Damage behavior in quasi-isotropic CFRP laminates with small fiber orientation angle mismatch

Abstract

The use of carbon fiber reinforced plastic (CFRP) has contributed in producing light-weighted and strong aircraft structures. However, the low impact resistance of CFRP makes it easier for internal damages to occur. By using thin-ply prepeg with thickness of less than 0.05 mm, laminates with smaller differences in fiber orientation angle and with the same thickness as the conventional laminates can be formed. This study investigates and compares the mechanical properties and damage behaviours between quasi-isotropic laminates with fiber orientation angle mismatch of 45 degrees (45QI) and laminates with small fiber orientation angle mismatch of 15 degrees (15QI). Both laminates are loaded in tension in 0, 7.5, 15 and 22.5 degrees. Low velocity impact tests are also conducted. From tensile testing, 15QI laminates shows more isotropic properties in strength than 45QI. Damages were observed by using microscopic and X-ray images. Crack propagation in width direction can be prevented in 15QI laminates. From low velocity impact testing, we understand that impact responses are not depending so much on the fiber orientation angle mismatch. In terms of internal damage, 15QI laminates has smaller delaminated area near the impact point compared to 45QI laminates.

Keywords

• carbon fiber reinforced plastics
• quasi-isotropic
• thin-ply prepreg
• orientation angle
• tensile loading
• low-velocity impact
• delamination
• damage behavior