Dynamic Buckling of the Strut

Aneta Brzuzy

ABSTRACT

Objective - This paper elaborates on the loss of stability, which occurs in the steel strut, characterized by the simple support scheme, under the impact-type load. The unstable behaviour of the strut is initiated by a dynamic, lateral load q(x,t) continuously distributed along the strut length The research is based on the theory of the moderately large deflection in case of small plastic elastic deformations. The description includes the longitudinal wave reaction of the strut. The state of the buckling is defined as the continual growth of the internal energy dissipation.

Methodology/Technique - The result has been obtained by the finite difference method, based on the discreet model of the strut. Additionally, the explicit scheme of the integral equation method of the dynamic balance in relation to time has been used. The research took into account the bounce of the longitudinal wave from the supports of the strut. The reaction consisting in plastic deformation of the strut, has been described of the strut cross-section.

Findings - The applied method estimated the dynamic value of the critical force and its relation to the static force. The analyses proved that the buckling of the strut occurs in two phases: the initial stage, consisting in the minor lateral vibrations of the strut, deprived of the notable dissipation of energy and the phase of the uncontrolled dissipation, accompanying the increasing lateral deformations. Determining of the duration of the initial stadium may be crucial for the design of the strut in relation with the loads providing that the permanent deformation would occur.

Novelty - The paper took into account the longitudinal wave reaction of the strut under the lateral load – the influence of the propagation of the longitudinal waves and their interaction with the crosswise vibrations, generated by the dynamic loss of stability.

Type of Paper: Conceptual

Keywords: buckling; dynamic loading; elastic-plastic behaviour; dynamic stability of a strut; differential approximation; axial wave effects.

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