Leaf springs for commercial vehicles are prone to fatigue deformation and fracture under long-term overload operation. Excessive load drives the spring material to work close to its yield strength and aggravates alternating stress concentration. While structural and technological optimization cannot completely avoid overload failure, targeted upgrades in materials, structural design, assembly matching and manufacturing processes can significantly improve the overload resistance and service life of leaf springs.
Material upgrading is the fundamental optimization measure. Traditional ordinary spring steel is replaced with 1800–2000 MPa high-purity micro-alloy spring steel, which delivers higher yield strength and fatigue limit to resist plastic deformation under heavy loads. Strict control of surface decarburization is also implemented to eliminate surface defect-induced crack initiation under overload impact, improving the overall structural stability of the spring.
Structural optimization focuses on reducing stress concentration. The safety factor of critical load-bearing sections is raised from 1.25 to 1.35–1.50. A multi-segment variable-curvature parabolic profile is adopted to homogenize stress distribution and avoid local stress peaks. Rounded spring eye transitions and polished blade ends eliminate sharp notches and edge cracking risks. For extreme overload conditions, proper blade quantity increase and thinner single-blade design realize uniform load sharing and better impact resistance.
In terms of assembly design, reducing the U-bolt spacing effectively lowers the maximum bending moment of the spring. Wear-resistant gaskets installed between blades prevent dry friction and surface scratching during large deformation. Reinforced lifting lugs and high-load bushings are equipped to avoid additional impact load caused by accessory failure, stabilizing the overall force-bearing state of the suspension system.
Advanced manufacturing processes further enhance overload durability. Composite intensive shot peening produces stable surface residual compressive stress to inhibit fatigue crack expansion. Pre-compression treatment stabilizes spring deflection and eliminates internal latent defects. Optimized heat treatment achieves uniform microstructure to balance strength and toughness. Besides, CAE simulation and bench fatigue tests under 1.25–1.5 times rated load are carried out to fully verify the structural reliability of optimized leaf springs under actual overload working conditions.
Post time: Aug-13-2026
