Exploring the mechanical behavior of nozzle CFRP/Al support structures via multi-physics modeling

The mechanical behavior of the nozzle CFRP/Al support structure was investigated using a multi-physics modeling approach. A sequentially coupled thermochemical-mechanical model was developed to capture the curing behavior of CFRP composites. The temperature and degree of cure (DoC) profiles were obtained and used to predict the evolution of mechanical properties, cure-induced residual stress (CRS) and deformation. The post-cure configuration was then imported into the mechanical analysis of hybrid CFRP/Al structures, to account for the cure-induced effects. Axial tensile tests were conducted experimentally and numerically on CFRP/Al bolted joints. The prediction errors in joint stiffness and strength remain below 8% with varying tightening torques, validating the reliability of the modeling approach. Subsequently, the mechanical behavior and damage mechanisms of the nozzle CFRP/Al support were explored under combined pressure-bending loads. The dominant damage modes are characterized as matrix cracking in the CFRP shell and ductile damage in the Al liner. Finally, a parametric study was carried out to assess the effects of holding temperature, dwell time and tightening torque on the load-carrying capacity. It reveals that extended dwell time promotes the cure process and enhances the structural strength. In contrast, moderate increases in holding temperature and tightening torque benefit the structural performance, while excessive values result in performance reduction.