Novel method of producing in-plane fibre waviness defects in composite test coupons

The in-plane fibre waviness defects that can occur during tape laying of carbon fibre reinforced prepreg materials can have significant adverse effects on their resultant mechanical properties. Therefore, it is necessary to produce coupon test specimens containing such defects. A novel hot air gun and plastic rod pull-through method was developed to fabricate tension test coupon specimens with varying levels of in-plane fibre waviness defects using Hexcel M56/IM7 carbon fibre prepreg. Wave severities (defined as amplitude/wavelength) ranging from 0.040 to 0.066 were produced. Compared with control specimens without fibre waviness, the presence of in-plane wave defects reduced the ultimate tensile strength and tensile modulus by up to 52% and 30%, respectively. Increasing the severity of the wave defects typically decreased tensile performance. Failure of the specimens was observed to occur at the location of the wave defect.