various energy levels, ranges from 22.1% to 31%.…”

Residual compressive strength of polyamide fiber‐reinforced epoxy composites after low‐velocity impact

“…They also emphasized that TR‐CFRP has less delamination than R‐CFRP. Liu et al [ 36 ] investigated the damage and failure mechanisms of carbon fiber reinforced poly‐ether‐ether‐ketone (CF/PEEK) composite laminates subjected to LVI and CAI loading. Simulating the LVI and CAI properties of composite laminates, they developed a three‐dimensional finite element model based on continuous damage mechanics.…”

Tensile behavior of the bolt‐jointed GFRP after low‐velocity impact

“…As a result, regarding various types of composite laminates, many studies have been carried out to illuminate the impact damage mechanism as well as the deep negative effect of the LVI on the subsequent mechanical properties such as tensile test, [10] shearing, [11,12] bending [13][14][15][16] and compressive test. [17][18][19] The part of existing latest related research and their research contents are summarized and the first point to note is that even a tiny impact energy can lead to a significant decrease in the strength under various kinds of post-impact tests. In addition, the effect of LVI load on the post-impact behavior depends on a combination of multiple factors, such as original materials, the configuration of the specimens, and even size, and so forth.…”