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).