Tolerance-Driven Lightweight Design and Interface Mechanical Robustness Study of Multi-Material Coupled Structures for Aircraft Horizontal Tail

Addressing the coupled challenges of lightweighting and stiffness preservation in aircraft horizontal tail structures, this study proposes a multi-material asymmetric distribution strategy integrating carbon fiber reinforced polymer (CFRP), closed-cell foam cores, and aluminum alloy joints. A 3D nonlinear finite element model incorporating adhesive layer thickness variations and foam density fluctuations was developed to quantitatively characterize the sensitivity of interfacial mechanical properties to manufacturing tolerances. Results demonstrate that the co-optimized structure achieves a single-wing weight of 17.8 kg (32% reduction versus all-metal designs) with maximum displacement constrained to 188.8 mm. A 0.2 mm reduction in adhesive thickness elevates interfacial shear stress peaks by 22%, with Monte Carlo analyses confirming that adhesive thickness variability accounts for 64% of displacement variance. Through ±45° ply reinforcement and tolerance-driven robustness optimization, displacement standard deviation was reduced by 50% while transverse shear modulus increased by 17.3%. Scaled prototype testing validated that gradient density compensation strategies further reduced displacement response variability by 41%, with the calibrated model achieving a coefficient of determination (R²) of 0.96 against experimental data. This work establishes a quantitative process-structure-property mapping framework, providing methodological support for reliability-oriented design of multi-material aerostructures.