The novelty of this study is presentation of an exact solution for prediction of postbuckling behavior of shear deformable micro- and nano-scale beams based on modified couple stress theory and using principle of minimum potential energy. Timoshenko and Reddy-Levinson beam theories are applied to consider the shear deformation effect and Von Karman nonlinear kinematics is used to describe the n...

We present a study on swelling-induced circumferential buckling of tubular shaped gels. Inhomogeneous stress develops as the gel swells under mechanical constraints, which gives rise to spontaneous buckling instability without an external force. Full control over the postbuckling pattern is experimentally demonstrated. A simple analytical model is developed using elastic energy to predict stabi...

We uncover how nonlinearities dramatically alter the buckling of elastic beams. First, we show experimentally that sufficiently wide ordinary elastic beams and specifically designed metabeams-beams made from a mechanical metamaterial-exhibit discontinuous buckling, an unstable form of buckling where the postbuckling stiffness is negative. Then we use simulations to uncover the crucial role of n...

Local buckling and postbuckling of panels stiffened by stringers and rings and subjected to combined in-plane loads is explored with the use of a single module model that consists of one stringer and a width of panel skin equal to the stringer spacing. The cross-section of the skin-stringer module is discretized and the displacement field is assumed to vary trigonometrically in the axial direct...

The optimization of aerospace structures is a very complex problem, owing to the hundreds of design variables a multidisciplinary optimization may contain, so that multilevel optimization is required. This paper presents recent developments to the optimization software VICONOPT MLO, a multilevel optimization interface between the analysis and design software packages VICONOPT and MSC/NASTRAN. T...

Abstract-Results for the initial postbuckling behavior of laminated beams are presented. Shear deformation effects are incorporated by relaxing certain assumptions of thin beam/plate theory. The analysis used is in the spirit of Koiter [Doctoral thesis, Delft, Amsterdam, English translation AFFDL-TR-70-25, (1970)], who developed asymptotic expressions for the potential energy in the neighborhoo...

The postcritical analysis performed for a structure optimized only for buckling constraints shows that the behaviour of the designed element after buckling is in many cases unstable. That should be considered as a drawback of the standard design because the applicability of such an unstable optimal structure may be questionable. Recently, the new concept of structural optimization against insta...

This work explores the postbuckling behavior of a marine stiffened composite plate in presence initial imperfections. The imperfection shapes are derived from buckling mode and their combinations. Thereafter, these applied to model, nonlinear large deflection finite element progressive failure analyses performed ANSYS 18.2 software. Hashin criterion is employed model plate. effect geometric on ...

Lithographically defined electrical interconnects with thin, filamentary serpentine layouts have been widely explored for use in stretchable electronics supported by elastomeric substrates. We present a systematic and thorough study of buckling physics in such stretchable serpentine microstructures, and a strategic design of serpentine layout for ultra-stretchable electrode, via analytical mode...