The period solidified the practice of modeling plate vibrations through modal decomposition, integrating rotatory inertia and shear effects into two-dimensional plate theories and aligning them with three-dimensional elasticity. Rayleigh-type approaches provided compact frequency expressions for varied boundary conditions, accelerating design-oriented analyses and the generation of mode-based spectra. The methodological emphasis on combining subsystem modes with compatibility constraints foreshadowed later synthesis techniques and efficient computational strategies.