Manufacture of steel-CF/PA6 hybrids in a laser tape placement process: Effect of first-ply placement rate on thermal history and lap shear strength

This paper investigates the manufacture of selectively reinforced metal/composite hybrids in a laser-assisted automated tape placement process. Carbon-fibre/PA6 composite tapes were applied to PA6-coated steel substrates. The bonding of the first-ply to the substrate is critical to the success of the hybrid; the effect of first-ply placement rate was investigated for speeds of 25 mm/s, 50 mm/s, 100 mm/s. The interfacial bond strength of the hybrid laminates was determined by ASTM D 3165 lap shear tests. A 3D finite element thermal model was formulated to elucidate the thermal behaviour for increasing first-ply placement rate. A method for increasing model efficiency was shown to significantly decrease the computational difficulty while maintaining solution accuracy. Raising the first-ply placement rate from 25 mm/s to 100 mm/s resulted in a fourfold increase in lap shear strength with a maximum value of 22 MPa. The greater strength at higher speeds is attributed to improved synchronisation of the temperature and consolidation pressure history.