ABSOLUTE AND RELATIVE SIZE EFFECTS WITHIN NONLOCAL STRAIN GRADIENT ELASTIC BEAM MODELS, PART II

The present paper explores the size effects arising in a beam in bending by applying a theory of coherent nonlocal strain gradient (NSG) beam models, i.e., one admitting equivalent integral and differential approaches. Considering shear undeformable Euler–Bernoulli (EB) beams in bending it has been shown that the coherence requisite requires that the constitutive equations incorporate a pair of two-phase local/nonlocal models of which one is driven by strain, and the other by strain gradient. In the present paper a few benchmark beam models in static bending are considered for numerical applications which turn out to be exempt from paradoxical outcomes. Two distinct ways are proposed to evaluate size effects, namely: absolute size effects (with reference to the classic model) and relative size effects (with respect to the equiscale model featured by equal nonlocal and gradient length scale parameters). Absolute and relative size effects coincide only if the equiscale beam behaves as the classical beam (what is generally not true).