Abstract
Design of stiffened panels requires evaluating their stability under various loading combinations for all possible scenarios regarding material degradation or initial geometric imperfections that could affect them. Both static and dynamic loading conditions are to be investigated for assessing the buckling strength. In this work, dynamic buckling under in-plane uniform axial compression loading having the form of a transient pulse with finite duration is evaluated through nonlinear finite element modelling. A welding induced defect that consists of an initial geometric imperfection modifying the skin plate curvature in the longitudinal direction was incorporated. The Budiansky buckling criterion was employed to predict instability under this dynamic loading. The obtained results have shown that the pulse period yields a drastic effect on the buckling strength. For the considered boundary conditions, half-sine like pulses having periods that are comparable to two times the period of the first mode of natural vibrations of the stiffened plate were found to reduce hugely the buckling strength, with the dynamic buckling load representing almost only half its static value.
Highlights
Stability of stiffened panels is a main concern in many engineering applications such as aircrafts and ships [1,2]
Stiffened panels are subjected to various loading conditions which can be either of static or dynamic character and are subjected to various alterations that can take the form of material degradation or geometric imperfections
In the presence of certain values of relatively large initial geometric imperfections and for pulse durations of the applied load that are close to the first period of natural flexural vibrations of either the beam or the plate, the dynamic load factor (DLF) was found to be smaller than unity resulting in the fact that dynamic buckling can be more severe than static buckling
Summary
Stability of stiffened panels is a main concern in many engineering applications such as aircrafts and ships [1,2]. In the presence of certain values of relatively large initial geometric imperfections and for pulse durations of the applied load that are close to the first period of natural flexural vibrations of either the beam or the plate, the DLF was found to be smaller than unity resulting in the fact that dynamic buckling can be more severe than static buckling This observation has been found to be valid for axially impacted composite plates [11]. MATEC Web of Conferences laminated composite plates have shown that a DLF smaller than unity can be obtained for a given composite plate which is axially impacted with a compressive load of period close to the first period of natural lateral vibration of the plate From this brief literature review, one can see that buckling due to dynamical loading acting on structures cannot be always estimated by performing static analysis of the problem. These periods were chosen to be close to the characteristic time of the structure defined as the inverse of the first modal frequency of natural vibrations
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