The stability and nonplanar buckling problem of current-carrying microwires in the
presence of longitudinal magnetic field are investigated by accounting for the
nonlinearities resulted from the axial elongation of the microwire’s centerline. Based
on the Euler–Bernoulli beam theory, modified couple stress theory, and Hamilton’s
principle, the nonlinear governing equations of the nonplanar motions of the
microwire are derived. By application of Galerkin’s approach, the nonplanar dynamic
responses are evaluated for both clamped-clamped and pinned-pinned boundary
conditions. The effects of dimensionless material length scale parameter, compressive
load, magnetic field force, and slenderness ratio on the nonplanar buckling instability
and the postbuckling configuration are discussed in detail. The obtained results
show that the nonplanar buckling instability of microwires occurs when the
magnetic field force becomes sufficiently large and the postbuckling configuration
depends on the magnitude of magnetic field force, slenderness ratio, and initial
conditions. The material length scale parameter can stabilize the microwire.
Moreover, the stability boundaries for the magnetic field parameter and
compressive load are analyzed, showing that an expected critical value of
magnetic field parameter may be achieved by choosing a suitable compressive
load as a trigger of automatic devices. Interestingly, it is found that the
presence of an axial compressive load has no effect on the postbuckling shape,
although it can destabilize the microwire system and amplify the postbuckling
amplitude.
Keywords
nonplanar postbuckling configuration, microwire carrying
electric current, modified couple stress theory,
longitudinal magnetic field, buckling instability