Analysis of wave propagation in micro/nanobeam-like structures: A size-dependent model

By incorporating the strain gradient elasticity into the classical Bernoulli-Euler beam and Timoshenko beam models, the size-dependent characteristics of wave propagation in micro/nanobeams is studied. The formulations of dispersion relation are explicitly derived for both strain gradient beam models, and presented for different material length scale parameters (MLSPs). For both phenomenological sizedependent beam models, the angular frequency, phase velocity and group velocity increase with increasing wave number. However, the velocity ratios approach different values for different beam models, indicating an interesting behavior of the asymptotic velocity ratio. The present theory is also compared with the nonlocal continuum beam models.