Dynamic Mechanical Properties and Constitutive Modeling of Metal Rubber with the Effect of Spring Coil Outer Diameter Under High-Speed Impact Loading

To explore the dynamic mechanical performance of metal rubber (MR) under high-speed impact loading, cylindrical solid MR specimens with spring coil outer diameters of 2–4 mm and relative densities of 0.2–0.35 have been prepared, and dynamic compression tests have been carried out utilizing the split Hopkinson pressure bar (SHPB) device at strain rates of 400–1000 s−1. The dynamic stress–strain response of MR has been systematically analyzed, and the influences of strain rate, spring coil outer diameter, and relative density on its dynamic elastic modulus and energy absorption properties have also been quantitatively investigated. The results reveal that the dynamic stress–strain relationship of MR under high-speed impact presents significant nonlinearity and distinct strain rate effect. MR specimens with higher relative density, smaller spring coil outer diameter, or higher strain rate exhibit a larger dynamic elastic modulus, while those with higher relative density, larger spring coil outer diameter, or lower strain rate achieve higher energy absorption efficiency. A modified dynamic constitutive model for MR based on the Sherwood-Frost model has been developed by incorporating strain rate, relative density, and spring coil outer diameter as key influencing variables. The results show that the maximum mean relative error between the predicted and experimental data is less than 20%, indicating a favorable accuracy and reliability of the constitutive model. The proposed model can effectively characterize and predict the dynamic mechanical behavior of MR under high-speed impact loading conditions, providing a reliable theoretical basis for the engineering application of MR in impact-resistant structures.