Although the dynamic response of orthotropic materials under uniaxial impact loading has been extensively studied, their behavior under multiaxial stress states, which more accurately represent real-world blast and impact scenarios, has received limited attention. To address this gap, this study employed a self-developed biaxial impact testing apparatus to systematically investigate the dynamic mechanical behavior of beech wood, a typical orthotropic material, under three biaxial loading configurations: radial-tangential, radial-longitudinal, and tangential-longitudinal. By combining theoretical derivation with experimental data, it systematically examines stress wave propagation characteristics, strain rate effects, and anisotropy evolution under different loading paths. The results reveal that beech wood exhibits significantly distinct dynamic responses along different material orientations, with a consistent strength hierarchy: longitudinal > radial > tangential. Biaxial loading notably enhances the equivalent stress–strain response and alters the deformation mechanisms and energy absorption behavior. Furthermore, lateral confinement and multiaxial stress coupling are identified as critical factors influencing the dynamic performance. This study provides the first systematic revelation of the strain rate strengthening mechanisms and wave propagation characteristics of orthotropic materials from the perspective of multiaxial dynamic loading, thereby offering theoretical and experimental foundations for developing advanced dynamic constitutive models suitable for complex impact conditions. These findings provide important guidance for the design and evaluation of lightweight impact-resistant structures in fields such as aerospace and protective engineering.

In aerospace engineering, structural lightweight remains one of the core design objectives. Here, a design methodology combining topology optimization (TO) with honeycomb materials is proposed to achieve lightweight for a typical aircraft double-lug joint structure (DLJS). The initial DLJS is topologically optimized using the variable density method to identify optimal material distribution. The optimized result is then reconstructed into a regular geometric model using the three dimensional (3D) modeling software SolidWorks 2022. In the reconstructed DLJS, the lower stress regions are replaced with honeycomb materials possessing superior mechanical properties or either removed to further enhance stiffness-to-weight ratio. Numerical strength verifications are performed on the final designed DLJS, demonstrating that the maximum stresses designed DLJS remain below the material yield strength under three typical load cases, meeting both strength requirements and safety margins. The mass of the designed DLJS is 38.44 kg, achieving a weight reduction rate of 59.7% compared to the initial DLJS (95.38 kg). Finally, the fabrication feasibility of the designed DLJS is evaluated, and a scaled-down DLJS specimen is fabricated using 3D printing technology with photopolymer resin. This work demonstrates the effectiveness and potential of TO combined with honeycomb materials in lightweighting complex 3D engineering components, providing valuable insights for the lightweight design of intricate 3D structures.