Experimentally probing the stability of thin-shell structures under pure bending

Abstract

This paper studies the stability of space structures consisting of longitudinal, open-section thin-shells transversely connected by thin rods subjected to a pure bending moment. Localization of deformation, which plays a paramount role in the nonlinear post-buckling regime of these structures and is extremely sensitive to imperfections, is investigated through probing experiments. As the structures are bent, a probe locally displaces the edge of the thin shells, creating local dimple imperfections. The range of moments for which the early buckling of the structures can be triggered by this perturbation is determined, as well as the energy barrier separating the pre-buckling and post-buckling states. The stability of the local buckling mode is then illustrated by a stability landscape, and probing is extended to the entire structure to reveal alternate buckling modes disconnected from the structure’s fundamental path. These results can be used to formulate efficient buckling criteria and pave the way to operating these structures close to their buckling limits, and even in their post-buckling regime, therefore significantly reducing their mass. This article is part of the theme issue ‘Probing and dynamics of shock sensitive shells’.

Foreword to the special issue on new developments in structural stability

“…The authors and their co-workers have applied dimensional reduction to other nonlinear systems with great success, and the contribution in this paper should prove useful in modelling systems comprising the shell strip beams such as those employed as the structural elements in the space frames designed for the solar arrays of Royer et al . [ 6 ].…”

“…Discovering structural response by probing can be an effective technique whether it is conducted experimentally or computationally, as will be evident in the first six papers. The paper by Royer et al [6] on the ultra-lightweight structures used for supporting solar cell arrays in space employs both experimental and computational probing to reveal the highly complex buckling behaviour of these structures. The following quote from the abstract of this paper succinctly encapsulates the objectives of the technique: 'These results can be used to formulate efficient buckling criteria and pave the way to operating these structures close to their buckling limits, and even in their post-buckling regime, therefore significantly reducing their mass.…”

“…The authors make use of dimensional reduction methods to reduce the nonlinear partial differential equation governing the buckling to a much simpler ordinary differential equation that accurately captures the localization and the progressive loss in bending stiffness. The authors and their co-workers have applied dimensional reduction to other nonlinear systems with great success, and the contribution in this paper should prove useful in modelling systems comprising the shell strip beams such as those employed as the structural elements in the space frames designed for the solar arrays of Royer et al [6].…”