Acceleration insensitivity of thickness frequencies of doubly rotated quartz crystal disks

Initial fields of displacement gradients and strains caused by steady accelerations of arbitrary direction are calculated from finite-element solutions of R.D. Mindlin´s two-dimensional, first-order equations of equilibrium for crystal plates. The frequency equation for incremental thickness vibrations of circular crystal disks under initial stresses is obtained by the extension of a recently obtained solution for energy-trapped thickness vibrations and solved by a perturbation method. Acceleration sensitivity of SC- and AT-cuts of quartz disks are studied symmetrically