Inferring unstable equilibrium configurations from experimental data

13th International Conference on Motion and Vibration Control; 12th International Conference on Recent Advances in Structural Dynamics

Virgin, L.N.^1 ; Wiebe, R.^2 ; Spottswood, S.M.^3 ; Beberniss, T.^3

School of Engineering, Duke University, Durham

NC

27708-0300, United States^1

Dept. Civil Engineering, University of Washington, Seattle

WA

98195, United States^2

Structural Sciences Center, AFRL, Wright-Patterson AFB

OH

45433, United States^3

关键词: Aerospace structure;    D. digital image correlation (DIC);    Equilibrium configuration;    Initial equilibriums;    Stable equilibrium;    Structural behaviors;    Structural component;    Unstable equilibriums;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/744/1/012090/pdf
DOI  :  10.1088/1742-6596/744/1/012090

来源: IOP

【 摘 要 】

This research considers the structural behavior of slender, mechanically buckled beams and panels of the type commonly found in aerospace structures. The specimens were deflected and then clamped in a rigid frame in order to exhibit snap-through. That is, the initial equilibrium and the buckled (snapped-through) equilibrium configurations both co-existed for the given clamped conditions. In order to transit between these two stable equilibrium configurations (for example, under the action of an externally applied load), it is necessary for the structural component to pass through an intermediate unstable equilibrium configuration. A sequence of sudden impacts was imparted to the system, of various strengths and at various locations. The goal of this impact force was to induce relatively intermediate-sized transients that effectively slowed-down in the vicinity of the unstable equilibrium configuration. Thus, monitoring the velocity of the motion, and specifically its slowing down, should give an indication of the presence of an equilibrium configuration, even though it is unstable and not amenable to direct experimental observation. A digital image correlation (DIC) system was used in conjunction with an instrumented impact hammer to track trajectories and statistical methods used to infer the presence of unstable equilibria in both a beam and a panel.