Thermo-Mechanical Behavior and Strain Hardening Characteristics of Functionally Graded Carbon/Glass Fiber Hybrid Composite Leaf Spring Plate

Abstract

Functionally graded hybrid composite laminates offer significant potential for lightweight structural applications requiring high stiffness, durability, and damage tolerance. In this study, a carbon/glass fiber mat-reinforced epoxy laminate with a thickness-wise functional gradation was fabricated using the hand lay-up technique and evaluated for composite leaf spring applications. Carbon fiber mats were positioned at the outer and central layers to enhance load-bearing capability, while glass fiber mats were incorporated in intermediate layers to improve energy absorption and crack resistance. Tensile analysis revealed stable post-yield deformation with a high strength coefficient (K = 4559.3 MPa) and strain-hardening exponent (n = 0.4236) based on the Hollomon model. Dynamic mechanical analysis demonstrated high storage modulus and improved damping characteristics with a glass transition temperature of approximately 65–70°C. Flexural and impact evaluations confirmed nonlinear load-bearing behavior and enhanced crack propagation resistance. The developed laminate exhibited promising thermo-mechanical performance for advanced lightweight leaf spring systems.