Mechanical behavior of Cu–Ni functionally graded material-faced sandwich structures: A molecular dynamics study

To investigate the atomistic mechanical behavior of Cu–Ni functionally graded sandwich structures, molecular dynamics simulations were performed on models with Cu–Ni graded face sheets and a homogeneous Ni core. Tensile and compressive responses were examined at 220, 300, and 420 K for three thickness ratios (1:1:1, 1:2:1, and 1:4:1) and gradient indices from 0.1 to ∞. Mechanical behavior and deformation mechanisms were characterized using stress–strain curves, elastic modulus, common neighbor analysis, and a dislocation extraction algorithm. Results show that the mechanical properties are strongly governed by Ni content. Lower gradient indices and larger Ni-core fractions significantly increase yield strength and elastic modulus, but reduce yield strain and ductility. Increasing temperature decreases elastic modulus and promotes dislocation rearrangement and defect recovery. These results demonstrate that the strength, stiffness, and thermal adaptability of Cu–Ni functionally graded sandwich structures can be effectively tuned by controlling temperature, thickness ratio, and gradient index.