• An improved 3D-LTCA method was developed to account for gear tooth modification and coupling assembly errors, with mesh stiffness verified against MASTA software.
• A neural network-based surrogate model accurately maps the relationship between modification parameters and mesh mechanical parameters, drastically reducing computational cost.
• The optimization framework minimizing mesh stiffness variation and improving load distribution reduced mesh stiffness fluctuation by 34.10% under assembly errors.
• The difference in average contact stresses between left and right mesh surface regions was reduced by 62.84%, demonstrating enhanced mesh uniformity and stability.