Structural performance of the glass fiber–vinyl ester composites with interlaminar copper inserts

Mechanical performance in tension, compression and flexure of glass fiber reinforced vinyl ester composites with interlaminar copper inserts was evaluated experimentally. Key variables in performance evaluation were relative size of the copper insert and surface treatment of copper. Test coupons were manufactured using VARTM method and tested following ASTM standards for tension, compression and flexure (four-point bend). Process-induced residual strains were measured during fabrication and proved to have minimal impact for the specific thermal cycles involved. Mechanical test results indicate that the change in insert size or surface treatment have minimal impact on tensile properties though the presence of copper inserts increases failure strain. Both insert size and surface treatment have a strong impact on compression and flexural properties associated with compression mode. Decrease in mechanical properties under compression and flexure are mainly due to poor adhesion between the copper surface and the composite and the resulting delaminations. For composites with large inserts, compatible surface treatments restored both compression and flexure properties to the equivalent baseline (no copper insert) performance.