Lightweight composite optimization of URAL-4320 chassis using CFRP and BFRP: Structural and modal finite element analysis

• Finite element–based lightweight optimization of URAL-4320 truck chassis using CFRP and BFRP composites. • Inclusion of anisotropic composite layup modeling and validated mesh convergence study. • Comparative structural and modal analysis demonstrating material performance differences. • CFRP achieved higher stiffness and natural frequencies; BFRP offered superior damping and impact energy absorption. • Results provide design insights for lightweight, durable military and heavy-duty vehicle chassis systems. The chassis frame is a vehicle’s primary structural backbone and its material selection critically affects mass, dynamic performance and durability. This work evaluates lightweighting strategies for the URAL-4320 ladder-frame chassis by replacing HSLA steel with advanced composites — Carbon Fiber Reinforced Polymer (CFRP) and Basalt Fiber Reinforced Polymer (BFRP) — and performing structural and modal finite element analyses in ANSYS R19.2 on CAD models created in SolidWorks 2020. Static analyses compared von Mises stress, shear stress, strain energy and total deformation across load cases representative of payload and drivetrain loads. Modal and harmonic analyses identified natural frequencies, mode shapes and the chassis’ dynamic response. A mesh convergence study and an orthotropic composite layup modelling procedure are documented to ensure numerical robustness and realistic anisotropic behaviour. Results indicate that CFRP provides markedly higher stiffness, lower deformations and higher natural frequencies, favoring precision and vibration resistance; BFRP yields higher strain energy and modal deformation, indicating improved impact energy absorption and damping potential but lower stiffness. We discuss tradeoffs in cost, manufacturability, and survivability, and provide design recommendations for application-specific selection between CFRP and BFRP.