Asymptotic homogenization-based strain gradient elastodynamics: Governing equations, well-posedness and numerical examples

We develop a strain gradient elastodynamics model for heterogeneous materials based on the two-scale asymptotic homogenization theory. Utilizing only the first-order cell functions, the present model is more concise and more computationally efficient than previous works with high-order truncations. Furthermore, we rigorously prove that the coefficient tensors, including the homogenized elasticity tensor, the strain gradient stiffness tensor, and the micro-inertial tensor are symmetric positive definite, thereby establishing the well-posedness of the strain gradient elastodynamics model, i.e., the existence and uniqueness of solutions. Numerical simulations are performed to confirm the theoretical findings and illustrate the characteristics of the present model in comparison with classical elastodynamics model (without strain gradient terms) and strain gradient models with higher-order truncations. The results indicate that the strain gradient model derived based on the first-order truncation can achieve an optimal balance between accuracy and computational cost.