  The Eshelbian (or configurational) force is the main concept of a celebrated
theoretical framework associated with the motion of dislocations and, more in
general, defects in solids. In a similar vein, in an elastic structure where a
(smooth and bilateral) constraint can move and release energy, a force driving
the configuration is generated, which therefore is called by analogy
'Eshelby-like' or 'configurational'. This force (generated by a specific
movable constraint) is derived both via variational calculus and,
independently, through an asymptotic approach. Its action on the elastic
structure is counterintuitive, but is fully substantiated and experimentally
measured on a model structure that we have designed, realized and tested. These
findings open a totally new perspective in the mechanics of deformable
mechanisms, with possible broad applications, even at the nanoscale.
