The effect of surface stress on the stiffness of cantilever beams remains anoutstanding problem in the physical sciences. While numerous experimentalstudies report significant stiffness change due to surface stress, theoreticalpredictions are unable to rigorously and quantitatively reconcile theseobservations. In this Letter, we present the first controlled measurements ofstress-induced change in cantilever stiffness with commensurate theoreticalquantification. Simultaneous measurements are also performed on equivalentclamped-clamped beams. All experimental results are quantitatively andaccurately predicted using elasticity theory. We also present conclusiveexperimental evidence for invalidity of the longstanding and unphysical axialforce model, which has been widely applied to interpret measurements usingcantilever beams. Our findings will be of value in the development of micro-and nanoscale resonant mechanical sensors.
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