Influence of fibre orientation,moisture absorption and repairing performance on the low-velocity impact response of woven flax/Elium ® thermoplastic bio-composites

The importance of natural reinforced bio-composite materials with desirable properties such as high modulus-to-weight ratio, good impact resistance, and the ability to be easily repaired is crucial in the industry. A woven flax/Elium^® thermoplastic bio-composite is manufactured to challenge these needs. Elium^® is the only resin that permits the manufacture of large parts with thermoset-like processes, as Liquid Resin Infusion presented in that work. The paper highlights the influence of stacking fibre orientation, moisture absorption, and repair aptitude on its impact resistance. An instrumented drop tower was needed to conduct low-velocity impact tests at several energies and high-speed image coupled with microscopic observations was used to assess the damage evolution. The impact resistance was improved for the dry (0/90)₆ orientation, but moisture absorption decreased its impact peak force by 20%. A three-point bending test was preferred to compression after impact for studying the residual properties after impact. The bio-composites with (±45)₆ orientation showed higher impact residual performance than the (0/90)₆ orientation, and corresponded to the reduction of maximum bending force by 20% than that of the reference. In addition, a thermo-compression process was applied to repair the impacted plates and conduct multiple impact/repair cycles which showed a significant recovery of stiffness and maximum impact force at 4J on (0/90)₆ plates, highlighting their potential for repair in the automotive and marine industries.