TY - JOUR
T1 - The effect of semi‑cured elements on the quality of integrated composite structures
AU - Radhakrishnan, Arjun
AU - Mavrogordato, Mark
AU - Zivkovic, Petar
AU - McMahon, Turlough
AU - Kratz, James
N1 - Publisher Copyright:
© The Author(s) 2025.
PY - 2025/1/14
Y1 - 2025/1/14
N2 - There is a demand to ramp up the rate of production of primary aerostructures and as such new processing methods are required. This study investigates a two-stage process for integrating composite structures. In Stage 1, a series of doublers are infused and semi-cured to a target degree of cure (α). In Stage 2, these doublers are integrated into a preformed stiffened panel, to increase thickness locally, followed by infusion. The impact of this integration on quality in terms of thickness and void content of the semi-cured doublers is assessed through the processing stages. The results indicate that semi-curing elements to a higher degree of cure (α = 0.74) around the gel point (α = 0.70) of the epoxy matrix have minimal impact on the relative quality of the final structure. However, at a lower semi-cure (α = 0.47), the void (> 100 µm) content increased from 0.8 to 1.92% during the secondary stage. Tracking the thermal profile of the semi-cured elements through the stages combined with a Cure-Temperature-Transition diagram shows that at a lower degree of cure, the resin in the semi-cured doublers will be in a liquid phase during Stage 2 leading to the potential for resin reflow.
AB - There is a demand to ramp up the rate of production of primary aerostructures and as such new processing methods are required. This study investigates a two-stage process for integrating composite structures. In Stage 1, a series of doublers are infused and semi-cured to a target degree of cure (α). In Stage 2, these doublers are integrated into a preformed stiffened panel, to increase thickness locally, followed by infusion. The impact of this integration on quality in terms of thickness and void content of the semi-cured doublers is assessed through the processing stages. The results indicate that semi-curing elements to a higher degree of cure (α = 0.74) around the gel point (α = 0.70) of the epoxy matrix have minimal impact on the relative quality of the final structure. However, at a lower semi-cure (α = 0.47), the void (> 100 µm) content increased from 0.8 to 1.92% during the secondary stage. Tracking the thermal profile of the semi-cured elements through the stages combined with a Cure-Temperature-Transition diagram shows that at a lower degree of cure, the resin in the semi-cured doublers will be in a liquid phase during Stage 2 leading to the potential for resin reflow.
KW - Parital curing
KW - Composite structures
KW - Aerostructures
KW - Staged-curing
KW - Modified Co-curing
KW - Integrated structures
KW - Composite Joining
KW - High-rate manufacturing
U2 - 10.1007/s00170-025-15002-2
DO - 10.1007/s00170-025-15002-2
M3 - Article (Academic Journal)
SN - 0268-3768
VL - 136
SP - 2757
EP - 2768
JO - International Journal of Advanced Manufacturing Technology
JF - International Journal of Advanced Manufacturing Technology
IS - 5
ER -