Damage analysis of carbon fiber reinforced aluminum laminate under short beam and single edge notch beam bend test

Abstract

In the present study, the carbon fiber aluminum laminates were fabricated in two configurations Al/0°/Al/0°/Al/0°/Al/0°/Al, Al/0°/Al/90°/Al/90°/Al/0°/Al (represented as Carall 1, Carall 2 respectively) after different surface modifications employed to AA2024-T3 sheets. The influence of surface modification on interlaminar shear strength (ILSS) was investigated by short beam shear (SBS) test for each configuration with different span to depth ratio. The Caralls fabricated by abrasion of 220 grit size paper show maximum apparent ILSS than other surface modifications due to the better mechanical interlocking at the interface. The measured apparent ILSS is about 35% higher than only anodized treatment. The finite element (FE) simulation reveals in both laminates the failure is initiated by inter laminar delamination near the mid span of the laminate. The position of the crack in Carall 1 is at the innermost interface however in Carall 2 at the outermost interface. In the later stage of SBS tests multiple delamination followed by matrix cracking leads to final separation of the laminate layers. Further, the full field strain in the neighbourhood of notch during single edge notch beam bend (SENB) test was evaluated using the digital image correlation technique supported by FE simulation. Carall 1 treated with 220 grit paper shows 46% more plane strain fracture toughness than AA2024-T3 and about 10% improvement than anodized treatment attributed to crack bridging and improved inter laminar strength. The improvement of toughness significantly reduces for Carall 2 and maximum 13% improvement is noticed for Carall 2 treated with 220 grit papers for improved inter laminar strength.