Mechanical response and damage evolution of CF/PEEK‐reinforced Al metal‐composite hybrid structure at high strain rate

Abstract

AbstractA CF/PEEK‐reinforced Al metal‐composite hybrid structure (CF/PEEK/Al) and CF/PEEK bar were subjected to high strain rate compression tests with a split Hopkinson pressure bar (SHPB). With the increase in strain rates, both CF/PEEK and CF/PEEK/Al showed the strain rate strengthening effect, and the microscopic fracture surface of CF/PEEK changes from rough to smooth. In the plastic rheological stage of stress–strain curve, CF/PEEK shows a plateau effect, while CF/PEEK/Al shows the strain weakening effect. When the strain rate exceeds 3800 s−1, the stress–strain curve exhibits a secondary wave peak. The peak values of the secondary peak in CF/PEEK/Al are larger than CF/PEEK. In terms of peak stress, yield stress, and specific energy absorption, CF/PEEK/Al outperforms CF/PEEK. Compared with other structures, the CF/PEEK/Al metal‐composite hybrid structure has certain advantages in terms of yield strength and yield strain. The finite element method (FEM) and DIC system were applied to observe the dynamic damage process in the compression impact test. It was found that in CF/PEEK/A1, the Al thin‐walled tube was damaged and cracked at the contact interface, and the inner CF/PEEK began to be damaged at the contact center with the input bar. And at 335 μs after contact began, the shear band ran through to the side of the samples.Highlights A CF/PEEK‐reinforced Al metal‐composite hybrid structure (CF/PEEK/Al) was proposed, which is superior to CF/PEEK. When the strain rate exceeds 3800 s−1, the stress–strain curves of CF/PEEK and CF/PEEK/Al exhibit a secondary wave peak. The peak values of the secondary peak in CF/PEEK/Al are larger than CF/PEEK. With the increase in strain rates, both CF/PEEK and CF/PEEK/Al showed the strain rate strengthening effect, and the microscopic fracture surface of CF/PEEK changes from rough to smooth. In CF/PEEK/A1, the Al thin‐walled tube was damaged and cracked at the contact interface, and the inner CF/PEEK began to be damaged at the contact center with the input bar. And at 335 μs after contact began, the shear band ran through to the side of the samples.