Increasing the Bucking Capacity with Modal Geometric “Imperfections”

Abstract A recent design paradigm, named modal nudging, exploit geometric “imperfections” with negligible self‐weight change to nudge the baseline structure onto equilibrium paths of greater load‐carrying capacity. Indeed, not all imperfections are detrimental in buckling problems. This paper presents a simple automatic procedure for designing a geometric change based on a Koiter‐inspired reduced‐order model (ROM). The ROM allows a quick estimate of the equilibrium paths of a structure with geometric imperfections spanned by the first closely‐spaced linearized buckling modes. It makes it possible a fast random search in the reduced space for selecting a geometric alteration that nudges the structure onto a beneficial attractive path. Nevertheless, it is worth noting that even nudging the structure onto a stable path is not a sufficient condition for imperfection insensitivity. This paper demonstrates the importance of tailoring the amplitude and shape of the design alteration such that additional accidental imperfections do not nudge back the structure onto detrimental attractive paths. This goal is accomplished by exploiting the same ROM also to assess the sensitivity of the current altered geometry during the design stage.