Electromechanical buckling and postbuckling of micro thin film bonded to a compliant substrate


סמינר תואר שני – הנדסת מכונות

Electromechanical buckling and postbuckling of micro thin film bonded to a compliant substrate

Hesham Badir ,השאם בדר – סטודנט תואר שני
MSc Student – Mechanical Engineering Department

הסמינר מתקיים דרך הזום בקישור זה

Meeting ID: 975 5047 1819
Password: 021259

This work investigates the electromechanical buckling and post-buckling response of a micro thin film that is
bonded to a compliant substrate. The system consists of thin elastic electrode that is bonded to a compliant
substrate. The bottom of the compliant substrate is bonded to an electrically grounded rigid electrode. Mechanical
buckling of the film occurs when the applied compression stresses approach the critical compression buckling
stresses. However, as will be shown, buckling may occur even when the applied compression stresses are lower
the critical value. Such instigated buckling take place if the film-substrate system is applied to a voltage
difference between the elastic and rigid electrodes. This work shows that buckling of the film can be instigated by
applying electrostatic attraction forces on the film which couples electromechanical instability with the classical
buckling instability. The governing nonlinear Von-Karman equilibrium equations of the critical
electromechanical buckling and post-buckling of the elastic thin film are solved.
The electromechanical buckling modes are periodic patterns and are characterized by the upper-bound elastic
strain energy method. Each of the postulated buckling patterns is characterized by the extent of strain-energy
reduction relative to its unbuckled perfect flat state. Based on experimental results in the literature, the postulated
periodic buckling patterns are One-dimensional, square checkerboard, hexagonal, and herringbone pattern. The
preferred pattern is identified as the pattern that is characterized with maximum elastic strain energy reduction
relative to the unbuckled state.
The analytical solutions of the buckling and postbuckling states is validated by the numerical solution of each
pattern mode. It has been shown that increasing the voltage leads to a second instability at which the one pattern
becomes unstable and it bifurcates to another one.
Accurate control of the electromechanical buckling phenomena of an elastic thin film electrode can be
implemented in different MEMS and NEMS devices, such as On/Off switching of micro mirrors.

Keywords: Von-Karman equations, Electromechanical buckling, Buckling of thin film/plate

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