Characterization of quasi-static and dynamic failure in AA7075-based hybrid aluminum composites

This study aims to explore and understand the tensile strength and fatigue performance of AA7075 aluminum alloy by reinforcing it with cenospheres and molybdenum disulfide (MoS ₂ ), targeting applications that demand high strength and low weight, such as those in the aerospace and automotive sectors. Hybrid composites were fabricated using the stir casting method to ensure uniform distribution of reinforcements and minimal porosity. Four composite variations were developed with different weight fractions of cenospheres (2% and 4%) and MoS ₂ (2% and 4%). The tensile behavior was evaluated through quasi-static testing using ASTM-standard tensile tests, while dynamic performance under cyclic loading was assessed both experimentally and theoretically using Basquin’s equation. Fractographic analysis was conducted to investigate failure mechanisms under both loading regimes. Results showed that cenospheres significantly reduced the composite weight, while both reinforcements contributed to improvements in tensile strength and fatigue resistance. Fractography indicated that the reinforcements delayed crack initiation and propagation, thereby extending fatigue life. This work provides new insights into the synergistic effects of cenosphere and MoS ₂ reinforcements in AA7075 composites, offering a practical approach to developing advanced, lightweight materials with superior performance under both quasi-static and dynamic loading conditions.